**4. Mutant crop varieties and their impact on food security**

Mutation breeding techniques especially gamma and other physical mutagens have helped in generating a large number of mutants and generated a massive quantity of genetic variability that is significantly employed in the studies from plant breeding and genetics and in modern studies (genomics) (**Figure 4**). The mutants are released directly as varieties or furnish as a basic resource in the breeding programs to create genetic variation. The released mutant varieties offer higher yields, disease-resistant, improved quality, and resilient to environmental swings. A huge number of these mutant cultivars have been released in developing regions boosting up the economic status of these countries. These varieties are covering hundreds of millions of ha of agricultural land, whilst the impact on national economies of these countries is measured based on billions of dollars. The technique of mutation breeding is highly successful and its widespread implementation for crop improvement has led to the release of 3333 mutant varieties from 228 plant species (rice, wheat, and fruits like grapefruit, lettuce and others) in over 73 countries globally [56]. More than 1000 mutant varieties of major food crops covering millions of hectares, improving the rural economy, nutrition and helping in sustainable food security. Food insecurity is increasing worldwide and about 2 billion people especially in low and middle-income countries are undernourished. Concurrently, climatic changes also threatening the food supply chain on the global level, resulting in fast loss of biodiversity for food and agriculture. The ongoing unpredictable climatic changes are the core problem in reducing crop yields worldwide, thus continuous development of new improved varieties for sustainable production is unavoidable. While the rate of natural mutations in the crop plants is rare, thus use of induced mutation is indispensable to create genetic

**93**

during 2018.

**5. New breeding techniques (NBTs)**

techniques (**Figure 5**).

**Figure 5.**

*Potential of Mutation Breeding to Sustain Food Security DOI: http://dx.doi.org/10.5772/intechopen.94087*

diversity for the desired traits for use in the breeding programs. The widespread use of mutation techniques in plant breeding programs throughout the world has led to the official release of more than 3200 mutant varieties from more than 200 different plant species, in more than 70 countries. In Pakistan, more than 59 varieties of different crop species (wheat, rice, cotton, sugarcane, mungbean, lentil, sesame, castor bean, mandarin, rapeseed, mustard, chickpea and groundnut) have been released through the use of mutation breeding (chemical and physical)

*Mutant varieties released in Pakistan. Data source: MVD/IAEA. Accessed on 13th September, 2020.*

In China, only three mutant varieties are covering over 30 million ha and earn

New breeding techniques or NBTs are a list of seven plant breeding techniques for incorporating genetic diversity into crop plants using site-specific targeted mutagenesis in the genome with greater accuracy and less off-targeted mutations [57]. The use of these NBT mutations is described as precision breeding. These

US\$ 4.9 billion US dollars to uplift socio-economic status. In India, they have developed a huge number of mutant varieties and getting a large amount in return. In Bangladesh, Mutant rice varieties can be harvested a month earlier than the other varieties of rice-producing almost the same yield with superior quality. This variety is planted in three crop rotations and about 10,000 farmers cultivate this variety that is covering almost 80% of the area under rice cultivation. However, in Indonesia, an approximate amount of US\$ 2 billion has been received from a single top rice variety. Many farmers' and millions of citizens getting benefits from the mutant varieties released by Indonesia. In Peru, improved barley and amaranth mutant varieties helping farmers to earn 7 million Andean and providing food and economic benefits thus improving their life status. In Vietnam, mutant varieties of rice and soybean helping poor farmers to improve their livelihood and a top rive mutant cultivar earning US\$ 3.3 billion with an increase of US\$ 537.6 million over old varieties. Whilst soybean mutant varieties bring about US\$ 3 billion with 3.5 million farmers get a 30% increase in the economy. In Pakistan, 43 mutant varieties developed by NIAB showed an economic impact with earnings of US dollars 6 billion

*Potential of Mutation Breeding to Sustain Food Security DOI: http://dx.doi.org/10.5772/intechopen.94087*

#### **Figure 5.**

*Genetic Variation*

**3.3 Chemical mutagenesis**

potyvirus resistance in tomato [23].

