Wheat chromosome instability in the selfed progeny of the double monosomics 1Rv-1A

Abstract

Structural alterations of chromosomes are often found in wheat-rye hybrids. In the majority of cases modifications are observed for rye chromosomes, yet chromosome aberration cases are described for wheat, including the progeny of Triticum aestivum disomic and monosomic addition lines. Since wheat-rye substitution and translocation lines are the source of rye chromatin in wheat breeding programs, information on possible chromosome changes in the genomes of introgressive forms is important. Chromosome behavior in F 1 meiosis and chromosomal composition of F 2 karyotypes for double monosomics 1Rv-1A were studied by applying С-banding, genomic in situ hybridization (GISH) using rye genomic DNA, and sequential in situ hybridization using repetitive sequences pAs1, pSc119.2 and centromere specific pAet-06 as probes. The double monosomics 1Rv-1A were obtained by crossing of disomic substitution line with chromosome 1А replaced by Secale сereale 1Rv in the bread wheat Saratovskaya 29 (S29) background with S29. The results indicated a high frequency of bipolar chromosome 1Rv orientation, as compared to 1А, at metaphase I (MI) (58.6 and 34.7 % of meiocytes, respectively), and, at anaphase I (AI), chromatid segregation of 1Rv compared to 1A (70.53 and 32.14 % of meiocytes, respectively). In few cases desynapsis of wheat homologues was observed, at AI, the chromosomes randomly distributed between the poles or underwent chromatid segregation. At АI, the two wheat homologues separated onto sister chromatids in 10.89 % of cells. The plant F 2 karyotypes were marked with aneuploidy not only of chromosomes 1A and 1Rv, but also of 1D,

Asynapsis and unreduced gamete formation in a Trifolium interspecific hybrid

“…If the cohesion is removed early, at the transition of metaphase I to anaphase I, univalents display premature separation of sister chromatids and undergo equational division [ 28 , 33 , 44 ]. Alternatively, if the removal of cohesion is incomplete or the removal continues during anaphase I, the spindle collapses due to opposing forces between the spindle microtubules and the remnant kinetochore cohesion, laggards occur, and an unreduced restitution nucleus is generated [ 28 , 29 , 44 , 45 ].…”

“…The simultaneous equational division of univalents and reductional division of bivalents and multivalents on the same spindle, as observed in this and other studies, can thus be understood. As noted earlier, variability in the dissolution of centromeric cohesion in univalents during meiosis I may lead to segregational failure [ 44 , 45 ]. Several studies in the Triticeae and in grasshoppers have shown that the greater the number of univalents, the greater the chance of spindle collapse leading to meiotic restitution and unreduced gametes [ 29 , 34 , 44 ].…”

The creation and characterization of the bread wheat line with a centric translocation T2DL.2RL

“…Флуоресцентная in situ гибридизация (FISH). Митотические и мейотические препараты для FISH готовили по описанной ранее методике (Silkova et al, 2018). Митотические препараты готовили из корешков вегетирующих растений BC 3 F 1 .…”

“…Работы по передаче чужеродного генетического материала в геном пшеницы не теряют своей актуальности, формы пшеницы с новыми ценными признаками создаются во многих лабораториях мира, а потенциал генофонда ржи как источник хозяйственно ценных признаков далеко не исчерпан (An et al, 2013;Ren et al, 2017;Schlegel, 2019). В качестве источника важных признаков используются линии с пшенично-ржаным замещением хромосом 2R(2D) 1 и центрическими транслокациями, в структуру которых включено длинное плечо хромосомы ржи 2RL.…”