Abstract
Jasmonates (JAs) regulate various stress responses and development processes in plants, and the JA pathway is tightly controlled. In this study, we report the functional characterization of two novel RING-type ubiquitin ligases, RING DOMAIN LIGASE3 (RGLG3) and RGLG4, in modulating JA signaling. Both RGLG3 and RGLG4 possessed ubiquitin ligase activities and were widely distributed in Arabidopsis (Arabidopsis thaliana) tissues. Altered expression of RGLG3 and RGLG4 affected methyl JA-inhibited root growth and JA-inductive gene expression, which could be suppressed by the coronatine insensitive1 (coi1) mutant. rglg3 rglg4 also attenuated the inhibitory effect of JA-isoleucine-mimicking coronatine on root elongation, and consistently, rglg3 rglg4 was resistant to the coronatine-secreting pathogen Pseudomonas syringae pv tomato DC3000, suggesting that RGLG3 and RGLG4 acted in response to the coronatine and promoted JA-mediated pathogen susceptibility. In addition, rglg3 rglg4 repressed wound-stunted plant growth, wound-stimulated expression of JA-responsive genes, and wound-induced JA biosynthesis, indicating their roles in JA-dependent wound response. Furthermore, both RGLG3 and RGLG4 responded to methyl JA, P. syringae pv tomato DC3000, and wounding in a COI1-dependent manner. Taken together, these results indicate that the ubiquitin ligases RGLG3 and RGLG4 are essential upstream modulators of JA signaling in response to various stimuli.
Highlights
Jasmonates (JAs) regulate various stress responses and development processes in plants, and the JA pathway is tightly controlled
Sequence alignment showed that the five Arabidopsis RING DOMAIN LIGASEs (RGLGs) have highly similar protein sequences, with noteworthy differences in the N-terminal peptide upstream of the von Willebrand A (VWA) domain (Supplemental Fig. S1)
These results demonstrated that both RING DOMAIN LIGASE3 (RGLG3) and RGLG4 possess ubiquitin ligase activities
Summary
Jasmonates (JAs) regulate various stress responses and development processes in plants, and the JA pathway is tightly controlled. Rglg rglg repressed wound-stunted plant growth, wound-stimulated expression of JA-responsive genes, and wound-induced JA biosynthesis, indicating their roles in JA-dependent wound response. Both RGLG3 and RGLG4 responded to methyl JA, P. syringae pv tomato DC3000, and wounding in a COI1-dependent manner. Taken together, these results indicate that the ubiquitin ligases RGLG3 and RGLG4 are essential upstream modulators of JA signaling in response to various stimuli. DELLA proteins, essential negative regulators of GA signaling (Fleet and Sun, 2005), and JAZs interfere mutually in regulating growth and the defense response (Hou et al, 2010; Yang et al, 2012)
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