High-Frequency Adventitious Shoot Regeneration from Leaf Explants of Jatropha curcas L.

Jatropha curcas L. is an important biofuel plant, but its narrow cultivation range and low seed yield limit its large-scale commercialization. Both genetic improvement and the large-scale clonal propagation of elite genotypes require an efficient and reliable regeneration system. In this study, a high-frequency adventitious shoot regeneration protocol was developed using leaf explants from one-year-old greenhouse-grown plants derived from seeds. An L9(33) orthogonal design was employed to optimize the concentrations of plant growth regulators (PGRs). The optimal combination for adventitious shoot induction was 1.0 mg·L−1 TDZ, 0.5 mg·L−1 IBA, and 1.5 mg·L−1 BA. Furthermore, the effect of sodium nitroprusside (SNP), a nitric oxide donor, was investigated. Supplementation with 2.0 mg·L−1 SNP significantly increased both the regeneration frequency and the shoot number per explant when compared to the control. Leaf maturity also significantly influenced the regeneration capacity, with the fourth expanded leaf at the light-green stage showing the greatest response. Under optimized conditions, including PGRs, SNP, and appropriate explant maturity, adventitious shoots were observed within 4 weeks, with a regeneration frequency of 88.0% and an average of 18.7 shoots per explant. This system provides a practical basis for the propagation and genetic improvement of J. curcas.