**4. Mutant crop varieties and their impact on food security**

while China is using low-energy Ion bean to create improved crop varieties. The initial plant varieties produced using Ion bean mutagenesis included carnation (*Dianthus caryophyllus*), Chrysanthemum (*Dendranthema Grandiflora*), and plants of Verbena sp. Afterward, several color and shape variations of petunia, Dahlia, and Torenia were also developed using this mutagenesis technique. Furthermore, the varieties developed using Ion beam mutagenesis include not only ornamental plants of high commercial demand [46], but also crops like salt-tolerant rice, citrus fruits, coniferous trees, mutant blast-resistant rice [47], mutant muskmelon, and

Chemical mutagenesis is the most efficient and expedient tool used for a large number of plant species. Ethyl methane sulfonate and sodium azide are the most widely used chemical mutagens to induce mutations in various crop plants like a tomato. The chemical mutagens used in mutation breeding are ethyl methanesulphonate (EMS), hydroxylamine, methyl methanesulphonate (MMS), sodium azide hydrogen fluoride (HF), and N-methyl-N-nitrosourea (MNU) [32]. Although, EMS is the most extensively used mutagen in plants due to its high efficiency at inducing point mutation (changes in a single nucleotide) and deletions (loss of chromosomal segment) in the chromosomal fragments. Mutant populations in various cereal crops using chemical mutagens for seeds or pollens have been developed comprising maize [49], barley [50, 51], rice [52], sorghum [53], and both hexaploid bread wheat [54] and durum wheat [55]. The EMS was exploited for

Mutation breeding techniques especially gamma and other physical mutagens have helped in generating a large number of mutants and generated a massive quantity of genetic variability that is significantly employed in the studies from plant breeding and genetics and in modern studies (genomics) (**Figure 4**). The mutants are released directly as varieties or furnish as a basic resource in the breeding programs to create genetic variation. The released mutant varieties offer higher yields, disease-resistant, improved quality, and resilient to environmental swings. A huge number of these mutant cultivars have been released in developing regions boosting up the economic status of these countries. These varieties are covering hundreds of millions of ha of agricultural land, whilst the impact on national economies of these countries is measured based on billions of dollars. The technique of mutation breeding is highly successful and its widespread implementation for crop improvement has led to the release of 3333 mutant varieties from 228 plant species (rice, wheat, and fruits like grapefruit, lettuce and others) in over 73 countries globally [56]. More than 1000 mutant varieties of major food crops covering millions of hectares, improving the rural economy, nutrition and helping in sustainable food security. Food insecurity is increasing worldwide and about 2 billion people especially in low and middle-income countries are undernourished. Concurrently, climatic changes also threatening the food supply chain on the global level, resulting in fast loss of biodiversity for food and agriculture. The ongoing unpredictable climatic changes are the core problem in reducing crop yields worldwide, thus continuous development of new improved varieties for sustainable production is unavoidable. While the rate of natural mutations in the crop plants is rare, thus use of induced mutation is indispensable to create genetic

rice varieties with lower fertilizer requirements [48].

**92**

*Mutant varieties released in Pakistan. Data source: MVD/IAEA. Accessed on 13th September, 2020.*

diversity for the desired traits for use in the breeding programs. The widespread use of mutation techniques in plant breeding programs throughout the world has led to the official release of more than 3200 mutant varieties from more than 200 different plant species, in more than 70 countries. In Pakistan, more than 59 varieties of different crop species (wheat, rice, cotton, sugarcane, mungbean, lentil, sesame, castor bean, mandarin, rapeseed, mustard, chickpea and groundnut) have been released through the use of mutation breeding (chemical and physical) techniques (**Figure 5**).

In China, only three mutant varieties are covering over 30 million ha and earn US\$ 4.9 billion US dollars to uplift socio-economic status. In India, they have developed a huge number of mutant varieties and getting a large amount in return. In Bangladesh, Mutant rice varieties can be harvested a month earlier than the other varieties of rice-producing almost the same yield with superior quality. This variety is planted in three crop rotations and about 10,000 farmers cultivate this variety that is covering almost 80% of the area under rice cultivation. However, in Indonesia, an approximate amount of US\$ 2 billion has been received from a single top rice variety. Many farmers' and millions of citizens getting benefits from the mutant varieties released by Indonesia. In Peru, improved barley and amaranth mutant varieties helping farmers to earn 7 million Andean and providing food and economic benefits thus improving their life status. In Vietnam, mutant varieties of rice and soybean helping poor farmers to improve their livelihood and a top rive mutant cultivar earning US\$ 3.3 billion with an increase of US\$ 537.6 million over old varieties. Whilst soybean mutant varieties bring about US\$ 3 billion with 3.5 million farmers get a 30% increase in the economy. In Pakistan, 43 mutant varieties developed by NIAB showed an economic impact with earnings of US dollars 6 billion during 2018.

