The Calmodulin-Binding Protein IQM1 Interacts with CATALASE2 to Affect Pathogen Defense

Abstract

Calmodulin (CaM) regulates plant disease responses through its downstream calmodulin-binding proteins (CaMBPs) often by affecting the biosynthesis or signaling of phytohormones, such as jasmonic acid (JA) and salicylic acid. However, how these CaMBPs mediate plant hormones and other stress resistance-related signaling remains largely unknown. In this study, we conducted analyses in Arabidopsis (Arabidopsis thaliana) on the functions of AtIQM1 (IQ-Motif Containing Protein1), a Ca 21-independent CaMBP, in JA biosynthesis and defense against the necrotrophic pathogen Botrytis cinerea using molecular, biochemical, and genetic analyses. IQM1 directly interacted with and promoted CATALASE2 (CAT2) expression and CAT2 enzyme activity and indirectly increased the activity of the JA biosynthetic enzymes ACX2 and ACX3 through CAT2, thereby positively regulating JA content and B. cinerea resistance. In addition, in vitro assays showed that in the presence of CaM5, IQM1 further enhanced the activity of CAT2, suggesting that CaM5 may affect the activity of CAT2 by combining with IQM1 in the absence of Ca 21. Our data indicate that IQM1 is a key regulatory factor in signaling of plant disease responses mediated by JA. The study also provides new insights that CaMBP may play a critical role in the cross talk of multiple signaling pathways in the context of plant defense processes.

The dual interplay of RAV5 in activating nitrate reductases and repressing catalase activity to improve disease resistance in cassava

“…cinerea , and the suppression of AtCAT by SA regulates endogenous H 2 O 2 level and further sulphenylation of tryptophan synthetase β subunit 1, so as to regulate auxin level and disease resistance to Pseudomonas syringae (Yuan et al ., 2017). In addition, AtCAT2 interacts with calmodulin‐binding protein 1 (AtIBP1) to affect pathogen defence response (Lv et al ., 2019). Herein, MeRAV5 interacted with MeCAT1 to inhibit its activity, so as to negatively regulate endogenous H 2 O 2 level and further improve disease resistance.…”

Redox Status, JA and ET Signaling Pathway Regulating Responses to Botrytis cinerea Infection Between the Resistant Cucumber Genotype and Its Susceptible Mutant

“…Calmodulins (CaM) have been reported to be involved in plant defense responses (Kim et al, 2002;Kang et al, 2006). A Ca 2+ -independent calmodulin-binding proteins (CaMBP) affected defense against the B. cinerea in Arabidopsis (Lv et al, 2019). NtCaM1, NtCaM2 and NtCaM13 were induced by tobacco mosaic virus (TMV)-mediated hypersensitive reaction in tobacco (Takabatake et al, 2007).…”

Overexpressing the N‐terminus of CATALASE2 enhances plant jasmonic acid biosynthesis and resistance to necrotrophic pathogen Botrytis cinerea B05.10

“…In this study, we identified CAT2-N, not CAT2-C, as an accelerator for JA biosynthesis during plant resistance to B. cinerea through interacting with and promoting ACX2/3. In addition, mutation of the crucial active amino acids of CAT2, including His65, Val106, Phe143, and Tyr348, resulted in extremely low catalase activity for H 2 O 2 degradation, while these mutated CAT2 proteins still interacted with ACX2 and ACX3, and stimulated their ACX activity (Figure 2), further supporting that CAT2 promotes ACX activity at B. cinerea B05.10 than the wildtype plant (Lv et al, 2019). AtIQM1 interacts with and promotes CAT2 activity, especially in the presence of calmodulin5 (CaM5) in Arabidopsis, increasing the activity of the JA biosynthetic enzymes ACX2 and ACX3 (Lv et al, 2019).…”

“…A recent report showed that a loss‐of‐function mutant of AtIQM1 ( IQ‐Motif Containing Protein1 ), iqm1‐1 , exhibited higher resistance to biotrophic Pst DC3000 but susceptibility to necrotrophic B . cinerea B05.10 than the wildtype plant (Lv et al, 2019 ). AtIQM1 interacts with and promotes CAT2 activity, especially in the presence of calmodulin5 (CaM5) in Arabidopsis , increasing the activity of the JA biosynthetic enzymes ACX2 and ACX3 (Lv et al, 2019 ).…”

“…cinerea B05.10 than the wildtype plant (Lv et al, 2019 ). AtIQM1 interacts with and promotes CAT2 activity, especially in the presence of calmodulin5 (CaM5) in Arabidopsis , increasing the activity of the JA biosynthetic enzymes ACX2 and ACX3 (Lv et al, 2019 ). In this study, we found that overexpressing CAT2‐N in the wildtype plants did not significantly alter plant resistance to Pst DC3000 but enhanced plant resistance to B .…”