Phenotypic Variation and Patterns of Linkage Disequilibrium Associated with Introduced Genes in Spring Wheat

Abstract

ABSTRACTIntroduction of genes from outside a primary germplasm base has the potential to impact phenotypic diversity, genetic structure, and patterns of linkage disequilibrium (LD). Our goals were to monitor the introduction of key genes in a hard red spring wheat (Triticum aestivum L.) germplasm set using historical cultivars, to determine the impact of the introduced genes on phenotypic diversity in elite germplasm, and to assess the impact of selection history on LD. A superior allele for bread making was introduced early in the 20th century and quickly became fixed. An allele for solid stems introduced in the mid 20th century is the major source of variation in current germplasm. An introduced allele for photoperiod insensitivity is an important source of variation for heading date in current germplasm. The allelic introductions impacted patterns of LD. The unlinked loci for reduced height, RHT‐B1 and RHT‐D1, were in LD. Linkage disequilibrium for physically linked markers near introduced genes did not exceed previous estimates of genome‐wide LD. Our results showed a pattern of gene introductions into the spring wheat germplasm base that continues to have an impact on phenotypic diversity and patterns of LD.