Antioxidant responses under jasmonic acid elicitation comprise enhanced production of flavonoids and anthocyanins in Jatropha curcas leaves

Jatropha curcas has significant potential for production of biodiesel and secondary metabolites with medical applications. The effect of jasmonic acid (JA) on flavonoid production and antioxidant responses in two Mexican J. curcas plants (accessions I-64 and I-52), growing under controlled environmental conditions, was studied. Foliar application of JA (0.25, 0.5, and 1.0 mM) increased flavonoid content by 3.3-fold (445.6 ± 62.2 µg QE g⁻¹ DW) at 1.0 mM in the I-64 accession after 120 h. At this time, individual flavonoid levels of kaempferol, apigenin, and vitexin were 6.8 (106.8 ± 18.6 µg g⁻¹ DW), 4.4 (15.5 ± 1.5 µg g⁻¹ DW), and 8.1 (6.27 ± 1.3 µg g⁻¹ DW) times higher than in the controls, while for the I-52 specimens, the highest increase of flavonoids occurred at 24 h. In treated I-52 plants, enhancement of 58% (74.7 ± 9.2 µg g⁻¹ DW) in anthocyanins occurred after 120 h, while in I-64 plants, they remained similar to controls. Phenylalanine ammonia lyase showed a peak of activity after 120 h in treated I-64 plants, while the I-52 accession showed peaks at 24 and 120 h. Elicited I-64 plants presented H₂O₂ levels similar to controls with a 30.6% increase in catalase (CAT) and 3.3-fold in ascorbate peroxidase (APX) activities. In elicited I-52 plants, a 2.4-fold increase in H₂O₂ concentration was related to a 65.6% decrease of CAT and a 1.8-fold increase of APX activities. Therefore, under JA elicitation, J. curcas plants increased antioxidant responses including flavonoid and anthocyanin production to maintain cell redox balance.