Investigation of chromosomal genetic characteristics and identification of structural variation in the offspring of hexaploid triticale×hexaploid wheat.

Abstract

Hexaploid triticale is an important genetic resource for genetic improvement of common wheat, which can broaden the genetic basis of wheat. In order to lay a foundation for the subsequent research and utilization of triticale germplasm materials, the chromosomal genetic characteristics of cross and backcross offspring of hexaploid triticale×hexaploid wheat were investigated in the process of transferring rye chromatin from hexaploid triticale to hexaploid wheat. Hybrid and backcross combinations were prepared with hexaploid triticale 16yin171 as the maternal parent and hexaploid wheat Chuanmai62 as the paternal parent. The chromosomes in root tip cells of F₁, BC₁F₁ and BC₁F₂ plants were traced and identified non-denaturing florescence in situ hybridization (ND-FISH). The results indicated that the backcross setting rate of hybrid F₁ was 2.61%. The transmission frequency of 2R chromosome was the highest in BC₁F₁ plants while the transmissibility of rye chromosome in BC₁F₂ plant was 6R>4R>2R, and the 5B-7B wheat translocation in BC₁F₂ plants showed severe segregation. A total of 24 structural variant chromosomes were observed both in BC₁F₁ and BC₁F₂ plants, including chromosome fragments, isochromosomes, translocations, and dicentric chromosomes. In addition, the seed length and 1000-grain weight of some BC₁F₂ plants were better than that of the hexaploid wheat parent Chuanmai 62. Therefore, multiple backcrosses should be adopted as far as possible to make the rapid recovery of group D chromosomes, ensuring the recovery of fertility in offspring, when hexaploid tritriale is used as a bridge to introduce rye genetic material into common wheat. At the same time, the potential application value of chromosomal structural variation materials should be also concerned.