Mechanisms of Aneuploidy and Role of Polyploidy in Evolution

## **Chapter 2** Mechanisms of Aneuploidy

*Emine Ikbal Atli*

### **Abstract**

Aneuploidy is a very common occurrence in humans and occurs in an estimated 20–40% of all pregnancies. It is the most prominent cause of miscarriages and congenital defects in humans and is the main obstacle to infertility treatment. The vast majority of aneuploidies are caused by maternal meiotic non-disjunction errors. High levels of recombination errors were observed in studies on fetal oocytes. This suggests that some oocytes are more prone to not being separated due to events occurring before birth. Cell cycle checkpoints that work in the meiotic phase and metaphase-anaphase transition work more moderately in women than in men. As a result, while there are abnormal cells that have been sorted out in spermatogenesis, in females these cells can escape the actual control and ultimately give rise to aneuploid eggs.

**Keywords:** nondisjunction, abnormal segregation, chromosome

### **1. Introduction**

Although aneuploidy is a serious health problem, the reasons behind this phenomenon have not been fully confirmed. The development of a comprehensive set of tests is necessary for the evaluation and detection of aneugenic chemicals. The reliability of any aneuploidy analysis is always questioned by the fact that the mechanisms that cause aneuploidy are poorly understood, in part due to the multitude of factors involved in the occurrence of chromosome segregation and nondisjunction [1]. Errors in chromosome segregation during meiosis are usually seen in human oocytes and cause aneuploidy in embryos. These errors increase dramatically in the eggs of older women.

Here, we attempt to summarize recent studies commenting on how progressive disruption of chromosome structures contributes to age-related aneuploidy. In addition, various cellular pathways that cause aneuploidy in oocytes of women of all ages are being investigated. Data from mouse and human oocytes are discussed with emphasis on studies focusing on this phenomenon in humans [2].

#### **2. Meiosis in human oocytes**

Meiosis involves two sequential cell divisions in which homologous chromosomes (meiosis I) are separated in the first stage, followed by sister chromatids (meiosis II). In the first meiosis, the homologous chromosomes separate from each other, then the homologous chromosomes are joined together. These connections are established early in oocyte development during the growth of the female fetus in a process called homologous recombination. The maternal and paternal chromosomes are

first compressed by the synaptonemal complex and then crossed over. After crossover, new sister chromatids are formed, containing adjacent portions of maternal and paternal sister chromatids. Cohesin complexes that previously linked sister chromatids of each homologous chromosome now link homologous chromosomes together: Cohesin (distal cohesin) distal to the crossover sites connects homologs, while cohesin (proximal cohesin) between crossover sites and centromeres continues to bind sister chromatids [3]. The chromosome configuration that turns out to be two homologous chromosomes is called bivalent. As meiosis I occurs, the bivalents must be oriented on the spindle so that the two sister chromatids contained in each homologous chromosome face the same spindle pole. The kinetochores of sister chromatids must behave as a single kinetochore. It is thought that adding sister kinetochores to a functional location will facilitate this function. Oocytes then enter a state of cellular stagnation called 'interphase' in processes spanning different periods of time. The functional units of oocyte and somatic cells in the ovary are called follicles [4–6]. During storage, the oocytes remain small and are surrounded by a single layer of squamous cell epithelium called the "primordial follicle". Periodically, some primordial follicles begin to grow. Somatic cells supply the oocyte with macromolecular precursors through gap junctions, and oocyte volume increases significantly. This enrichment of nutrients prepares the oocyte [7, 8] to mature into an egg, which after fertilization can give rise to an embryo.

Oocytes emerge from dictyate arrest after puberty. In the middle of the menstrual cycle, the rise of luteinizing hormone from the pituitary gland causes the oocyte to continue meiosis and mature into a fertilizable egg. First, the nucleus disintegrates and sets of meiotic spindles are formed, which align the chromosomes in meiosis I metaphase. The spindle progresses to the oocyte cortex, where homologous chromosomes separate. One set of homologous chromosomes remains in the oocyte, while the other is extruded into the first polar body formed. Molecularly, the segregation of chromosomes during meiosis I is activated by the cleavage of Rec8, a meiosis-specific subunit of the cohesin complex [9]. Rec8 is cleaved by Separase, which is activated along with anaphase. During anaphase I, only the cohesin in the arm region is broken down so that the chromosomes can separate from each other. Cohesin in the centromeric regions is protected from cleavage by Shugoshin proteins (Sgo), so that sister chromatids stay together during anaphase I. As meiosis II occurs, the second meiotic spindle fuses [10–13]. The maturing egg has transitioned to the quiescent phase in metaphase II and is transported to the fallopian tube during ovulation. The egg waits to complete its second meiosis until it is fertilized by the sperm. As the second meiosis continues, the Sgo proteins migrate to the kinetochores, and in anaphase II, the cleavage of the centromeric cohesin takes place [14–17]. In order to complete meiosis, the sister chromatids of the remaining chromosomes, the oocyte and the second polar body, must be formed. Chromosomes from the oocyte and sperm separate as the pronuclear envelope and then stand ready for the first mitotic division of the embryo. The embryo then divides into a multicellular blastocyst and implants in the uterus to develop further [18–20].

#### **3. Types of aneuploidy in oocytes**

Recent technological advances have increased the chances of catching aneuploidy in eggs or in the early stages of embryonic development. In pre-implantation genetic diagnosis, an embryo may sometimes be biopsied and analyzed for genetic abnormalities to select healthy embryos for implantation. As an alternative to this technique, testing oocytes can minimize the need to test embryos. In particular, polar bodies can be used to determine the cytology of an oocyte without damaging

#### *Mechanisms of Aneuploidy DOI: http://dx.doi.org/10.5772/intechopen.101586*

it [21, 22]. The use of polar bodies for aneuploidy detection in IVF applications also facilitates embryo selection before implantation [23, 24]. Genetic analysis of both polar bodies can accurately detect aneuploidy in mature oocyte because all chromosomal copies are extruded into polar bodies [25–27]. For example, an excess chromosome in the first polar body indicates loss of the homolog of that chromosome in the oocyte after meiosis I, while an incorrect chromosome number in the second polar body indicates a chromosome segregation error in meiosis II. On the other hand, the second polar body is formed only after fertilization. Chromosomes from biopsied polar bodies are best previously analyzed by fluorescent in situ hybridization (FISH). Although widely used for embryo selection, clinical applications of FISH are only informative for a particular chromosome and results may be inaccurate [28]. New, more sensitive methods such as Sequence Comparative Genome Hybridization (aCGH) and next-generation sequencing (NGS) platforms provide improved statistics for aneuploidy prevalence and better characterization of segregation errors [29].

Two classical ways that have been suggested to account for chromosome segregation errors in meiosis are nondisjunction (NDJ) and premature separation of sister chromatids (PSSC). For NDJ, homologous chromosomes or sister chromatids cannot separate at meiosis I or meiosis II, respectively. Similar segregation errors are seen between meiosis I and II, although meiosis II error rates have sometimes been reported to be higher.

This can be explained by the fact that errors that can be seen in meiosis I occur in meiosis II, because early cleavage sister chromatids can separate correctly in meiosis I, while errors are observed later in meiosis II.

Surprisingly, PSSC mutations in meiosis I could be corrected by a 'balance' error during meiosis II: if both the first and second polar bodies share mutual errors (for example, a loss in the polar body first followed by a second gain in the polar body; or vice versa) the resulting oocyte will have the correct number of chromosomes [30, 31].

Chromosome pairs 15, 16, 21, and 22 are the chromosomes that most commonly contribute to human aneuploidies, but data on the contributions of other chromosomes are lacking due to limited statistical information for types of aneuploidy. Frequently, an oocyte will experience simultaneous errors involving more than one chromosome, suggesting that some oocytes are susceptible to global dysfunction. This effect is also evident in embryos where up to 42% of detected aneuploidies contain more than one chromosome [32, 33].

