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Mung bean [ Vigna radiata (L.) Wilczek] is a drought-tolerant, short-duration crop, and a rich source of protein and other valuable minerals, vitamins, and antioxidants. The main objectives of this research were (1) to study the root traits related with the phenotypic and genetic diversity of 375 mung bean genotypes of the Iowa (IA) diversity panel and (2) to conduct genome-wide association studies of root-related traits using the Automated Root Image Analysis (ARIA) software. We collected over 9,000 digital images at three-time points (days 12, 15, and 18 after germination). A broad sense heritability for days 15 (0.22–0.73) and 18 (0.23–0.87) was higher than that for day 12 (0.24–0.51). We also reported root ideotype classification, i.e., PI425425 (India), PI425045 (Philippines), PI425551 (Korea), PI264686 (Philippines), and PI425085 (Sri Lanka) that emerged as the top five in the topsoil foraging category, while PI425594 (unknown origin), PI425599 (Thailand), PI425610 (Afghanistan), PI425485 (India), and AVMU0201 (Taiwan) were top five in the drought-tolerant and nutrient uptake "steep, cheap, and deep" ideotype. We identified promising genotypes that can help diversify the gene pool of mung bean breeding stocks and will be useful for further field testing. Using association studies, we identified markers showing significant associations with the lateral root angle (LRA) on chromosomes 2, 6, 7, and 11, length distribution (LED) on chromosome 8, and total root length-growth rate (TRL_GR), volume (VOL), and total dry weight (TDW) on chromosomes 3 and 5. We discussed genes that are potential candidates from these regions. We reported beta-galactosidase 3 associated with the LRA, which has previously been implicated in the adventitious root development via transcriptomic studies in mung bean. Results from this work on the phenotypic characterization, root-based ideotype categories, and significant molecular markers associated with important traits will be useful for the marker-assisted selection and mung bean improvement through breeding. [ABSTRACT FROM AUTHOR]

Global and midwestern U.S. agriculture requires diversification and new sources of protein for sustainable crop production. Mung bean [Vigna radiata (L.) R. Wilczek] as a legume crop has a long cultivation history in Asia; however, its potential lays hitherto underexplored in the United States. As a first step towards exploring mung bean for crop diversification in northern latitudes, crop germplasm centers that harbor worldwide crop resources need to be used. This study explores the potential of mung bean in the U.S. northern latitudes through the utilization of the USDA germplasm resources. Complete collection of USDA mung bean germplasm was screened under Iowa field conditions in 2017, to shortlist 482 accessions to create an Iowa mung bean panel. The Iowa mung bean 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 trait (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 quantitative trait locus (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 indicate potential for mung bean improvement to suit midwestern U.S. cultivation. [ABSTRACT FROM AUTHOR]