Epsilon Archive for Student Projects

Abstract

Drought is a leading constraint to common bean (Phaseolus vulgaris L.) production, yet the genetic basis of drought‐resilient seed weight and progeny vigor remains incompletely resolved. This study integrated phenotyping of seed weight (GW100) and germination traits with genome-wide association (GWAS), and candidate-gene curation in a structured panel. Seeds originated from plants grown under either terminal drought or well-watered conditions (“maternal environments”). In this 38-accession germination subset, maternal drought reduced seed mass by ~15.3% on average, with strategy-dependent magnitudes, whereas within-environment correlations between GW100 and germination index (GI), synchrony (T80T20), or final germination rate (GR) were small and non-significant; pooled models indicated no global maternal-environment × weight interaction, pointing to predominant genotype effects on germination dynamics.

Across the harmonized panel (n = 170), GWAS identified 13 lead SNPs spanning GW100 under reference and drought conditions, GI_drought, GR_drought, and T80T20, with nine genome-wide and four suggestive signals. LD inspection motivated uniform ±150 kb core windows for downstream interpretation. Candidate mining within these windows (Phaseolus vulgaris v2.1; Arabidopsis orthologs via UniProt) yielded >130 genes overall, of which 36 were stress-related (e.g., receptor-like kinases, redox enzymes, transcription factors), alongside genes implicated in seed/reproductive biology. Colocalization supported biological plausibility, including overlaps with classic seed-size QTL (SW2.1; SL8.1), drought-yield regions on Chr09, a domestication/shattering interval around PvPdh1, and seed-quality (cooking-time) QTL plausibly linked to seed-coat properties.

Collectively, the results indicate that maternal drought commonly reduces seed mass but that progeny germination responses are genotype-structured and not well predicted by seed weight alone. The mapped loci, compact LD-anchored candidate sets, and QTL overlaps provide tractable entry points for fine-mapping and validation toward breeding for drought-resilient seed quality and yield.