Novel explant for somatic embryogenesis in Sorghum bicolor (L.) Mohen

This work was carried out with the objective to form somatic embryos of sorghum, cv. ‘CIAP 132R-05’ starting from callus obtained from sections of in vitro shoots. For the formation of callus, different concentrations of 2,4-D were studied as well as three concentrations of ascorbic acid to eliminate the phenolic oxidation. To increase the percentage of callus formation with embryogenic structures, different segments of the shoots were used. For the formation of somatic embryos, different concentrations of 2,4-D; 6-BAP and L-Proline were added to the culture media. The greatest callus formation (50%) was obtained in the culture medium with 18.1 µM of 2,4-D. When 50 mg l -1 of ascorbic acid was added to the culture medium, the percentage of callus formation increased to 67.5%, and was couple with absence of oxidation of the medium and the explant. The frequency of callus formation with embryogenic structures increased to 95% with the use of segment 1 of the shoot sections in vitro as explant. The greatest number of somatic embryos per callus was obtained when 2,4-D was reduced to 4.52 µM, combined with 22.2 µM of 6-BAP and 500 mg l -1 of L-Proline (41.88). Histological analysis confirmed that structures formed in callus came from a somatic embryogenesis process. For the first time, the efficient formation of somatic embryos of sorghum section 1 of in vitro shoots in vitro was obtained. Keywords: 2,4-D, shoots in vitro, callus, somatic embryos