Molecular cytogenetic identification of three rust-resistant wheat- Thinopyrum ponticum partial amphiploids.

Background: Thinopyrum ponticum (2n = 10× = 70, JS JS JS JS JJJJJJ) is an important wild perennial Triticeae species that has a unique gene pool with many desirable traits for common wheat. The partial amphiploids derived from wheat- Th. ponticum set up a bridge for transferring valuable genes from Th. ponticum into common wheat.

Results: In this study, genomic in situ hybridization (GISH), multicolor GISH (mcGISH) and fluorescence in situ hybridization (FISH) were used to analyze the genomic constitution of SN0389, SN0398 and SN0406, three octoploid accessions with good resistance to rust. The results demonstrated that the three octoploids possessed 42 wheat chromosomes, while SN0389 contained 12 Th. ponticum chromosomes and SN0398 and SN0406 contained 14 Th. ponticum chromosomes. The genomic constitution of SN0389 was 42 W + 12JS , and for SN0398 and SN0406 it was 42 W + 12JS  + 2 J. Chromosomal variation was found in chromosomes 1A, 3A, 6A, 2B, 5B, 6B, 7B, 1D and 5D of SN0389, SN0398 and SN0406 based on the FISH and McGISH pattern. A resistance evaluation showed that SN0389, SN0398 and SN0406 possessed good resistance to stripe and leaf rust at the seedling stage and adult-plant stage.

Conclusions: The results indicated that these wheat- Th. ponticum partial amphiploids are new resistant germplasms for wheat improvement.