Cloning and characterization of a MeJA-responsive jasmonate ZIM-domain gene (SmJAZ1) from Salvia miltiorrhiza Bunge

Methyl jasmonate (MeJA) has an important role in modulating the accumulation of secondary metabolites in Salvia miltiorrhiza Bunge. However, little research has been reported on genes involved in the JA signaling pathway in this species. Jasmonate ZIM-domain (JAZ) transcriptional repressors are the key regulators of the hormonal response. We cloned a novel JAZ gene, SmJAZ1, from S. miltiorrhiza by screening its transcriptome database. Its full-length sequence is 2024 bp long, including a 1308-bp promoter, and comprises two introns and three exons that encode a polypeptide of 180 amino acid residues. The predicted SmJAZ1 contains the ZIM domain and Jas domain, which are highly conserved regions in the JAZ family. Most JAZ genes can be induced by treatment with MeJA or wounding, a phenomenon that is characteristic of JAZs. Similar to other JAZ genes, our real-time quantitative PCR analysis showed that SmJAZ1 expression increased rapidly, by 2.1-fold, within 1 h after MeJA treatment. It was also strongly induced, to 6.0-fold, within 0.5 h after wounding. Therefore, we believe that this gene is a member of the JAZ family. Although it was detected in four tissues examined here, expression was significantly elevated in the stems and leaves. This gene also responded to treatments with other phytohormones and plant growth regulators (ABA, gibberellin, naphthalene acetic acid, and salicylic acid) and to low-temperature stress. The results obtained provide general characteristics for SmJAZ1 and contribute to our understanding of the jasmonate signaling pathway in S. miltiorrhiza.