Association of Seed Amylose Content with Agronomic Traits and GBSS1a Haplotypes in Common Bean Landraces

Background: Common bean (Phaseolus vulgaris L.) is a valuable source of starch, proteins and minerals in the human diet. Starch, a major component of bean seeds, is composed of amylose and amylopectin and the content of amylose is important for affecting the quality of bean-derived food products. However, limited information is available on amylose assessment in bean. Methods: In this study, for a total of 300 bean landraces, we evaluated the seed amylose content and characterized twenty agronomic traits and analyzed the granule-bound starch synthase 1a (GBSS1a) gene haplotypes, which are likely to be associated with amylose content. Also, the correlation of amylose content with agronomic traits and GBSS1a gene haplotypes were determined. Result: Bean landraces showed diverse phenotypes, highly variable amylose content (39.95-63.57%) and three GBSS1a haplotypes (YP, YQ and NP). Correlation analysis revealed that seed size and seed weight were significantly correlated with amylose content and NP-type beans contained more amylose than YQ-type beans. Although these correlations could not fully explain the tremendous amount of variation in seed amylose content in bean germplasm, information on starch composition-related GBSS1a haplotypes and agronomic traits would facilitate genetic analyses and breeding research targeted toward improving the composition of bean starch.