However, the etiology of embryonic aneuploidy is more complex, as errors can also occur from sperm or during rapid mitotic divisions in embryogenesis [34, 35]. Advances in single-cell whole genome amplification (WGA) allow unprecedented characterization of genomic content within polar bodies.

Analyzes of the genomes of polar body-oocyte and polar body-embryo triplets (i.e. a biopsy of an oocyte or embryo fused with first and second polar bodies) revealed an alternative mechanism of segregation, termed 'reverse segregation' [36].

Reverse segregation occurs when sister chromatids separate at meiosis I so that there are no homologous chromosomes.

Reverse segregation results in the correct number of chromosome cells. The chromatid pairs, the copies inherited by the oocyte and first pole body, have different parental origins and are heterozygous at the centromeres.

After meiosis I, their connection is broken and during metaphase II, alignment problems may occur in the spindle fibers. In one study; although it was the most observed error in number, reverse segregation was detected in less than 10% of the triples analyzed [36]. Interestingly, all of the donors participating in this study produced at least one oocyte or embryo that underwent reverse segregation. The oocytes included in this study were obtained from women aged 33–41 years. A similar study examining oocytes from younger donors aged 25–35 years reported that no reverse segregation was observed [26, 36].

#### **4. Causes of aneuploidy increasing with age**

Women experience a gradual decrease in their ability to get pregnant as they age. Loss of reproductive ability usually occurs approximately 10 years after the age of 35. Meiotic chromosome segregation errors increase very clearly in women of this age group. A large-scale cytogenetic analysis examining more than 20,000 human oocytes by FISH reported that aneuploidy occurred in 20% of oocytes retrieved from women aged 35 years, increasing to approximately 60% in women over 43 years of age [37].

Current studies with aCGH have confirmed that the rates of aneuploidy increase dramatically in oocytes from older women [23, 27, 38–40]. Conservation of bivalents is crucial for correct chromosome segregation. However, recent studies in human oocytes reveal that the structure of bivalents is prone to fragmentation in oocytes of older women.

In mice and humans, two major structural defects occur with increasing age in bivalents. First, sister kinetochores disperse over long distances, which is incompatible and often associated with incorrect attachment to the meiotic spindle. Second, the bivalents formed in senescent oocytes are more often separated into individual chromosomes, called univalents. Univalent pairs may split uncoordinatedly and may also contribute to aneuploidy. Interestingly, it is possible for both defects to result in an inverse decomposition pattern, as we will discuss below [41–44].

Sister chromatids in mouse and human oocytes lose compatibility with age, which can cause misalignment of bivalents in meiosis I.

Loosely related sister chromatids may no longer function properly as they align on the meiotic spindle. In human oocytes, separated sister kinetochores tend to form more merotelic attachment to spindle microtubules.

In addition, other age-related factors may promote defective kinetochoremicrotubule attachments.

Excessive segregation of sister kinetochores in human oocytes causes bivalents to take on unexpected alignments in the meiotic spindle. In a newly defined bivalent configuration called 'inverted bivalents', the bivalents are rotated to the spindle axis: the sister chromatids of a homologous chromosome misalign and misalign, linking microtubules at opposite spindle poles instead of orienting them to the same spindle pole, as in mitosis [45–48].

Both half and fully inverted bivalents occur. Only one pair of sister chromatids is attached to opposite spindle poles in semi-inverted bivalents, while both pairs are attached to opposite poles in fully inverted bivalents. Reverse bivalents have been observed more frequently in oocytes from older females and are associated with increasing distances between sister kinetochores. Since sister chromatids are oriented separately on the spindle, similar to mitosis, fully inverted bivalents can lead to an inverse pattern of segregation. Bivalents also sometimes appear bent along their axis because homologous chromosomes rotate relative to each other, which can put more pressure on the already weakened cohesion.

The age-related loss of balance applicable to bivalents is not limited to the pericentromeric regions surrounding the kinetochores. There is also danger in the harmony that connects homologous chromosomes. Homologous chromosome pairs in bivalents often remain separated by large gaps in oocytes of aged mouse and human females. These and similar structural defects are indicative of decreased

#### *Mechanisms of Aneuploidy DOI: http://dx.doi.org/10.5772/intechopen.101586*

compatibility between bivalent homologous chromosomes. In more complex cases, bivalents sometimes divide earlier into two separate chromosomes (univalents) before anaphase I. The prevalence of univalents increases exponentially with age, occurring in 40% of oocytes in women older than 35 years and 10% of oocytes in women aged 30–35 years. In mouse oocytes, univalent alignment problems can cause chromosome separation errors. Univalents in mouse and human oocytes could also align on the first meiotic spindle, similar to mitotic chromosomes, with both sister kinetochores facing opposite spindle poles. This can create a mitosis-like pattern of segregation and result in reverse segregation: equal segregation of both univalents into sister chromatids will result in the correct chromosome number acquired by the oocyte and the first polar body, but the chromatids will originate from different parental origins. However, the sister chromatids have been divided much earlier and could not be properly aligned to the spindle at metaphase II.

The molecular mechanisms that may cause these dramatic developments in chromosomal organization in human oocytes, which change with advancing age, are still unresolved. However, studies in mice have clarified the loss of cohesin as a major contributor to age-related aneuploidy. Cohesin complexes containing Rec8 in mouse oocytes are already present during DNA replication in the early stages of meiosis. After fertilization, they are thought to be renewed when DNA is replicated again in the embryo. Therefore, the cohesin complexes must remain in place during the prolonged period of dictation arrest to ensure correct chromosome segregation in meiosis. Rec8 levels are severely reduced in bivalents of oocytes from naturally aged mice [48–51].

#### **5. Conclusions**

Fertility declines gradually as women age, and by midlife women begin to lose their ability to produce healthy eggs. Meiotic chromosomes experience increased age-related structural changes that can result in increased Error rates in chromosome segregation. Newly described processes have been identified in human oocyte structures that may explain the emergence of an alternative form of segregation. Conducted studies will better reveal why oocytes are often defective, leading to age-related infertility. Recent studies have reported that meiosis in mammalian females is inherently error-prone, leading to high aneuploidy and sterility. The cellular pathways responsible for chromosome separations are prone to error and affect females of all ages.

#### **Acknowledgements**

I would like to thank my supervisors Hakan Gurkan for all his help and advice.

#### **Conflict of interest**

The authors declare no conflict of interest.

#### **Acronyms and abbreviations**

IVF in-vitro fertilization FISH fluorescent in situ hybridization


### **Author details**

Emine Ikbal Atli Trakya University Faculty of Medicine, Department of Medical Genetics, Turkey Balkan Campus, Edirne, Turkey

\*Address all correspondence to: emine.ikbal@gmail.com; eikbalatli@trakya.edu.tr

© 2021 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

*Mechanisms of Aneuploidy DOI: http://dx.doi.org/10.5772/intechopen.101586*

#### **References**

[1] Seoane AI, Güerci AM, Dulout FN. Mechanisms involved in the induction of aneuploidy: The significance of chromosome loss. Genetics and Molecular Biology. 2000, 2000;**23**(4): 1077-1082

[2] Webster A, Schuh M. Mechanisms of Aneuploidy in Human Eggs. Trends Cell Biol. 2017;**27**(1):55-68

[3] Sakuno T, Watanabe Y. Studies of meiosis disclose distinct roles of cohesion in the core centromere and pericentromeric regions. Chromosome Research. 2009;**17**:239-249

[4] Toth A et al. Functional genomics identifies monopolin: A kinetochore protein required for segregation of homologs during meiosis i. Cell. 2000;**103**:1155-1168

[5] Rabitsch KP et al. Kinetochore recruitment of two nucleolar proteins is required for homolog segregation in meiosis I. Developmental Cell. 2003;**4**: 535-548

[6] Yokobayashi S, Watanabe Y. The kinetochore protein Moa1 enables cohesion-mediated monopolar attachment at meiosis I. Cell. 2005;**123**: 803-817

[7] Peters H. The development of the mouse ovary from birth to maturity. Acta Endocrinologica. 1969;**62**:98-116

