rescue of early heart-shaped embryos and plant regeneration of phaseolus polyanthus greenm. and phaseolus vulgaris

In order to improve plant recovery from early heart-shaped Phaseolus embryos, several refinements were made to the embryo rescue technique developed previously in our laboratory. Using Phaseolus polyanthus Greenm. and Phaseolus vulgaris L. genotypes, a 20/ increase in the germination rate was obtained by using Phillips salts and 25 microg per liter ABA. This germination medium improved the development of the embryos and increased the number of normal growing plantlets. After germination, a 2-week dehydration treatment significantly stimulated the development of heart-shaped embryos into plantlets. A high variability in terms of growth and development of the embryos was observed among the P. polyanthus genotypes. A 50/ germination rate was obtained for the NI 429 genotype, compared to an average of 20/ for the other genotypes.