Abstract

The major limitation in large-scale cultivation of Jatropha curcas for use as energy crop is the inconsistent and unstable seed yield due to the heterozygous nature of the plant. A reliable in vitro regeneration system is necessary for continuous supply of quality planting material at large-scale. In this study, the interaction between the season collection of explants and capacity of in vitro regeneration shoots from foliar explants was investigated. Three genotypes selected in our breeding program were evaluated. We achieved an average of 39.8, 25.5 and 10.9 shoots per explant for G1, G2 and G3 genotypes, respectively. All genotypes showed higher regeneration capacity when the foliar explants were collected in September/2012 season. Excellent results were obtained with the use of micrografting technique for the in vitro rooting, with a plant recovery rate of 85%. In order to confirm the genetic stability of micropropagated shoots, two analyses were performed: ploidy estimation using flow cytometry and DNA polymorphism analysis using TRAP molecular markers, which has been here reported for the first time for J. curcas. For G1 genotype, it was found that 4% of the plants were tetraploid and 5% of plants had polymorphic bands. No DNA polymorphisms were found in plants of other genotypes. Thus, the low or no somaclonal variation indicates that the protocol established preserves the clonal fidelity of micropropagated plants.

Key words: Organogenesis, in vitro micrografting, foliar explants.

Abbreviation

BAP, 6-Benzylaminopurine; GA₃, gibberellic acid; IBA, indole-3-butyric acid; MS, Murashige and Skoog medium; TDZ, Thidiazuron; TRAP, target region amplification polymorphism.