JA Conjugation in Grapes The hormone jasmonic acid (JA) is activated by conjugation to isoleucine. In this issue, Böttcher et al. (pp. 618–627) analyze two grapevine JA-amido synthetases, VvGH3-7 and VvGH3-9, for their roles in JA-Ile conjugate biosynthesis, berry development and stress responses. In leaves, VvGH3-9 is wounding- and JA-responsive, while VvGH3-7 seems to be induced by a mobile wounding signal.