[8] Herlands RL, Schultz RM. Regulation of Mouse oocyte growth: probable nutritional role for intercellular communication between follicle cells and oocytes in oocyte growth. The Journal of Experimental Zoology. 1984;**229**:317-325

[9] Watanabe Y, Nurse P. Cohesin Rec8 is required for reductional chromosome segregation at meiosis. Nature. 1999; **400**:461-464

[10] Buonomo SB et al. Disjunction of homologous chromosomes in meiosis I depends on proteolytic cleavage of the meiotic cohesin Rec8 by separin. Cell. 2000;**103**:387-398

[11] Llano E et al. Shugoshin-2 is essential for the completion of meiosis but not for mitotic cell division in mice. Genes & Development. 2008;**22**: 2400-2413

[12] Lee J et al. Unified mode of centromeric protection by shugoshin in mammalian oocytes and somatic cells. Nature Cell Biology. 2008;**10**:42-52

[13] Gomez R et al. Mammalian SGO2 appears at the inner centromere domain and redistributes depending on tension across centromeres during meiosis II and mitosis. EMBO Reports. 2007;**8**: 173-180

[14] Lee J et al. Unified mode of centromeric protection by shugoshin in mammalian oocytes and somatic cells. Nature Cell Biology. 2008;**10**:42-52

[15] Gomez R et al. Mammalian SGO2 appears at the inner centromere domain and redistributes depending on tension across centromeres during meiosis II and mitosis. EMBO Reports. 2007;**8**:173-180

[16] Clift D, Schuh M. Restarting life: Fertilization and the transition from meiosis to mitosis. Nature Reviews. Molecular Cell Biology. 2013;**14**: 549-562

[17] Chambon JP et al. The PP2A inhibitor I2PP2A is essential for sister chromatid segregation in oocyte meiosis II. Current Biology. 2013;**23**:485-490

[18] Clift D, Schuh M. Restarting life: fertilization and the transition from meiosis to mitosis. Nature Reviews. Molecular Cell Biology. 2013;**14**:549-562 [19] Chambon JP et al. The PP2A inhibitor I2PP2A is essential for sister chromatid segregation in oocyte meiosis II. Current Biology. 2013;**23**:485-490

[20] Courtois A et al. The transition from meiotic to mitotic spindle assembly is gradual during early mammalian development. The Journal of Cell Biology. 2012;**198**:357-370

[21] Brezina PR et al. Preimplantation genetic testing for aneuploidy: What technology should you use and what are the differences? Journal of Assisted Reproduction and Genetics. 2016;**33**: 823-832

[22] Montag M et al. Polar body biopsy: A viable alternative to preimplantation genetic diagnosis and screening. Reproductive Biomedicine Online. 2009;**18**(Suppl. 1):6-11

[23] Geraedts J et al. Polar body array CGH for prediction of the status of the corresponding oocyte Part I: clinical results. Human Reproduction. 2011;**26**: 3173-3180

[24] Magli MC et al. Polar body array CGH for prediction of the status of the corresponding oocyte Part II: technical aspects. Human Reproduction. 2011;**26**: 3181-3185

[25] Verlinsky Y et al. Analysis of the first polar body: preconception genetic diagnosis. Human Reproduction. 1990;**5**:826-829

[26] Hou Y et al. Genome analyses of single human oocytes. Cell. 2013;**155**: 1492-1506

[27] Handyside AH et al. Multiple meiotic errors caused by predivision of chromatids in women of advanced maternal age undergoing in vitro fertilisation. European Journal of Human Genetics. 2012;**20**:742-747

[28] Harper J et al. What next for preimplantation genetic screening (PGS)? A position statement from the ESHRE PGD Consortium Steering Committee. Human Reproduction. 2010;**25**:821-823

[29] Fragouli E et al. Cytogenetic analysis of human blastocysts with the use of FISH, CGH and aCGH: Scientific data and technical evaluation. Human Reproduction. 2011;**26**:480-490

[30] Treff NR et al. Next generation sequencing-based comprehensive chromosome screening in mouse polar bodies, oocytes, and embryos. Biology of Reproduction. 2016;**94**:76

[31] Fragouli E et al. The cytogenetics of polar bodies: insights into female meiosis and the diagnosis of aneuploidy. Molecular Human Reproduction. 2011;**17**:286-295

[32] Sills ES et al. Determining parental origin of embryo aneuploidy: analysis of genetic error observed in 305 embryos derived from anonymous donor oocyte IVF cycles. Molecular Cytogenetics. 2014;**7**:68

[33] Templado C et al. Aneuploidy in human spermatozoa. Cytogenetic and Genome Research. 2011;**133**:91-99

[34] Pacchierotti F et al. Gender effects on the incidence of aneuploidy in mammalian germ cells. Environmental Research. 2007;**104**:46-69

[35] Chow JF et al. Array comparative genomic hybridization analyses of all blastomeres of a cohort of embryos from young IVF patients revealed significant contribution of mitotic errors to embryo mosaicism at the cleavage stage. Reproductive Biology and Endocrinology. 2014;**12**:105

[36] Ottolini CS et al. Genome-wide maps of recombination and chromosome segregation in human oocytes and embryos show selection for *Mechanisms of Aneuploidy DOI: http://dx.doi.org/10.5772/intechopen.101586*

maternal recombination rates. Nature Genetics. 2015;**47**:727-735

[37] Kuliev A et al. Meiosis errors in over 20,000 oocytes studied in the practice of preimplantation aneuploidy testing. Reproductive Biomedicine Online. 2011;**22**:2-8

[38] Feichtinger M et al. Increasing live birth rate by pre- implantation genetic screening of pooled polar bodies using array comparative genomic hybridization. PLoS One. 2015;**10**:e0128317

[39] Gabriel AS et al. Array comparative genomic hybridisation on first polar bodies suggests that non-disjunction is not the predominant mechanism leading to aneuploidy in humans. Journal of Medical Genetics. 2011;**48**: 433-437

[40] Fragouli E et al. The cytogenetics of polar bodies: insights into female meiosis and the diagnosis of aneuploidy. Molecular Human Reproduction. 2011;**17**:286-295

[41] Duncan FE et al. Chromosome cohesion decreases in human eggs with advanced maternal age. Aging Cell. 2012;**11**:1121-1124

[42] Zielinska AP et al. Sister kinetochore splitting and precocious disintegration of bivalents could explain the maternal age effect. eLife. 2015;**4**:e11389

[43] Patel J et al. Unique geometry of sister kinetochores in human oocytes during meiosis I may explain maternal ageassociated increases in chromosomal abnormalities. Biology Open. 2015;**5**: 178-184

[44] Sakakibara Y et al. Bivalent separation into univalents precedes age-related meiosis I errors in oocytes. Nature Communications. 2015;**6**:7550

[45] Zielinska AP et al. Sister kinetochore splitting and precocious disintegration

of bivalents could explain the maternal age effect. eLife. 2015;**4**:e11389

[46] Shomper M et al. Kinetochore microtubule establishment is defective in oocytes from aged mice. Cell Cycle. 2014;**13**:1171-1179

[47] Patel J et al. Unique geometry of sister kinetochores in human oocytes during meiosis I may explain maternal age-associated increases in chromosomal abnormalities. Biology Open. 2015;**5**: 178-184

[48] Sakakibara Y et al. Bivalent separation into univalents precedes age-related meiosis I errors in oocytes. Nature Communications. 2015;**6**:7550

[49] Lister LM et al. Age-related meiotic segregation errors in mammalian oocytes are preceded by depletion of cohesin and Sgo2. Current Biology. 2010;**20**:1511-1521

[50] Hunt P et al. Analysis of chromosome behavior in intact mammalian oocytes: Monitoring the segregation of a univalent chromosome during female meiosis. Human Molecular Genetics. 1995;**4**:2007-2012

[51] Nagaoka SI et al. Oocyte-specific differences in cellcycle control create an innate susceptibility to meiotic errors. Current Biology. 2011;**21**:651-657

#### **Chapter 3**

## The Unique Existence of Chromosomal Abnormalities in Polyploidy Plants

*Van Hieu Pham*

#### **Abstract**

Chromosomal abnormalities are a popular natural phenomenon, especially in polyploid plants, and their unique existence in plants is one of the major forces for speciation and evolution. This means that plants with existing chromosomal abnormalities developing through sexual and asexual pathways shed light on increasing biomass and adapting ecology. Regarding the former, plants with chromosomal abnormalities experience not only enlargement effects but also increased phytochemical compounds. As far as ecological perspectives are concerned, chromosomal abnormalities in plants enhance biotic and abiotic tolerance to climate change. This chapter focuses on chromosomal abnormalities in whole genome doubling, such as autopolyploid, allopolyploid, and aneuploidy plants, and discusses the effects and benefits of these abnormalities to evolution and ecological adaptation at the individual and population levels. It also discusses some advantages and disadvantages of polyploid animals in comparison with polyploid plants.

