**Cytogenetic Collection of Uzbekistan**

Marina Sanamyan, Julia Petlyakova, Emma Rakhmatullina and Elnora Sharipova

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/58589

## **1. Introduction**

[63] Zhang, J.F., Y. Liu, R.G. Cantrell, and E. Hughs. 2005b. Molecular marker diversity and field performance in commercial cotton cultivars evaluated in the southwestern

[64] Zhong, M., J.C. McCarty, J.N. Jenkins, and S. Saha. 2002. Assessment of day-neutral backcross populations of cotton using AFLP markers. J. Cotton Sci. 6:97-103.

USA. Crop Sci. 45:1483-1490.

246 World Cotton Germplasm Resources

The genetic improvement of cotton demands the use of cytogenetic stocks for molecular mapping of QTLs and introgression of beneficaila genes from wild and unadapted germplasms in Upland cotton. Development of the collection of cotton cytogenetic lines with translocations and chromosome deficiencies are necessary to fulfill these goals. During long-term studies the series of translocations and monosome stocks were developed in the USA, which provide chromosome identification and localization of marker genes on chromosomes. As the result, totally, 63 translocations were accumulated over a period of more than 20 years in USA [1-2]. The 62 heterozygous translocations were transferred to homozygous state and identified. Twenty reciprocal translocations of the cytogenetic tester set of *G. hirsutum* were selected and cytologically characterized [3,4]. This tester set of the translocations marks 25 of the 26 chromosomes of *G. hirsutum*, with chromosome 26 being identified by elimination.

Cultivated allotetraploid cotton, *G. hirsutum* (2n=52), is tolerant to the loss of individual chromosomes or their arms. During long-term investigations a big number of monosomic plants of different origin were isolated in the USA [5-9]. The majority of monosomes were found for chromosomes 2, 4 and 6 of the A-genome [10]. Unfortunately, the complete series of 26 monosomic lines in cotton have not been recovered yet. The monosomes for 15 of the 26 nonhomological chromosomes of *G. hirsutum* were identified [2]. Therefore the development of one or more deficiencies which would involve a part and/or all of these chromosomes has been high priority [11]. Use of the new molecular cytogenetic methods – meiotic fluorescence in situ hybridization (FISH) was identifed a new cotton monosome of chromosome 23 [12]. Recently, another new monosome for chromosome 21 in cotton was reported [13]. During the last years the monosomic stocks were used for chromosome assignment genetic and molecular markers to specific chromosomes [14-21].

© 2014 The Author(s). Licensee InTech. 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.

Use of F1 hypoaneuploid hybrids resulting from the crosses of *G. hirsutum* aneuploids (2n-1 or 2n-1/2) and *G. barbadense* L. species (2n) in molecular-genetic analyses has facilitated the localization of different molecular markers on specific cotton chromosomes [22-25]. However, some loci were not assigned using the aneuploids due to the lack of a full set of cotton aneuploids [e.g. 21, 25-27]. In the last decade chromosome-deficient stocks of *G. hirsutum* have been used for the development of chromosome substitution lines for *G. barbadense, G. tomen‐ tosum* and *G. mustelinum* chromosomes or chromosomes segment(s) [28-29].

rays (A) of the seeds, irradiation of seeds by thermal neutrons (B) and pollen gamma irradiation rays (C). The seeds of the hybrids F0 (L-500 x L-461) were treated with 0.1% aqueous colchicines solution for 2 h, washed with water and irradiated with CO60 gamma-radiation at 50 and 100

Cytogenetic Collection of Uzbekistan http://dx.doi.org/10.5772/58589 249

The irradiation of pollen by gamma rays was carried out in Institute of Silk research. The flowers of cotton line L-458 were emasculated a day before flowering and enclosed in parch‐ ment bags to prevent accidental crosspollination and in flowering stage the flowers with mature pollen were collected and irradiated with 10, 15, 20 and 25 Gy gamma radiation (Co60).

