Genetic Composition Analysis of a New Multi-Resistant and High-Yield Wheat Variety, Chuanmai 82

Chuanmai 82 is a new multiple disease-resistant and high-yielding wheat variety bred from the durable disease-resistant germplasm Singh6, developed by the International Maize and Wheat Improvement Center (CIMMYT). This study aimed to construct a high-density genotypic map of Chuanmai 82, quantify the genomic contribution rates of its two parental lines, analyze its genetic composition, and clarify the parental origins of genetic loci associated with key traits such as disease resistance and yield. The findings provide a scientific basis for wheat variety improvement and the precise selection of parental lines in breeding programs.

The wheat 100K SNP array was used to perform whole-genome scanning of Chuanmai 82 and its two parents. This enabled a systematic analysis of its genetic architecture. Combined with the functional markers related to important agronomic traits and yield traits carried on the SNP array, the allelic genotype of Chuanmai 82 was analyzed to trace the genetic sources of its disease resistance and yield-related traits.

Whole-genome analysis indicated that the genetic contributions of the donor parent Singh6 and the recurrent parent Chuanong 16 to Chuanmai 82 were 16.36% and 83.64%, respectively, which aligns with the theoretical expectations of backcross breeding. The contribution rates exhibited a gradient difference across the subgenomes A, B, and D, with A>B>D. At the chromosomal level, the genetic fragments from Singh6 were not uniformly distributed, contributing 49.24% to 86.91% of the genetic components on chromosomes 1B, 2D, 4B, 5D, and 6A, forming significant large-segment donor regions. In contrast, Chuanong 16 contributed over 89% to most of the remaining chromosomes, constituting the genetic background of the variety. Functional marker-based tracing further demonstrated that the stripe rust, leaf rust, and powdery mildew resistance genes in Chuanmai 82 were predominantly derived from Singh6, while the pre-harvest sprouting resistance and yield-related genes were mainly inherited from Chuanong 16.

This study accurately quantified the genetic composition of Chuanmai 82 at both the genome and chromosome levels. Notably, the genetic contribution of the donor parent Singh6 was concentrated on chromosomes 1B, 2D, 4B, 5D, and 6A, forming large-segment donor regions that retained the genetic diversity of the donor parent. Combined with functional marker analysis, some of these regions were enriched with rust and powdery mildew resistance genes from Singh6. Therefore, the optimal combination of these large-segment donor regions (carrying disease resistance genes) and the high-yield genetic background from Chuanong 16 is likely the key genetic basis for the synergistic enhancement of durable disease resistance and high yield in Chuanmai 82.