Identification and characterization of slow darkening gene in pinto bean (Phaseolus vulgaris L.)
Islam, N., Marsolais, F. and Dhaubhadel, S. (2017) Identification and characterization of slow darkening gene in pinto bean (Phaseolus vulgaris L.) Biennial Bean Improvement Cooperative Meeting, East Lansing, MI, Oct 29-31
Postharvest darkening of seed coat in pinto bean (Phaseolus vulgaris L.) is an undesirable trait that affects its market value. Darkening is comparatively more rapid in the adapted cultivars like CDC-Pintium than the newly developed slow darkening cultivar 1533-15. A single gene, slow darkening (Sd), is responsible for the slow darkening in pinto beans and the trait co-segregates with two simple sequence repeat (SSR) markers. The objective of this research is to identify and characterize the Sd gene to understand the slow darkening mechanism in pinto bean seed coat. A search for Sd within the linkage distance from the SSR markers has identified a basic helix-loop-helix (bHLH) transcription factor gene, PvbHLH333, on chromosome 7 as a candidate gene. Our complementation assay showed PvbHLH333 is able to rescue the tt8 mutant phenotype in Arabidopsis suggesting that PvbHLH333 is the orthologue of AtTT8 which regulates proanthocyanidin biosynthesis in Arabidopsis.