**Keywords:** chromosomal abnormality, polyploidy, evolution, climate change, reproduction

#### **1. Introduction**

Darwin's theory of natural selection maintains that the polymorphism that exhibits gross chromosomal alteration in plants as a way to reciprocally translocate along with changes in the segregation of pairs of chromosomes to ensure heterozygosity maintenance and limitation of the expression of lethal genes. Every day, living organisms ingest all kinds of food, taking in energy and nutrients to nourish, maintain, and develop their bodies. As such, food security is vitally important to survival. Attaining food security, however, has been a challenge. Potential solutions to food insecurity might lie in the genetic mechanisms regulating the reproductive process of plants. Different organisms reproduce in different ways, either via sexual combining of male and female gametes or asexually. Asexual reproduction generates a new plant by using parts of the parent plants. Some artificial asexual reproduction methods include grafting, layering, and micropropagation. Genetic identicalness to the progenitor plant is an outstanding feature of plants produced asexually. Reproductive chromosome abnormalities derive from mistaking meiosis and mitosis occur [1]. For instance, observing meiotic processes revealed evidence that the trio of genes *SMG7*, *SDS*, and *MS5* interrelated with both other chromatin organizing factors and proteins functioning DNA repair-related, involved in *MSH6*

and *DAYSLEEPER*. The convergent tasks detected (other meiotic pathways, chromosome arrangement or remodeling, ABA cues and ion transport) offer insights into the challenges of polyploidization. Investigation of the meiosis of autotetraploid potato *Solanum tuberosum* revealed a variety of challenges in correct segregation and recombination of multiple homologous chromosomes that constrain meiotic chromosomal configuration [2].

With advances in genetic engineering and continual elucidation of genes governing the reproductive pathway, humanity is on the verge of being able to control the expression and regulation of these genes [1, 3]. Key genes related to flowering, such as *CO*, *CRY2*, *FT*, *FPF1*, *FD*, *GA1*, and *ELA1*, have already been studied [3]. Scientists and breeders worldwide use biotechnology to study reproductive processes in laboratories and field trials. Sustainable agricultural development is required to increase crop diversity, stabilize yield, and increase resilience via the accelerated development of several crops containing desired traits that have the capacity to adapt to and mitigate consequences from climate change [4, 5].

In terms of biodiversity, speciation, and evolution, there are thousands of existing plant species that can adapt to various topographies and climates. This means that plant species not only increase the abundance of genetics but also enhance the ability to adapt to boost genome evolution in harsh environments [1, 6]. The best examples are those that involve autopolyploids, allopolyploids, and aneuploidy. There are more than 4000 potato varieties, including more than 180 wild potato relatives [7]. More specifically, potato, one of the most multifaceted genetic modes with a variety of ploidy levels, such as 76%, recognizes diploids, 3% triploids, 12% tetraploids, 2% pentaploids, and 7% hexaploids, among which the highest yield is tetraploid due to a further level of genetic heterogeneity [8–10]. Based on practical empirical proof, two clusters of cultivated potato have been categorized: the Andigenum group located in the high Andes of northern and central South America that exhibit a wide range of ploidy levels, and the Chilotanum group from the lowlands of southern Chile, which are tetraploids [11].

Plant karyotypes at individual, species, and genera levels exhibit an abnormal number of chromosomes. A typical example is Chayote (*Saccharum edule* (Jacq.) Sw.) with variable chromosome numbers of 12, 13, and 14 resulting from cytological analysis [12], as shown in **Table 1**.

This chapter focuses on chromosomal abnormalities in whole genome doubling, such as autopolyploid, allopolyploid, and aneuploidy plants, and then discusses the effects and benefits of these abnormalities to evolution and ecological adaptation at the individual and population levels. It also discusses some advantages and disadvantages of polyploid animals in comparison with polyploid plants.


#### **Table 1.**

*Summary of plant species with chromosomal abnormalities.*

#### **2. Chromosomal abnormalities affect giant effects and alternative natural secondary metabolites**

That chromosomal abnormality outranks other plants in terms of parts of plant size and biochemical compounds characteristically states that gene regulation plays an important role. Regarding the upregulation of genes, cell division and cell expansion are related to genes such as ARGOS, *ANT* (*AITEGUMENTA*), *CYCD3;1*, *Growth Regulating Factor 1* (*AtGRF1*) and *EXPASIN 10* (*AtEXPA10*) [27–29], *EXPB3*, and *TCP* [30]. Alongside these genes, lipid transport genes such as *wbc11–2* and *cer5–2* are a way to make large autotetraploid plants [31–33]. Moreover, proteins involved in cell proliferation, glutathione metabolic pathways, and cellulose, chlorophyll, pectin, and lignin synthesis play a role in enlarging plant size [34, 35]. Cytosine methylation in the whole genome also contributes to changes in organ size in polyploid plants, which can effectively improve potential and complex agronomic traits in many crops [36, 37]. Cell size in polyploid plants plays an important role in changing phenotypes [38]. Enlarged organ size due to chromosomal abnormalities usually leads to increased yield and production of cultivated plants [39]. Studying autotetraploid *Vicia cracca* L. revealed that seed size and germination of tetraploids are more dominant than diploid seeds [40]. Although chromosomal abnormalities lead to large plants, autotetraploid birch plants (*Betula platyphylla*) and apple plants (*Malus domestica*) have a dwarf phenotype caused by reduced growth regulation signals [41, 42].

Similarly, chromosomal abnormalities also alter secondary metabolites, especially phytochemical compounds, in several plant species [43]. For example, natural components observed in tetrasomic tetraploid opium poppy (*Papaver somniferum* L.) enhanced morphine content by 25–50% by changing the expression of several genes regulating the alkaloid biosynthesis pathway [44]. Another example is cytosine methylation occurring genome-wide, enhancing phytochemicals in autotetraploid cymbopogons [36]. The autotetraploid *Arabidopsis thaliana* Col-0 alters metabolites and genes regulating tricarboxylic acid cycle (TCA) and gamma-Aminobutyric acid (GABA) compared with diploids [45]. Lycopene significantly increased autotriploid watermelons because of a regulation of phytohormones on metabolic pathways and upregulation of genes controlling biosynthetic lycopene [46]. Interestingly, polyploidization is a promising approach for gaining significant value, especially with medicinal plants, by producing secondary metabolites [43]. For example, upregulating genes contributing to the biosynthesis pathway of podophyllotoxin (PTOX) in autotetraploid *Linum album* enhanced the content of PTOX [47]. Vitamin A enrichment in triploid banana has been initiated by inducing tetraploids from several types of diploids and then creating hybrids [48]. Many total flavonoids and gastrodin are produced in autotetraploid *Anoectochilus formosanus* Hayata [49]. The tetraploid type of *Physalis angutala* Linn. from Rajasthan alters palmitic acid, linoleic acid, and linolenic acid [50]. In the last decade, many plant studies have given objects based on the outstanding benefits of chromosomal abnormalities. Those breeders have been observing chromosomal abnormalities as a way to gain elite plant cultivars because an increase in plant organ size is derived from some of the most significant consequences of chromosomal abnormalities [51, 52].

