In vitro DIRECT ORGANOGENESIS INDUCTION IN Phaseolus vulgaris L.

Abstract

In vitro plant tissue culture represents a complementary method for conventional plant breeding; however, some species, such as Phaseolus vulgaris L., have limited organogenic a bility. These obstacles lead to development of specific protocols, and to identify genotypes with high in vitro regeneration capability. This study was carried out to develop appropriated protocols for maximum induction of direct organogenesis, and to characterize in vitro regeneration capability in the dry bean varieties P-48, P-4, P-20, P-31, and Jamapa. As result, the highest response in induction of adventitious shoots was obtained by cotyledons grown in a medium containing, inorganic salts of Gomborg (1976, B5) basal medium, supplemented with organic compounds of the Murashige and Shoog (1962, MS), basal medium; sucrose (commercial sugar) (3 % w/v); BAP (79.9 µ M) and agar (0.6 %, w/v). Significant statistical differences in regeneration related traits were found among varieties. P-48 showed the highest response in both rate of explants with shoots (77.1 %) and number of shoots per explant (3.4), with shoots 5.68 mm long; in contrast, Jamapa had the lowest response in both rate of explants with shoots (35 %) and number of shoots per explant (0.75), with shoots 5.75 mm long. The other three
varieties showed an intermediate performance. Besides, histological studies showed that the shoots were adventitious, since they were directly originated from recently developed meristematic areas in subepidermal tissue, at the lowest area of the cotiledonary axilar bud.