IMPROVEMENT OF DIRECT REGENERATION OF MEXICAN SOYBEAN FROM COTYLEDONARY NODES

Plant tissue culture provides an alternative approach to improve the quality of soybean (Glycine max (L.) Merrill) cultivars. This study was undertaken to analyze the susceptibility of Mexican soybean for direct shoot regeneration and to determine the critical factors that affect in vitro performance. Our hypothesis was that Mexican soybean is suitable for in vitro regeneration using a cotyledonary node as explant. The effects of the seed disinfection procedure, soaking pretreatment before germination, soybean variety, as well as the culture medium composition of the shoot induction medium, were evaluated by two split-plot statistical designs. According to the statistical analysis, the seed disinfection procedure, the soaking pretreatment before germination, and the soybean genotype were the factors that brought about a significant effect (p <= 0.01), while the hormones composition of the shoot induction medium did not have a significant effect. The best response for multiple shoot formation was observed using a chlorine gas seed disinfection method, 3% hydrogen peroxide soaking pretreatment, and Huasteca-100, Nainari and Suaqui soybean genotypes. A robust protocol was developed, and under these selected conditions, it is possible to obtain more than 10 shoots per explant. Well-developed plantlets were obtained after 60 d of in vitro culture.