Cytogenetic analysis of translocations in cotton

Abstract

In order to create cotton translocation lines, 191 translocations were recovered as heterozygotes following combined treatment of seeds by colchicine and c-rays, irradiation of seeds by thermal neutrons and c-irradiation of pollen. Cytogenetic analysis showed that chromosome translocations involving two chromosomes arose more often (180) than those involving three chromosomes (11). The heterozygous translocations were characterized by different formation and frequencies of the multivalents at metaphase I of meiosis. Only 104 translocations were characterized by a multivalent frequency of more than 0.25 per cell. Most of the translocations (156) exhibited a high meiotic index, but 11 were characterized by a decreasing meiotic index and by an increase in the percentage of tetrads with micronuclei. The pollen fertility of translocations differed significantly and varied from high fertility to pollen sterility. The high frequency of abortive pollen grains was typical for about one half of translocations studied. The translocations were made homozygous and as a result, 12 new reciprocal homozygous translocation lines were obtained in cotton.

Morphological characteristics and identification of new monosomic stocks for cotton (Gossypium hirsutum L.)

“…During the past several decades, we extensively worked on the development of aneuploid cotton lines from common genetic background of highly inbred line L-458 of G. hirsutum using radioactive irradiation techniques that resulted in creation of novel sets of monosomic and translocation lines for cotton. The preliminary cytogenetic and morphological characteristics of this new collection were partially reported previously [15][16][17][18][19][20][21]. Cytogenetic details of this new monosomic collection are also studied (Sanamyan et al 2010, unpublished, submitted for publication elsewhere).…”

“…Identification of the monosomes was carried out using the translocation test. For this purpose, the homozygous translocation lines from Uzbek Cytogenetic Collection [17][18][19] were crossed with the monosomics as males.…”

“…Analysis of hybrid chromosome pairing was used to reveal monosomic translocation F 1 hybrids and to study "critical configurations". The recently developed 28 translocation lines (Tr1-Tr28) from our collection [17,18] were used for monosome identification according to the method described previously [29]. Our initial efforts to monosome identification were presented in previous article [16].…”

Cytogenetic Collection of Uzbekistan

“…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][31][32][33][34][35][36][37][38][39][40][41][42][43]. As the result 94 primary and 22 tertiary monosomics, 20 monotelodisomics, 4 monoisodisomics, 235 reciprocal translocations as heterozygotes, 33 homozygous translocation stocks, 4 haploids and 31 desynaptic plants were discovered (Table 1).…”

Cytogenetic Characteristics of New Monosomic Stocks of Cotton (Gossypium hirsutumL.)

“…In Uzbekistan, independent investigations on creation of cytogenetic lines in G. hirsutum using numerous chromosome aberrant radiomutant plants have been carried out [13–15]. As a result, unlike other multiple-genotype-derived cytogenetic collections for cotton, a new set of monosomic and translocation lines have been developed from the common genetic background of the highly inbred line L-458 ( G. hirsutum ).…”