Strategies for the utilization of USDA mungbean germplasm collection for breeding outcomes

Global and mid-west U.S. agriculture requires diversification and new
sources of protein for sustainable crop production. Mungbean as a legume
crop has a long cultivation history in Asia; however, its potential lays
hitherto underexplored in the U.S. As a first step towards exploring
mungbean for crop diversification in northern latitudes, crop germplasm
centers that harbor worldwide crop resources need to be utilized. This
study explores the potential of mungbean in the U.S. northern latitudes
through the utilization of the United States Department of Agriculture
(USDA) germplasm resources. Complete collection of USDA mungbean germplasm
was screened under Iowa field conditions in 2017, to shortlist 482
accessions to create an Iowa mungbean panel. The Iowa mungbean panel was
further characterized for field adaptability traits in 2018 and 2019 and
genotyped using genotype-by-sequencing (GBS) to conduct association
mapping of important traits. Genetic markers were identified for both
quantitative traits - days to flowering (DTF), plant height (PHT),
leaf-drop at maturity (LDMS), 100-seed weight (SDWT) and Fusarium wilt
score (WS), and qualitative traits; seed color (SC), seed-coat texture
(ST), hypocotyl color (HC), and pod-color (PC). We report FERONIA, a known
flowering-pathway gene as the candidate gene for the QTL with largest
effect on DTF. In addition, important epistatic interactions were also
uncovered for WS and SDWT. Further, accessions with desirable magnitude of
traits were identified as potential parents. Diversity analyses and field
phenotypic data indicates potential for mungbean improvement to suit
mid-western U.S. cultivation.