Seed Coat Shininess in Phaseolus vulgaris: Rescuing a Neglected Trait by Its Screening on Commercial Lines and Landraces

  •  Eneas Konzen    
  •  Siu Tsai    


Seeds with shiny seed coat in common bean (Phaseolus vulgaris L.) are normally rejected by consumers due to their difficult cooking, however they can prevent insects and pathogens injuries. Seed coat shininess is known to be conditioned by the Asp gene with the dominant form and is also influenced by the J locus. The latter influences seed coat color and pattern and has been considered a precursor for proanthocyanidin only in the presence of the dominant allele. This work aimed at performing a series of morphological, biochemical and genetic analyses for screening seed coat shininess in common bean. We showed Asp and J can be easily distinguished. Colorimeter data (L*a*b* system) can somehow provide a quantitative differentiation for seed coat shininess based on the L* variable. Palisade epidermis length and seed coat roughness profiles obtained through electronic microscopy were good indicators for Asp phenotyping. Water uptake was affected by shininess but is probably influenced by more genes, even J, or due physiological responses. A vanillin-HCl test showed to be a suitable method for tracing condensed tannins. AFLP markers partially allowed the categorization of shininess phenotypic classes. These results could be helpful regarding selection purposes and breeding. Therefore, favorable selection to Asp would lead to better resistance to pathogens and insects. J, instead, could be selected for nutritional purposes, since proanthocyanidins are important anti-oxidant and anti-carcinogenic compounds.

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