In response to jasmonates (JAs), the JA receptor Coronatine Insensitive 1 (COI1) recruits JAzinc-finger inflorescence meristem (ZIM)-domain (JAZ) family repressors for destruction to regulate plant growth, development, and defense. As Arabidopsis encodes 13 JAZ repressors, their functional specificity, diversity, and redundancy in JA/COI1-mediated responses remain unclear.We generated a broad range of jaz mutants based on their phylogenetic relationship to investigate their roles in JA responses. The group I JAZ6 may play an inhibitory role in resistance to Botrytis cinerea, group II (JAZ10)/III (JAZ11/12) in JA-regulated root growth inhibition and susceptibility to Pseudomonas syringae pv tomato DC3000, and group IV JAZ3/4/9 in flowering time delay and defense against insects. JAZs exhibit high redundancy in apical hook curvature.
The phytohormones jasmonates (JAs) control plant development, growth, and defense against insects and pathogens. The Arabidopsis JA receptor Coronatine Insensitive 1 (COI1) interacts with ARABIDOPSIS SKP-LIKE1 (ASK1)/ASK2 to form the SCF COI1 E3 ligase and mediate JA responses. Here, we performed a genetic suppressor screen using the leaky coi1-2 (COI1 Leu245Phe ) mutant for restored sensitivity to JA, and identified the intragenic suppressor mutation Leu59Phe, which was in the region connecting the F-box and leucinerich repeats domains of COI1. The L59F substitution not only restores the COI1 L245F function, but also the COI1 Gly434Glu (coi1-22 rsp ) function in JA responses, through recovering their interactions with ASK1 or ASK2 and their protein levels. The L59F change itself could not enhance the interactions between COI1 and ASK1/ 2, nor affect JA responses. The present study reveals that the Leu59Phe substitution compensates for the effect of some deleterious mutations in the JA receptor COI1.
The phytohormones jasmonates (JAs) regulate diverse aspects of plant growth and defense responses. The JA-ZIM domain (JAZ) family of repressors are targeted by the JA receptor Coronatine Insensitive 1 for ubiquitination and subsequent degradation via the 26S proteasome. We previously investigated the functions of JAZs in JA responses by analyzing
jaz
mutants of the phylogenetic group I (
jaz1/2/5/6
), group II/III (
jaz10/11/12
), group IV/V (
jaz3/4/7/9
and
jaz3/4/7/8/9
), and their high-order mutant
jaz1/2/3/4/5/6/7/9/10/11/12
. Here, we examined JA-regulated root growth, apical hook curvature, flowering time, and defense against the insect
Spodoptera exigua
in the intermediate
jaz
mutants
jaz1/2/5/6/10/11/12, jaz1/2/3/4/5/6/7/9
, and
jaz3/4/7/8/9/10/11/12
. This study shows that these
jaz
mutants differentially affect JA responses, suggesting the complexity of JA pathway in these multiple
jaz
mutants.
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