Somatic embryogenesis of cultivar RB966928 and clone RB986419 of sugarcane (Saccharum spp.)

Abstract

The sugar cane is a crop widely planted because of the economic importance of its products, sugar and ethanol. Brazil is the largest producer and exporter of sugar, so the crop is often inserted in breeding programs. Genetic transformation strategy is used to obtain resistant and productive cultivars. Defined and optimized in vitro regeneration protocols are required to obtain transgenic plants. The aim of this study was to evaluate the influence of different concentrations of 2,4-D (2,4-dichlorophenoxyacetic acid) to obtain embryogenic callus on cultivars RB966928 and RB986419 clone. Immature leaves from 10 months old plants were used as a source of explants. Leaf 8 x 150 mm cylinders, segmented into 4 mm were inoculated on MS medium with five concentrations of 2,4-D (1, 3, 9, 16 and 27 ?M). A second experiment was conducted with concentrations 3, 9 and 16 ?M of 2,4-D. For both experiments, the dedifferentiation occurred in the dark. Calli were transferred after 45 days of subculture to new medium with the same concentrations of origin for their multiplication. The cultivar RB966928 had responses to somatic embryogenesis of 30 and 41% using 16 ?M of 2,4-D for the first and second experiments, respectively. The clone RB986419 showed respectively 26 and 80% formation of embryogenic callus, using 9 ?M of 2,4-D in the first and second experiment. The calli were transferred to MS medium without plant growth regulator. Seedlings were acclimatized and placed in a greenhouse. The best concentrations of 2,4-D for the formation of calli were 16 ?M for the cultivar RB966928 and 9 ?M for clone RB986419.