### **5. New breeding techniques (NBTs)**

New breeding techniques or NBTs are a list of seven plant breeding techniques for incorporating genetic diversity into crop plants using site-specific targeted mutagenesis in the genome with greater accuracy and less off-targeted mutations [57]. The use of these NBT mutations is described as precision breeding. These

techniques are zinc finger nuclease (ZFN) technology, oligonucleotide-directed mutagenesis (ODM), cisgenesis and intragenesis, grafting on GM-rootstock, RNAdependent DNA methylation, agro-infiltration "sensustricto," and reverse breeding. The ZFN tool one of the site-directed nuclease (SDN) can be implemented to create a site-specific mutation in the plant genome. In addition, a number of new SDN techniques have been introduced viz. TALEN and CRISPR/Cas, and the latter is now extensively being used [57]. Recently, IAEA and FAO jointly launched a program known as Plant Mutation Breeding Network (PMBN) on the basis of a large number of crop varieties (2000) in the Asia Pacific region [58]. Out of these, 826 rice varieties to date have been released using mutation breeding, of these 699 were from the Asia-pacific region, with 290 from china. This program will be beneficial to farmers and researchers by developing new improved varieties with a higher yield, stability, and quality traits, disease resistance and resilience to changing climates through mutagenesis. The PMBN will work to further expand these great achievements jointly among the member countries. The conjoint use of classical mutation breeding method through screening of TILLING populations NBT mutations can be employed implicitly in the modification of plant attributes. The main advantage of NBT over the classical mutation technique is its precision and specificity that could be utilized to find robust mutation sites without the unwanted genetic changes that are the main problem in the classical mutation breeding. Resultantly, desired mutations could be retrieved through traditional mutation techniques. This is a lengthy process but of high applicability because of efficient tools to create mutant populations and to screen these mutations for targeted genes [59].

#### **6. Prospects**

With the rising food demands, the development of new crop varieties with improved yield potential and better resistance to biotic and abiotic stresses is vital. Modern techniques, molecular, and omics are the tools in hand to speed up the breeding route in integration with conventional (mutation/hybridization) methods. The integrated approach of using genomic and omics data with genetic and phenotypic data helps to unfold the genes/pathways connected with desired traits [60]. The conventional breeding methods have been employed extensively in combination with transformation, gene editing and marker-assisted selection (MAS). The selection of suitable parental materials endowed with desired traits in different crop species is fundamental for any successful breeding program. The highly favored markers known as Single Nucleotide Polymorphisms (SNPs) are helpful to analyze genetic variability and population configuration, in constructing genetic maps and to present genotypes for GWAS (genome-wide association analysis) [61]. Singlenucleotide polymorphisms (SNPs) are markers of choice to detect genetic diversity in crop plants [62]. Genotyping by sequencing (GBS) technique is based on nextgeneration-sequencing also done with SNP markers to incorporate high throughput genotyping [63]. These molecular techniques in combination with NBTs can do a miraculous job in the future to develop environment resilient cultivars to help fighting food security.

#### **7. Conclusions**

Mutation breeding has substantially contributed to crop improvements worldwide. Thousands of mutant crop varieties released in different countries

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**Author details**

**Conflict of interest**

Arain Saima Mir1

Islamabad, Pakistan

\*, Meer Maria2

provided the original work is properly cited.

\*Address all correspondence to: saimamir\_nia@yahoo.com

, Sajjad Muhammad<sup>2</sup>

1 Nuclear Institute of Agriculture (NIA), Tando Jam, PO Box 70060, Pakistan

2 Department of Biosciences, COMSATS University Islamabad (CUI), Park Road,

© 2020 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,

and Sial Mahboob Ali1

*Potential of Mutation Breeding to Sustain Food Security DOI: http://dx.doi.org/10.5772/intechopen.94087*

The authors declare no conflict of interest.

have significantly improved yield potential, nutritional quality, biotic and abiotic stress tolerance. Several mutants with one or few desirable traits in different crops or vegetables are widely used as parents for breeding new commercial cultivars. Besides developing thousands of crop varieties, mutation breeding has created tremendous genetic resources for all major crops and vegetables worldwide. The integration of the latest mutation breeding tools with robust selection and speed breeding tools increases its scope in meeting food security challenges with expo-

nentially increasing human population and climate change scenarios.

*Potential of Mutation Breeding to Sustain Food Security DOI: http://dx.doi.org/10.5772/intechopen.94087*

have significantly improved yield potential, nutritional quality, biotic and abiotic stress tolerance. Several mutants with one or few desirable traits in different crops or vegetables are widely used as parents for breeding new commercial cultivars. Besides developing thousands of crop varieties, mutation breeding has created tremendous genetic resources for all major crops and vegetables worldwide. The integration of the latest mutation breeding tools with robust selection and speed breeding tools increases its scope in meeting food security challenges with exponentially increasing human population and climate change scenarios.
