Xie Q, Kang H, Sparkes D L, Tao S, Fan X M, Xu L, Fan X, Sha L, Zhang H, Wang Y, Zeng J, Zhou Y
Triticeae Research Institute, Sichuan Agricultural University, Wenjiang, Chengdu, Sichuan, China.
Genet Mol Res. 2013 Jul 24;12(3):2537-48. doi: 10.4238/2013.January.4.16.
The dynamics of rye chromosomes during mitosis and meiosis was analyzed in a subset comprising 33 F3 lines from the cross of wheat, Psathyrostachys huashanica amphiploid (AABBDDNsNs) and hexaploid triticale (AABBRR), as visualized by genomic in situ hybridization. The results indicated that 31 of the total lines contained 4-14 rye chromosomes. Twenty-eight combinations had more rye chromosomes than the F1 hybrids, suggesting the occurrence of spontaneous quantitative increment. No P. huashanica chromosomes were detected in all of the combinations tested. Mitotic analysis showed that rye chromosomes progressed normally with the wheat counterparts without loss. However, abnormal meiosis was found in almost all lines. Similar progression between wheat and rye genomes appeared from interphase to metaphase I. It was at anaphase I that many rye univalents lagged behind those of wheat, followed by equational division. This resulted in the formation of chromosomal segments and micronuclei at telophase I or II. Micronuclei could also be generated from the immobilized univalents in the periphery of cells. Synapsis and translocations between wheat and rye genomes, chromosome bridges, and unreduced gametes were detected. Therefore, it is proposed that rye chromosome elimination may involve chromatid lagging, fragmentation and micronucleation, or the immobilization of certain univalents during meiosis instead of mitosis in the relatively advanced generations. This mechanism, together with spontaneous incremental increase of rye chromosome number, permitted the generation of various germplasms for wheat improvement.
通过基因组原位杂交技术，对小麦、华山新麦草双二倍体（AABBDDNsNs）与六倍体小黑麦（AABBRR）杂交后代的33个F3株系进行分析，研究了黑麦染色体在有丝分裂和减数分裂过程中的动态变化。结果表明，33个株系中有31个含有4-14条黑麦染色体。28个组合中的黑麦染色体数目多于F1杂种，表明发生了自发的数量增加。在所有测试组合中均未检测到华山新麦草染色体。有丝分裂分析表明，黑麦染色体与小麦染色体正常同步，没有丢失。然而，几乎所有株系都发现了减数分裂异常。从间期到中期I，小麦和黑麦基因组之间的进程相似。在后期I，许多黑麦单价体落后于小麦单价体，随后进行均等分裂。这导致在末期I或II形成染色体片段和微核。微核也可能由细胞周边固定的单价体产生。检测到小麦和黑麦基因组之间的联会和易位、染色体桥和不减数配子。因此，有人提出，在相对较高级别的世代中，黑麦染色体消除可能涉及染色单体滞后、断裂和微核化，或减数分裂过程中某些单价体的固定，而不是有丝分裂。这种机制，连同黑麦染色体数目的自发增加，为小麦改良提供了各种种质。