The chromosomal abnormality of the level of ploidy variation is useful for breeding both within and among autopolyploid and allopolyploid plant species [25]. Another view is that chromosomal abnormalities contribute to plants' ability to withstand detrimental environmental conditions. As far as the first idea is concerned, a chromosomal abnormality is not appropriate for sexual reproduction in aneuploidy due to chromosomal abnormalities in gametes. Another utilization

of polyploidy is that grafted crops can use artificial polyploidy as parts of rootstock and scion with potential agronomic traits in the context of climate variability [53].

#### **3. Chromosomal abnormalities enhance abiotic and biotic stress tolerance**

Chromosomal abnormalities in plants enhance both biotic and abiotic stress tolerance. For example, many studies have proven that several pathways respond to salinity stress. Chromosomally abnormal flora use several processes to adapt to high salt concentration conditions, including accumulating Na+ extrusion in roots, increasing Na+ transport to leaves, regulating osmotics, enhancing gene expression related to antioxidants, mitigating reactive oxygen species (ROS), photosynthesizing cues, changing SNP markers related to salt stress, upregulating aquaporin genes, phytohormone transduction cues, protein processing, regulating transcription factors, upregulating ATP synthase to enhance ion transport and changing protons, and using miRNAs [54–63]. Chromosomally abnormal plants can also adapt to water insufficiency through miRNA mechanisms and target genes controlling transcriptional regulation, hormone metabolism, and plant defense. An increase in abscisic acid (ABA) content in response to drought stress in several polyploid plants such as *Paulownia fortunei*, *P. australis*, *P. tomentosa*, and *Lycium ruthenicum* has been observed [64–69]. Antioxidant defense systems were activated to sufficiently support heat tolerance in *Dioscorea* and *Arabidopsis* [70, 71]. Plants with chromosomal abnormalities might tolerate cold stress by growing antioxidants and epigenetics [72, 73]. Changing root anatomical characteristics supports autotetraploids to adapt to high concentrations of boron in soil and enhance Cu transport genes. Activation of antioxidation defense and positive regulation of ABA-responsive gene expression are ways to survive in environments containing high concentrations of copper [74, 75]. Enhancing the expression of target genes that regulate proline biosynthesis to support autopolyploid birch plants (*B. platyphylla*) in NaHCO3 stress tolerance has been investigated [76]. In addition, biotic resistance was demonstrated in autotetraploid *Malus* × *domestica* and *Solanum chacoense*. More specifically, significantly increasing the *Rvi6* resistance gene locus was observed as a way to assist autopolyploids in enhancing *Venturia* resistance [77]. Similarly, autotetraploid potato has the capacity of common scab resistance by crossing 2n gametes from the diploid *S. chacoense* [78].

#### **4. Chromosomal abnormalities help plants adapt to ecological invasion and climate variability**

Chromosomal abnormalities are one of the major adaptation ecologies and climate changes, such as fixing on growth, potential morphological traits and ecological invasion, pollinators, and the factors supporting pollination in nature [79]. After appearance of chromosomal abnormality in some rare cases, the increasing cell size leads to alteration of physiological manners with their environmental condition, augmenting multiple novel alleles and changing regulatory pathways to create new potentially beneficial phenotypic variations. For instance, studying the transcriptome in aneuploidy maize revealed qualitative changes in gene expression in comparison to wild-type plants [80]. The number of expanding ecological spaces to polyploid plants has been recorded in various studies [81]. Polyploid *A. thaliana* is a plant with adaptive potential caused by the increased resources of transposable

#### *The Unique Existence of Chromosomal Abnormalities in Polyploidy Plants DOI: http://dx.doi.org/10.5772/intechopen.99821*

element (TE) insertions at higher ploidy levels and enhanced gene expression related to reproduction [82, 83]. Several studies have proven that chromosomal abnormalities adapt to ecological invasion and climate variation. For example, biological invasions in *Brassicaceae* proved to be evolutionary processes to adapt and widespread in central Europe [84]. Another example is that of the native range of distribution of *Lythrum salicaria*. Several cytotypes with 2×, 3×, 4×, and 6× variations are found in regions of the Middle East, while only tetraploids are located in North America. In addition, the invasive spread of North American populations lacks differences in ploidy level [85]. Studying potato germplasm demonstrated markers related to unique geographic identity associated with traits of abiotic stress tolerance [86]. One of the priorities in genotype development is to gain stress tolerance and beneficial nutritional aspects as a way to reduce the effects of climate change [87, 88]. The view is that polyploidization contributes to better adaptation to the environment in terms of suitability for growth and other benefits of cell size. Breeders and human beings can benefit immensely from more ecological adaptation after chromosomal abnormality since it improves potential traits being exploited for breeding experiments.

For the most part, polyploidy is probably less popular in the animal kingdom than in the plant kingdom. More specifically, polyploids have been observed in amphibia (African clawed frog, *Xenopus* spp.), and different species of fishes exist [89]. This is because the polyploid animal species can overcome meiosis and exhibit parthenogenesis in which an egg cell can develop into an individual without fertilization. In addition, polyploid animal kingdoms are similar to polyploid plant kingdoms. They both have beneficial and detrimental effects and are the reason for meiotic imbalance. The greatest advantage of polyploid animals is that polyploid offspring are shielded from the deleterious effects of recessive mutations. However, chromosomal abnormalities may lead to congenital diseases and pregnancy loss in animals, especially in humans. Regarding meiotic imbalance, spindle irregularities might occur in polyploids, resulting in chaotic segregation of chromatids and aneuploid cells. An abnormal number of chromosomes in aneuploid cells might result in three or more sets of chromosomes produced in meiosis being different from diploid cells. This can explain why polyploid animals could form multiple arrangements of homologous chromosomes in metaphase I, resulting in abnormal or random segregation to produce aneuploid gametes or to form imbalanced gametes [89, 90].

#### **5. Conclusion**

It is unquestionable whether chromosomal abnormalities derived from sex or asexual reproduction are essential for the successful existence of organisms on this planet. With climate variability becoming more alarming than ever, chromosomal abnormality has been occurring naturally as a way to address the issue of food security by expanding breeding opportunities to develop seedless triploid plants, increase ornamental features, increase environmental tolerance, enhance biomass, and more. Chromosomal abnormalities are also vital to human beings mainly because their exploration can open opportunities for securing food security. For example, breeders who are experienced in hybrid development are more likely to find desired agronomic traits. More importantly, several breeders today require at least a desired trait of novel crops before considering using them for production. Chromosomal abnormalities are essential for success in adapting ecology and play a vital role in evolution due to generating variation in a natural population.

### **Acknowledgements**

The author thanks the financial support and convenient conditions from HCMC Biotechnology Center.

#### **Author details**

Van Hieu Pham Biotechnology Center of Ho Chi Minh, Ho Chi Minh City, Vietnam

\*Address all correspondence to: hieupvbio@gmail.com

© 2021 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

*The Unique Existence of Chromosomal Abnormalities in Polyploidy Plants DOI: http://dx.doi.org/10.5772/intechopen.99821*

#### **References**

[1] Bohutinska M, Alston M, Monnahan P, Mandakova T, Bray S, Paajanen P, et al. Novelty and convergence in adaptation to whole genome duplication. Molecular Biology and Evolution. 2021. DOI: 10.1093/ molbev/msab096

[2] Choudhary A, Wright L, Ponce O, Chen J, Prashar A, Sanchez-Moran E, et al. Varietal variation and chromosome behavior during meiosis in *Solanum tuberosum*. Heredity. 2020;**125**:212-226. DOI: 10.1038/s41437-020-0328-6

[3] Braynen J, Yang Y, Yuan J, Xie Z, Cao G, Wei X, et al. Comparative transcriptome analysis revealed differential gene expression in multiple signaling pathways at flowering in polyploidy *Brassica rapa*. Cell & Bioscience. 2021;**11**:17. DOI: 10.1186/s13578-021-00528-1

