2iP Y BRASINOSTEROIDES PROMUEVEN LA INDUCCIÓN DE LA EMBRIOGÉNESIS SOMÁTICA EN Theobroma cacao L.

Objective: To evaluate the effect of explant type, phytoregulators and brassinosteroid in somatic embryos induction in Theobroma cacao L. genotypes. Design/methodology/approach: Completely randomized design with factorial arrangement 3 X 4 X 2 X 2 was used. Three genotypes were evaluated (Carmelo, H13xUF-273 and PA-169xUF-273), four combinations of phytoregulators (4.52 ?M 2,4-D/ 1.16 ?M Kinetin; 4.52 ?M 2,4-D/0.02 ?M 2ip; 4.52 ?M 2, 4-D/0.02 ?M TDZ; 4.52 ?M 2, 4-D/3.91 ?M 2, 4, 5-T), two explants (petal/staminodium) and absence and presence of 0.02 ?M of 24-epibrassinolide. Forty-eight treatments were incubated in darkness for 63 days. Percentage of explants with callus, explants with embryos and embryos per explant were evaluated. Results: For explants with callus, only genotype factor had significant differences, so H13xUF-273 induced highest percentages (87%); for explants with embryos, culture medium with 2,4-D (4.52 µM)/2ip (0.02 µM) presented highest values ??for somatic embryos induction (n=44). In treatment of staminodium with 2,4-D/2ip and epibrassinolide, Carmelo genotype induced one embryo per explant; while H13xUF-273 in treatment of petals with 2,4-D/2ip and without epibrassinolide induced 1.7 embryos per explant. In PA-169xUF-273, 0.5 embryos were obtained per explant with staminodes in 2,4-D/kinetin and epibrassinolide. Limitations on study/implications: In three genotypes, petal explants without epibrassinolide were more prone to develop roots of the initially formed callus. Findings/conclusions: Genotypes evaluated have different embryogenic capacity, although the combination of 2iP with epibrassinolide improves the induction of embryos and obtaining complete plants.