INDUCTION, MULTIPLICATION, AND ELONGATION OF IN VITRO SHOOTS OF ADVANCED LINES OF Phaseolus vulgaris L., Phaseolus coccineus L., AND Vigna radiata L.

Abstract

Beans are the second most important crop in Mexico and the most consumed legume in the human diet. Advances in the knowledge of its genetic diversity have allowed the identification of lines with resistance to biotic and abiotic factors. To exploit this variability, the use of in vitro culture techniques aimed at the multiplication of germplasm with economic, cultural, and nutritional value is proposed. In this research, conditions for the induction, multiplication, and shoot elongation of three advanced lines of Phaseolus vulgaris L., Phaseolus coccineus L., and Vigna radiata L. by direct organogenesis were determined. Seeds were disinfected by a sequential treatment that reached 93 % asepsis. Germination was achieved in Murashige and Skoog (MS) medium at 50 % inorganic salts after scarifying the seeds in 1 % hydrogen peroxide for 30 min. To induce organogenesis, explants were grown on MS medium with a full concentration of inorganic salts. The best results were obtained in cotyledonary nodes, with 72 µM of 6-benzyladenine (BA) for P. vulgaris (4.1 shoots) and V. radiata (6.8 shoots), and with 90 µM of BA for P. coccineus (27.9 shoots). Multiplication was most efficient in groups of 3 to 4 shoots per explant, using 72 µM of BA for P. vulgaris (6.1 shoots), 54 µM of BA for P. coccineus (30.7 shoots), and 90 µM of thidiazuron (TDZ) for V. radiata (24.6 shoots). Shoot elongation was achieved on MS medium without regulators for P. vulgaris (0.22 cm), with 5.6 µM gibberellic acid (AG₃) for P. coccineus (5.53 cm), and with 2.8 µM AG₃ for V. radiata (0.8 cm).