[4] Abberton M, Batley J, Bentley A, Bryant J, Cai H, Cockram J, et al. Global agricultural intensification during climate change: A role for genomics. Plant Biotechnology Journal. 2016;**14**: 1095-1098. DOI: 10.1111/pbi.12467

[5] Touchell DH, Palmer IE, Ranney TG. *In vitro* ploidy manipulation for crop improvement. Frontiers in Plant Science. 2020;**11**:722. DOI: 10.3389/ fpls.2020.00722

[6] Storme ND, Mason A. Plant speciation through chromosome instability and ploidy change: Cellular mechanisms, molecular factors and evolutionary relevance. Current Plant Biology. 2014;**1**:10-33

[7] Machida-Hirano R. Diversity of potato genetic resources. Breeding Science. 2015;**65**:26-40. DOI: 10.1270/ jsbbs.65.26

[8] Hawkes JG. The potato: Evolution, biodiversity and genetic resources. American Potato Journal. 1990;**67**: 733-735. DOI: 10.1007/BF03044023

[9] Watanabe KN. Potato genetics, genomics, and applications. Breeding Science. 2015;**65**:53-68. DOI: 10.1270/ jsbbs.65.53

[10] Muthoni J, Kabira J, Shimelis H, Melis R. Tetrasomic inheritance in cultivated potato and implications in conventional breeding. Australian Journal of Crop Science. 2015;**9**:185-190

[11] Jansky SH, Spooner DM. The evolution of potato breeding. Plant Breeding Reviews. 2018;**41**:169-214. DOI: 10.1002/9781119414735

[12] Olvera-Vazquez S, Cadena-Iñiguez J, Gilani S, Watanabe K. The cytological studies on neglected and underutilized cucurbit species with special reference to Chayote, an under-exploited species. American Journal of Plant Sciences. 2019;**10**(8):1261-1279. DOI: 10.4236/ ajps.2019.108091

[13] Lira-Saade R. Chayote. Sechiumedule (Jacq.) Sw. Promoting the Conservation and Use of Underutilized and Neglected Crops. Rome: Institute of Plant Genetics and Crop Plant Research; 1996

[14] De Donato M, Cequea H. A cytogenetic study of six cultivars of the Chayote, *Sechium edule* Sw. (Cucurbitaceae). Journal of Heredity. 1994;**85**:238-241. DOI: 10.1093/ oxfordjournals.jhered.a111444

[15] Mercado P, Lira R. Contribucion al conocimiento de los numerous cromosomicos de los generos Sechium P. BR. Y Sicana Naudin (*Cucurbitaceae*). Acta Botanica Mexicana. 1994;**27**:7-13. DOI: 10.21829/abm27.1994.706

[16] Bisognin DA. Origin and evolution of cultivated cucurbits. Ciencia Rural. 2002;**32**:715-723. DOI: 10.1590/ S0103-84782002000400028

[17] Varghese RM. Cytology of *Sechium edule* Sw. Current Science. 1973;**42**:30

[18] eFloras. 11. *Curcuma* Linnaeus. In: Flora of China. Vol. Vol. 24. St. Louis, MO/Cambridge, MA: Missouri Botanical Garden/Harvard University Herbaria; 2020. p. 359. Available from: http://www.efloras.org

[19] Wu DL, Larsen K. Zingiberaceae. In: Wu ZY, Raven P, Hong DY, editors. Flora of China. Vol. 24. Beijing, China/ St. Louis, MO: Science Press/Missouri Botanical Garden Press; 2000. pp. 322-377

[20] Leong-Skornickova J, Newman M. Gingers of Cambodia, Laos and Vietnam. Singapore: Singapore Botanic Gardens; 2015

[21] Larsen K. A preliminary checklist of the *Zingiberaceae* of Thailand. Thai Forest Bulletin (Botany). 1996;**24**:35-49

[22] Leong-Skornickova J, Sida O, Jarolimova V, Sabu M, Fer T, Travnicek P, et al. Chromosome numbers and genome size variation in Indian species of *Curcuma* (Zingiberaceae). Annals of Botany. 2007;**100**:505-526

[23] Maknoi C. Taxonomy and phylogeny of the genus *Curcuma* L. (Zingiberaceae) with particular reference to its occurrence in Thailand [PhD thesis]. Thailand: Prince of Songkla University; 2006

[24] eFloras. 20. Zingiberaceae Lindley. In: Flora of China. Vol. Vol. 24. St. Louis, MO/Cambridge, MA: Missouri Botanical Garden/Harvard University Herbaria; 2020. p. 322. Available from: http://www.efloras.org

[25] Hojsgaard D, Honfi AI, Rua G, Daviña J. Chromosome numbers and ploidy levels of *Paspalum* species from subtropical South America (Poaceae). Genetic Resources and Crop Evolution. 2009;**56**:533-545. DOI: 10.1007/ s10722-008-9384-0

[26] Hodálová I, Mered'ajun P, Vinikarová A, Grulich V, Rotreklová O. A new cytotype of *Jacobaea vulgaris* (Asteraceae): Frequency, morphology and origin. Nordic Journal of Botany. 2010;**28**:413-427. DOI: 10.1111/ j.1756-1051.2010.00603.x

[27] Gu AX, Zhao JJ, Li LM, Wang YH, Zhao YJ, Hua F, et al. Analyses of phenotype and ARGOS and ASY1 expression in a ploidy Chinese cabbage series derived from one haploid. Breeding Science. 2016;**66**(2):161-168. DOI: 10.1270/jsbbs.66.161

[28] Wang B, Sang Y, Song J, Gao XQ, Zhang X. Expression of a rice *OsARGOS* gene in *Arabidopsis* promotes cell division and expansion and increases organ size. Journal of Genetics and Genomics. 2009;**36**(1):31-40. DOI: 10.1016/s1673-8527(09)60004-7

[29] Allario T, Brumos J, Colmenero-Flores JM, Tadeo F, Froelicher Y, Talon M, et al. Large changes in anatomy and physiology between diploid Rangpur lime (*Citrus limonia*) and its autotetraploid are not associated with large changes in leaf gene expression. Journal of Experimental Botany. 2011;**62**(8):2507-2519. DOI: 10.1093/jxb/erq467

[30] Qiao G, Liu M, Song K, Li H, Yang H, Yin Y, et al. Phenotypic and comparative transcriptome analysis of different ploidy plants in *Dendrocalamus latiflorus* Munro. Frontiers in Plant Science. 2017;**8**:1371. DOI: 10.3389/ fpls.2017.01371

[31] Bird D, Beisson F, Brigham A, Shin J, Greer S, Jetter R, et al. Characterization of *Arabidopsis* ABCG11/WBC11, an ATP binding cassette (ABC) transporter that is required for cuticular lipid secretion. Plant Journal. 2007;**52**(3):485-498. DOI: 10.1111/j.1365-313X.2007.03252.x

[32] Narukawa H, Yokoyama R, Komaki S, Sugimoto K, Nishitani K. Stimulation of cell elongation by tetraploidy in hypocotyls of dark grown *The Unique Existence of Chromosomal Abnormalities in Polyploidy Plants DOI: http://dx.doi.org/10.5772/intechopen.99821*

*Arabidopsis* seedlings. PLoS One. 2015;**10**(8):e0134547. DOI: 10.1371/ journal.pone.0134547

[33] Narukawa H, Yokoyama R, Nishitani K. Possible pathways linking ploidy level to cell elongation and cuticular function in hypocotyls of dark-grown *Arabidopsis* seedlings. Plant Signaling & Behavior. 2016;**11**(2): e1118597. DOI: 10.1080/15592324. 2015.1118597

[34] Zhou Y, Kang L, Liao S, Pan Q, Ge X, Li Z. Transcriptomic analysis reveals differential gene expressions for cell growth and functional secondary metabolites in induced autotetraploid of Chinese woad (*Isatis indigotica* fort.). PLoS One. 2015;**10**(3):e0116392. DOI: 10.1371/journal.pone.0116392

