Global analysis of transcriptional response of Chinese cabbage to methyl jasmonate reveals JA signaling on enhancement of secondary metabolism pathways

- A RNA-Seq analysis was conducted for MeJA-treated Chinese cabbage.
- 1674 annotated DEGs were related to metabolic pathways.
- Fourteen genes involved in JA biosynthesis pathway were up-regulated.
- Genes encoding sugar catabolism and some amino acids synthesis were also up-regulated.
- Glucosinolate level was highly increased with induced biosynthesis genes.

Methyl jasmonate (MeJA) is known to increase multiple resistance and secondary metabolism pathways in Brassicaceae (Cruciferae). However, the mechanisms of regulation at the transcriptomic level were not well studied. So, we conducted a RNA-Seq analysis of MeJA-treated Chinese cabbage leaf transcriptome. Among 27,461 detected genes, 1451 genes were up-regulated and 991 genes were down-regulated as differentially expressed genes (DEGs) (log2 of the fold change in gene expression ≥1, false discovery rate ≤0.001). More than 90% of the DEGs were between 2.0- and 8.0-fold changes. The most highly represented pathways by 1674 annotated DEGs were related to “metabolic pathways” (333 members). Fourteen genes involved in JA biosynthesis pathway were up-regulated. Forty genes for glucosinolate biosynthesis were induced, and the level of indole glucosinolate was highly increased by MeJA treatment. Several selected genes involved in JA signaling and indole glucosinolate synthesis pathways were validated by quantitative RT-PCR. The results expand our understanding of the complex molecular events on JA-induced plant resistance and accumulation of secondary metabolites.