Mungbean (Vigna radiata (L.) Wilczek) is a drought-tolerant, short-season crop taking between 60-90 days from planting to harvest, with a composition of 22-28% protein, 1-1.5% fat, 60-65% carbohydrates, and valuable minerals, vitamins, and antioxidants. We explored the phenotypic and genotypic diversity of 367 mungbean genotypes in the Iowa diversity panel by analyzing over 9000 images collected at three-time points (days 12, 15, 18), generated using a hydroponic system, with root structure architecture (RSA) traits extracted using the Automated Root Image Analysis (ARIA) software. Using association studies, we identified significant markers associated with lateral root angle (LRA) and length distribution (LED). Day 15 broad-sense heritabilities (H) ranged from 0.22-0.73. Lateral Root Angle (LRA) and width (WID) had the lowest and highest heritabilities at 0.22 and 0.73 respectively. Broad sense heritabilities for days 15 and 18 were higher than those for day 12. Using root ideotype classification, genotypes PI425425 (India), PI425045 (Philippines), PI425551 (Korea), PI264686 (Philippines), PI425085 (Sri Lanka) emerged top five in the topsoil foraging category while PI425594 (Unknown origin), PI425599 (Thailand), PI425610 (Afghanistan), PI425485 (India), AVMU0201 (Taiwan) were top five in the “steep, cheap, and deep” ideotype. We identified candidate genotypes that can now be advanced to the greenhouse or field for further testing. Taken together, the wide phenotypic variation, the ideotypes after field evaluation, and the significant markers can be utilized as tools for marker-assisted selection and crop improvement for mungbean breeding.

Mung bean (Vigna radiata (L.) Wilczek) is an important crop providing protein, fiber, carbohydrates, and minerals in Southeast Asia and Africa. Trifoliate leaves in mung beans are central to several plant processes like photosynthesis, light interception, early disease & pest warning signals, and overall canopy architecture. We sampled more than 5000 leaf images of the Iowa Mung bean diversity panel (IMDP) during the 2020 and 2021 growing seasons in a Randomized Complete Block Design. We recorded the phenotypic diversity, developed a regression model for the oval leaflet type, and conducted GWAS for the image extracted traits. The diversity in the morphology included leaflet type (oval or lobed), leaflet size (small, medium, large), lobed angle (shallow, deep), and vein coloration (green, purple). A universal regression model LA = b0 + b1L + b2W + b3L*W was the best at predicting the area of each ovate leaflet with an adjusted R2 of 0.97. The candidate genes Vradi01g07560, Vradi05g01240, Vradi02g05730, and Vradi03g00440 are associated with multiple traits (length, width, perimeter, and area) across the leaflets (left, terminal, and right) and would be suitable candidates for further investigation in their role in leaf development, growth, and function. Future studies will be needed to correlate the observed traits discussed here with yield or important agronomic traits for use as phenotypic or genotypic markers in marker-aided selection methods for mung bean crop improvement.