The neutron irradiation of cotton line L-458 seeds was carried out at the biological channel of the WW-SM reactor using doses of 15, 25, 27 and 35 Gy (Institute of Nuclear Physics of the Academy Sciences of the Republik of Uzbekistan, Tashkent). The seeds of M0 generation were grown in same field condition. The M1 plants were studied and used to raised the M2 genera‐ tion. The M2 plants were grown in a field and investigated for chromosomal aberrations using

The primary monosomics from our collection were numbered from Mo1 to Mo94 in the order of their detection. Transmission of the monosomics was studied in selfing and outcrossing progenies of monosomic plants both in the greenhouse and in the field. Translocation and monosomic lines were identified. Hybrids between translocation and monosomic lines were analyzed to identify 2n and 2n-1 translocation heterozygotes, respectively. Meiotic chromo‐

The chromosome pairing at metaphase I of meiosis was studied. The calyx and corolla were removed and floral buds were fixed overnight in 96% alcohol and acetic acid (7:3). Buds were kept at room temperature for 3 days, immersed in fresh fixative and stored in a refrigerator. They were examined for meiotic associations in the pollen mother cells (PMCs) using iron acetocarmine squash technique [30]. The analysis of chromosomal changes was carried out on the basis of M I associations at the first meiosis. The development of PMCs was examined at the tetrad stage for each plant. The meiotic index was calculated as the percentage of tetrads

Reciprocal translocations were formed as segmental interchanges among two or more nonhomologous chromosomes. The exposure of seeds to three types of irradiation has resulted in the induction of translocations in 235 cotton plants [31, 32, 34, 37]. After different treatment

somes were studied using the standard acetocarmine-squash technique [30].

whereas pollen fertility was estimated by acetocarmine staining.

Gy. The seeds used in this study were of the M0 generation.

The irradiated pollen used to pollinate the emasculated flowers.

cytological techniques.

**3. Cytological analysis**

**4.1. Reciprocal translocations**

**4. Results**

In Uzbekistan the investigations to induce chromosome aberrations and to develop new translocation and chromosome deficient stocks were conducted during more than 30 years [30-43]. As the result 94 primary and 22 tertiary monosomics, 20 monotelodisomics, 4 mono‐ isodisomics, 235 reciprocal translocations as heterozygotes, 33 homozygous translocation stocks, 4 haploids and 31 desynaptic plants were discovered (Table 1). Here we report cytogenetic and morphological characteristics of the new cotton translocation and monosomic lines. We also report the results of identification of some of the lines by means translocation test.


**Table 1.** The origin of the different aberrations in cotton *G.hirsutum* L.

## **2. Materials and methods**

Inbred cotton lines L-458, L-461, L-500 and L-501 (*Gossypium hirsutum L.)* from the Genetic Collection of the National University of Uzbekistan were used for producing cytogenetic stock series. Three types of radiations were applied – combined treatment of colchicine and gamma rays (A) of the seeds, irradiation of seeds by thermal neutrons (B) and pollen gamma irradiation rays (C). The seeds of the hybrids F0 (L-500 x L-461) were treated with 0.1% aqueous colchicines solution for 2 h, washed with water and irradiated with CO60 gamma-radiation at 50 and 100 Gy. The seeds used in this study were of the M0 generation.

The irradiation of pollen by gamma rays was carried out in Institute of Silk research. The flowers of cotton line L-458 were emasculated a day before flowering and enclosed in parch‐ ment bags to prevent accidental crosspollination and in flowering stage the flowers with mature pollen were collected and irradiated with 10, 15, 20 and 25 Gy gamma radiation (Co60). The irradiated pollen used to pollinate the emasculated flowers.

The neutron irradiation of cotton line L-458 seeds was carried out at the biological channel of the WW-SM reactor using doses of 15, 25, 27 and 35 Gy (Institute of Nuclear Physics of the Academy Sciences of the Republik of Uzbekistan, Tashkent). The seeds of M0 generation were grown in same field condition. The M1 plants were studied and used to raised the M2 genera‐ tion. The M2 plants were grown in a field and investigated for chromosomal aberrations using cytological techniques.

The primary monosomics from our collection were numbered from Mo1 to Mo94 in the order of their detection. Transmission of the monosomics was studied in selfing and outcrossing progenies of monosomic plants both in the greenhouse and in the field. Translocation and monosomic lines were identified. Hybrids between translocation and monosomic lines were analyzed to identify 2n and 2n-1 translocation heterozygotes, respectively. Meiotic chromo‐ somes were studied using the standard acetocarmine-squash technique [30].
