Genetics of Stigma Shape, Cotyledon Position, and Flower Color in Reciprocal Crosses Between Phaseolus vulgaris L. and Phaseolus coccineus (Lam.) and Implications in Breeding1

Phaseolus coccineus was found to be cross-pollinated because of extrorse stigmas, hairs around the stigmas, and dehiscence of self-pollen on stylar hairs below the stigmas. Phaseolus coccineus was found to be self-fertile when self pollen was pushed through the stigmatic hairs onto the stigmatic surface. Application of White's nutrient solution to P. coccineus stigma surfaces prior to pollination with P. vulgaris pollen resulted in pollen germination and fertilization. Mature seed with viable hybrid embryos developed in pods with partially broken pedicels and in those removed from the plant and cultured in sealed ‘Ziploc’ bags. Use of these techniques open up new possibilities in bean breeding. Pollen viability was high in the F 1 P. coccineus × P. vulgaris , but low in the reciprocal F 1 . Stigma shape of P. coccineus was dominant in the former F 1 but not dominant in the reciprocal. Stigma shape, hairiness of stigma, and cotyledon position were inherited quantitatively in the cross P. vulgaris × P. coccineus , while discrete segregation for cotyledon position was observed in the reciprocal cross. Cotyledon position, stigma shape, hairiness and flower color were controlled by cytoplasmic as well as genic factors.