Chromosome diversity in Dasypyrum villosum, an important genetic and trait resource for hexaploid wheat engineering.Ann Bot. 2022 Apr 22 [Online ahead of print]AB
BACKGROUND AND AIMS
Dasypyrum villosum (2n = 2x = 14) harbors potentially beneficial genes for hexaploid and tetraploid wheat improvement. Highly diversified chromosome variation exists among and within accessions due to its open-pollination nature. The wheat-D. villosum T6VS·6AL translocation was widely used in breeding mainly because gene Pm21 in the 6VS segment conferred high and lasting powdery mildew resistance. However, the widespread use of this translocation may narrow genetic base of wheat. A better solution for this issue is to utilize diversified D. villosum accessions as genetic source for wheat breeding. Analysis of cytological and genetic polymorphisms among D. villosum accessions also provides genetic evolution information of the species. Using cytogenetic and molecular tools we analyzed genetic polymorphisms among D. villosum accessions and developed consensus karyotypes to assist the introgression of beneficial genes from D. villosum into wheat.
A multiplex probe of repeats for FISH, GISH and molecular markers were used to detect chromosome polymorphisms among D. villosum accessions. The polymorphic signal block types, chromosome heterogeneity and heterozygosity, and chromosome polymorphic information content (CPIC) were used in genetic diversity analysis.
Consensus karyotypes of D. villosum were developed, and the homoeologous status of individual D. villosum chromosomes relative to wheat were determined. The tandem repeat probes of pSc119.2, (GAA)10 and AFA family produced high-resolution signals not only showing different signal patterns in D. villosum chromosomes but also revealed the varied distribution of tandem repeats among chromosomes and accessions. A total of 106 polymorphic chromosomes were identified from 13 D. villosum accessions and high levels of chromosomal heterozygosity and heterogeneity were observed. A subset of 56 polymorphic chromosomes was transferred into durum wheat through wide crosses, and seven polymorphic chromosomes are described in two newly developed durum-D. villosum amphidiploids.
Consensus karyotypes of D. villosum and oligonucleotide FISH facilitated identification of polymorphic signal blocks and a high level of chromosomal heterozygosity and heterogeneity among D. villosum accessions, seen in newly developed amphiploids. The abundant genetic diversity of D. villosum and range of alleles, exploitable through interploid crosses, backcrosses and recombination - chromosome engineering - allow introduction of biotic and abiotic stress resistances into wheat, translating into increasing yield, end-use quality and crop sustainability.