[35] Wang Z, Fan G, Dong Y, Zhai X, Deng M, Zhao Z, et al. Implications of polyploidy events on the phenotype, microstructure, and proteome of *Paulownia australis*. PLoS One. 2017;**12**(3):e0172633. DOI: 10.1371/ journal.pone.0172633

[36] Lavania UC, Srivastava S, Lavania S, Basu S, Misra NK, Mukai Y. Autopolyploidy differentially influences body size in plants, but facilitates enhanced accumulation of secondary metabolites, causing increased cytosine methylation. The Plant Journal. 2012;**71**(4):539-549. DOI: 10.1111/ j.1365-313X.2012.05006.x

[37] Ding M, Chen ZJ. Epigenetic perspectives on the evolution and domestication of polyploid plant and crops. Current Opinion in Plant Biology. 2018;**42**:37-48. DOI: 10.1016/j. pbi.2018.02.003

[38] Doyle JJ, Coate JE. Polyploidy, the nucleotype, and novelty: The impact of genome doubling on the biology of the cell. International Journal of Plant Sciences. 2019;**180**(1):1-52. DOI: 10.1086/ 700636

[39] Alam H, Razaq M, Salahuddin. Induced polyploidy as a tool for increasing tea (*Camellia sinensis* L.) production. Journal of Northeast Agricultural University (English Edition). 2015;**22**(3):43-47. DOI: 10.1016/ S1006-8104(16)30005-8

[40] Eliášová A, Műnzbergová Z. Higher seed size and germination rate may favor autotetraploids of *Vicia cracca* L. (Fabaceae). Biological Journal of the Linnean Society. 2014;**113**:57-73

[41] Mu H, Liu Z, Lin L, Li H, Jiang J, Liu G. Transcriptomic analysis of phenotypic changes in birch (*Betula platyphylla*) autotetraploids. International Journal of Molecular Sciences. 2012;**13**(10):13012-13029. DOI: 10.3390/ijms131013012

[42] Ma Y, Xue H, Zhang L, Zhang F, Ou C, Wang F, et al. Involvement of auxin and brassinosteroid in dwarfism of autotetraploid apple (*Malus* × *domestica*). Scientific Reports. 2016;**6**:26719. DOI: 10.1038/srep26719

[43] Gantait S, Mukherjee E. Induced autopolyploidy—A promising approach for enhanced biosynthesis of plant secondary metabolites: An insight. Genetic Engineering and Biotechnology. 2021;**19**:4. DOI: 10.1186/s43141-020- 00109-8

[44] Mishra B, Pathak S, Sharma A, Trivedi P, Shukla S. Modulated gene expression in newly synthesized autotetraploid of *Papaver somniferum* L. South African Journal of Botany. 2010;**76**(3):447-452. DOI: 10.1016/j. sajb.2010.02.090

[45] Vergara F, Kikuchi J, Breuer C. Artificial autopolyploidization modifies the tricarboxylic acid cycle and GABA shunt in *Arabidopsis thaliana* Col-0. Scientific Reports. 2016;**6**:26515. DOI: 10.1038/srep26515

[46] Dou J, Yuan P, Zhao S, He N, Zhu H, Gao L, et al. Effect of ploidy level on

expression of lycopene biosynthesis genes and accumulation of phytohormones during watermelon (*Citrullus lanatus*) fruit development and ripening. Journal of Integrative Agriculture. 2017;**16**(9):19561967. DOI: 10.1016/S2095-3119(16)61618-0

[47] Javadian N, Karimzadeh G, Sharifi M, Moieni A, Behmanesh M. *In vitro* polyploidy induction: Changes in morphology, podophyllotoxin biosynthesis, and expression of the related genes in *Linum album* (*Linaceae*). Planta. 2017;**245**(6):1165- 1178. DOI: 10.1007/s00425-017-2671-2

[48] Amah D, van Biljon A, Maziya-Dixon B, Labuschagne M, Swennen R. Effects of in vitro polyploidization on agronomic characteristics and fruit carotenoid content: Implications for banana genetic improvement. Frontiers in Plant Science. 2019;**10**:1450. DOI: 10.3389/ fpls.2019.01450

[49] Chung HH, Shi SK, Huang B, Chen JT. Enhanced agronomic traits and medicinal constituents of autotetraploids in *Anoectochilus formosanus* Hayata, a top-grade medicinal orchid. Molecules. 2017;**22**(11). DOI: 10.3390/ molecules22111907

[50] Preet R, Gupta RC. Fatty acid profiling in diploid (n=12) and tetraploid cytotypes (n=24) of *Physalis angulata* Linn. from Rajasthan by gas chromatography. International Journal of Pharmaceutical Sciences and Research. 2017;**8**(8):3458-3462

[51] Catalano C, Abbate L, Motisi A, Crucitti D, Cangelosi V, Pisciotta A, et al. Autotetraploid emergence via somatic embryogenesis in *Vitis vinifera* induces marked morphological changes in shoots, mature leaves, and stomata. Cell. 2021;**10**:1336. DOI: 10.3390/ cells10061336

[52] Sattler MC, Carvalho CR, Clarindo WR. The polyploidy and its key role in plant breeding. Planta. 2015. DOI: 10.1007/s00425-015-2450-x

[53] Ruiz M, Oustric J, Santini J, Morillon R. Synthetic polyploidy in grafted crops. Frontiers in Plant Science. 2020;**11**:540894. DOI: 10.3389/ fpls.2020.540894

[54] Meng H, Jiang S, Hua S, Lin X, Li Y, Guo W, et al. Comparison between a tetraploid turnip and its diploid progenitor (*Brassica rapa* L.): The adaptation to salinity stress. Agricultural Sciences in China. 2013;**10**(3):363-375. DOI: 10.1016/ S1671-2927(11)60015-1

[55] Tu Y, Jiang A, Gan L, Hossain M, Zhang J, Peng B, et al. Genome duplication improves rice root resistance to salt stress. Rice. 2014;**7**(1):15-15. DOI: 10.1186/s12284-014-0015-4

[56] Xue H, Zhang F, Zhang Z, Fu J, Wang F, Zhang B, et al. Differences in salt tolerance between diploid and autotetraploid apple seedlings exposed to salt stress. Scientia Horticulturae. 2015;**190**:24-30. DOI: 10.1016/j. scienta.2015.04.009

[57] Yan K, Wu C, Zhang L, Chen X. Contrasting photosynthesis and photoinhibition in tetraploid and its autodiploid honeysuckle (*Lonicera japonica* Thunb.) under salt stress. Frontiers in Plant Science. 2015;**6**:227. DOI: 10.3389/fpls.2015.00227

[58] Fan G, Li X, Deng M, Zhao Z, Yang L. Comparative analysis and identification of miRNAs and their target genes responsive to salt stress in diploid and tetraploid *Paulownia fortunei* seedlings. PLoS One. 2016;**11**(2):e0149617. DOI: 10.1371/ journal.pone.0149617

[59] Fan G, Wang L, Deng M, Zhao Z, Dong Y, Zhang X, et al. Changes in transcript related to osmosis and intracellular ion homeostasis in

*The Unique Existence of Chromosomal Abnormalities in Polyploidy Plants DOI: http://dx.doi.org/10.5772/intechopen.99821*

*Paulownia tomentosa* under salt stress. Frontiers in Plant Science. 2016;**7**:384. DOI: 10.3389/fpls.2016.00384

[60] Yu L, Liu X, Boge W, Liu X. Genome-wide association study identifies loci for salt tolerance during germination in autotetraploid alfalfa (*Medicago sativa* L.) using genotyping by-sequencing. Frontiers in Plant Science. 2016;**7**:956. DOI: 10.3389/ fpls.2016.00956

[61] Deng M, Dong Y, Zhao Z, Li Y, Fan G. Dissecting the proteome dynamics of the salt stress induced changes in the leaf of diploid and autotetraploid *Paulownia fortunei*. PLoS One. 2017;**12**(7):e0181937. DOI: 10.1371/ journal.pone.0181937

