Abstract
Pleiotropy is considered to have a significant impact on multi-trait evolution, but its roles in the evolution of domestication-related traits in crop species have been unclear. In soybean, several known quantitative trait loci (QTL) controlling maturity, called the maturity loci, are known to have major effects on both flowering and maturity in a highly correlated pleiotropic manner. Aiming at the identification of non-pleiotropic QTLs that independently control flowering and maturity and dissecting the effects of pleiotropy in these important agronomic traits, we conducted a QTL mapping experiment by creating a population from a cross between domesticated soybean G. max and its wild ancestor G. soja that underwent stringent selection for non-pleiotropy in flowering and maturity. Our QTL mapping analyses using the experimental population revealed novel loci that acted in a non-pleiotropic manner: R1-1 controlled primarily flowering and R8-1 and R8-2 controlled maturity, while R1-1 overlapped with QTL, affecting other agronomic traits. Our results suggest that pleiotropy in flowering and maturity can be genetically separated, while artificial selection during soybean domestication and diversification may have favored pleiotropic loci such as E loci that control both flowering and maturity. The non-pleiotropic loci identified in this study will help to identify valuable novel genes to optimize soybean’s life history traits and to improve soybean’s yield potential under diverse environments and cultivation schemes.
Highlights
Genetic pleiotropy, correlation among traits due to genes that possess pleiotropic roles or the linkage of multiple genes, is known to have a major impact on the multi-trait evolution of organisms.Neutral theories and evolutionary models suggest that pleiotropy is a cause of evolutionary constraints, preventing organisms from evolutionary progress [1,2]
Mimicking the domestication and diversification processes of soybean, two backcrosses to Williams 82 were performed after the initial cross between Williams 82 and PI 549046, and plants that showed agronomic appearance similar to Williams 82 in traits such as lodging, height, and stem vininess were selected through multiple generations
We focused on the key domestication-related traits flowering and maturity that were known to behave in a highly correlated manner in domesticated soybean
Summary
Correlation among traits due to genes that possess pleiotropic roles or the linkage of multiple genes, is known to have a major impact on the multi-trait evolution of organisms. Neutral theories and evolutionary models suggest that pleiotropy is a cause of evolutionary constraints, preventing organisms from evolutionary progress [1,2]. Crop domestication provides a unique opportunity to dissect the effects of pleiotropy on multi-trait evolution. Intense selection by humans during crop domestication and diversification processes causes rapid and directional changes in a set of traits, typically including non-seed shattering, reduced branching, apical dominance, Agronomy 2020, 10, 1204; doi:10.3390/agronomy10081204 www.mdpi.com/journal/agronomy. Much remains unknown about the extent of pleiotropy among domestication-related traits and its consequences in the evolution of crop species
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