Tepary bean (Phaseolus acutifolius) is a short-lived legume native to the deserts and semi-arid regions of Northwestern Mexico and the Southwestern United States. It is resilient and adaptable to high temperatures and drought stress, ideally suited as a low-input organic cover crop in southern Texas. Tepary beans are prized for their nitrogen-fixing potential and high nutritional value. We explored the effectiveness of tepary beans and common summer legume cover crops, such as cowpea and Sunn hemp, on the productivity of subsequent vegetable crops like spinach. Additionally, we evaluated 207 USDA-GRIN undomesticated tepary bean accessions under organic production systems to assess their seed nutritional profiles. Preliminary findings indicated that spinach grown following tepary beans as a cover crop significantly enhanced biomass and exhibited nitrogen use efficiencies comparable to Sunn hemp and cowpeas. The amino acid profiles of the seeds and the total protein content across tepary bean accessions displayed significant variability. We conducted a genome-wide association study (GWAS) of seed nutritional and physiological traits using SNPs obtained through GBS. The candidate genes and loci associated with these traits could advance breeding efforts to enhance nutritional value. The study's outcomes would help affirm the potential of tepary beans as a promising summer cover crop, identifying high-value accessions with superior yield and nutritional qualities to facilitate the development of improved cultivars through introgression breeding.