[62] Liu B, Sun G. microRNAs contribute to enhanced salt adaptation of the autopolyploid *Hordeum bulbosum* compared with its diploid ancestor. Plant Journal. 2017;**91**(1):57-69. DOI: 10.1111/tpj.13546

[63] Zhao Z, Li Y, Liu H, Zhai X, Deng M, Dong Y, et al. Genome-wide expression analysis of salt-stressed diploid and autotetraploid *Paulownia tomentosa*. PLoS One. 2017;**12**(10): e0185455. DOI: 10.1371/journal. pone.0185455

[64] del Pozo JC, Ramirez-Parra E. Deciphering the molecular bases for drought tolerance in *Arabidopsis* autotetraploids. Plant, Cell and Environment. 2014;**37**(12):2722-2737. DOI: 10.1111/pce.12344

[65] Niu S, Wang Y, Zhao Z, Deng M, Cao L, Yang L, et al. Transcriptome and degradome of microRNAs and their targets in response to drought stress in the plants of a diploid and its autotetraploid *Paulownia australis*. PLoS One. 2016;**11**(7):e0158750. DOI: 10.1371/ journal.pone.0158750

[66] Cao X, Fan G, Cao L, Deng M, Zhao Z, Niu S, et al. Drought stressinduced changes of microRNAs in

diploid and autotetraploid *Paulownia tomentosa*. Genes & Genomics. 2017;**39**(1):77-86. DOI: 10.1007/ s13258-016-0473-8

[67] Zhao Z, Niu S, Fan G, Deng M, Wang Y. Genome-wide analysis of gene and microRNA expression in diploid and autotetraploid *Paulownia fortunei* (Seem) Hemsl. under drought stress by transcriptome, microRNA, and degradome sequencing. Forests. 2018;**9**(2):88. DOI: 10.3390/f9020088

[68] Rao S, Tian Y, Xia X, Li Y, Chen J. Chromosome doubling mediates superior drought tolerance in *Lycium ruthenicum* via abscisic acid signaling. Horticulture Research. 2020;**7**:40. DOI: 10.1038/s41438-020-0260-1

[69] Li M, Zhang C, Hou L, Yang W, Liu S, Pang X, et al. Multiple responses contribute to the enhanced drought tolerance of the autotetraploid *Ziziphus jujuba* Mill. var. *spinosa*. Cell & Bioscience. 2021;**11**:119. DOI: 10.1186/ s13578-021-00633-1

[70] Zhang XY, Hu CG, Yao JL. Tetraploidization of diploid *Dioscorea* results in activation of the antioxidant defense system and increased heat tolerance. Journal of Plant Physiology. 2010;**167**(2):88-94. DOI: 10.1016/j. jplph.2009.07.006

[71] DeBolt S. Copy number variation shapes genome diversity in *Arabidopsis* over immediate family generational scales. Genome Biology and Evolution. 2010;**2**:441-453. DOI: 10.1093/ gbe/evq033

[72] Deng B, Du W, Changlai L, Sun W, Tian S, Dong H. Antioxidant response to drought, cold and nutrient stress in two ploidy levels of tobacco plants: Low resource requirement confers polytolerance in polyploids. Plant Growth Regulation. 2012;**66**(1):37-47. DOI: 10.1007/s10725-011-9626-6

[73] Syngelaki E, Daubert M, Klatt S, Hörandl E. Phenotypic responses,

reproduction mode and epigenetic patterns under temperature treatments in the alpine plant species *Ranunculus kuepferi* (*Ranunculaceae*). Biology. 2020;**9**:315. DOI: 10.3390/biology 9100315

[74] Ruiz M, Quiñones A, Martínez Alcántara B, Aleza P, Morillon R, Navarro L, et al. Tetraploidy enhances boron-excess tolerance in Carrizo Citrange (*Citrus sinensis* L. Osb. × *Poncirus trifoliata* L. Raf.). Frontiers in Plant Science. 2016;**7**:701. DOI: 10.3389/ fpls.2016.00701

[75] Li M, Xu G, Xia X, Wang M, Yin X, Zhang B, et al. Deciphering the physiological and molecular mechanisms for copper tolerance in autotetraploid *Arabidopsis*. Plant Cell Reports. 2017;**36**(10):1585-1597. DOI: 10.1007/s00299-017-2176-2

[76] Mu H, Lin L, Zhang Q, Tang X, Zhang X, Cheng G. Growth, proline content and proline-associated gene expression of autotetraploid *Betula platyphylla* responding to NaHCO3 stress. Dendrobiology. 2016;**75**:123-129. DOI: 10.12657/denbio.075.012

[77] Hias N, Svara A, Wannes Keulemans J. Effect of polyploidisation on the response of apple (*Malus* × *domestica* Borkh.) to *Venturia inaequalis* infection. European Journal of Plant Pathology. 2018;**151**(2):515-526. DOI: 10.1007/s10658-017-1395-2

[78] Jansky S, Haynes K, Douches D. Comparison of two strategies to introgress genes for resistance to common scab from diploid *Solanum chacoense* into tetraploid cultivated potato. American Journal of Potato Research. 2019;**96**:255-261. DOI: 10.1007/s12230-018-09711-6

[79] Ramsey J, Ramsey TS. Ecological studies of polyploidy in the 100 years following its discovery. Philosophical Transactions of the Royal Society B.

2014;**369**:20130352. DOI: 10.1098/ rstb.2013.0352

[80] Makarevitch I, Harris C. Aneuploidy causes tissue-specific qualitative changes in global gene expression patterns in maize. Plant Physiology. 2010;**152**:927-938. DOI: 10.1104/pp.109.150466

[81] Spoelhof JP, Soltis PS, Soltis DE. Pure polyploidy: Closing the gaps in autopolyploid research. Journal of Systematics and Evolution. 2017;**55**(4): 340-352. DOI: 10.1111/jse.12253

[82] Bohutínská M, Alston M, Monnahan P, Mandáková T, Bray S, Paajanen P, et al. Novelty and convergence in adaptation to whole genome duplication. Molecular Biology and Evolution. 2021:msab096. DOI: 10.1093/molbev/msab096

[83] Baduel P, Quadrana L, Hunter B, Bomblies K, Colot V. Relaxed purifying selection in autopolyploids drives transposable element overaccumulation which provides variants for local adaptation. Nature Communications. 2019;**10**:5818. DOI: 10.1038/ s41467-019-13730-0

[84] Hurka H, Bleeker W, Neuffer B. Evolutionary processes associated with biological invasions in the Brassicaceae. Biological Invasions. 2003;**5**:281-292

[85] Kubátová B, Trávníček P, Bastlová D, Čurn V, Jarolímová V, Suda J. DNA ploidy-level variation in native and invasive populations of *Lythrum salicaria* at a large geographical scale. Journal of Biogeography. 2008;**35**: 167-176

[86] del Rio AH, Bamberg JB. Detection of adaptive genetic diversity in wild potato populations and its implications in conservation of potato germplasm. American Journal of Plant Sciences. 2020;**11**:1562-1578. DOI: 10.4236/ ajps.2020.1110113

*The Unique Existence of Chromosomal Abnormalities in Polyploidy Plants DOI: http://dx.doi.org/10.5772/intechopen.99821*

[87] Fox DT, Soltis DE, Soltis PS, Ashman TL, de Peer YV. Polyploidy: A biological force from cells to ecosystems. Trends in Cell Biology. 2020. DOI: 10.1016/j.tcb.2020.06.006

[88] Campos H, Ortiz O. The Potato Crop: Its Agricultural, Nutritional and Social Contribution to Humankind2020. DOI: 10.1007/978-3-030-28683-5

[89] Stenberg P, Saura A. Meiosis and its deviations in polyploid animals. Cytogenetic and Genome Research. 2013;**140**:185-203. DOI: 10.1159/ 000351731

[90] Comai L. The advantages and disadvantages of being polyploid. Nature. 2005;**6**:836-846. DOI: 10.1038/ nrg1711

### Section 3
