The Calcium-Dependent Protein Kinase CPK28 Regulates Development by Inducing Growth Phase-Specific, Spatially Restricted Alterations in Jasmonic Acid Levels Independent of Defense Responses in Arabidopsis

Abstract

Phytohormones play an important role in development and stress adaptations in plants, and several interacting hormonal pathways have been suggested to accomplish fine-tuning of stress responses at the expense of growth. This work describes the role played by the CALCIUM-DEPENDENT PROTEIN KINASE CPK28 in balancing phytohormone-mediated development in Arabidopsis thaliana, specifically during generative growth. cpk28 mutants exhibit growth reduction solely as adult plants, coinciding with altered balance of the phytohormones jasmonic acid (JA) and gibberellic acid (GA). JA-dependent gene expression and the levels of several JA metabolites were elevated in a growth phase-dependent manner in cpk28, and accumulation of JA metabolites was confined locally to the central rosette tissue. No elevated resistance toward herbivores or necrotrophic pathogens was detected for cpk28 plants, either on the whole-plant level or specifically within the tissue displaying elevated JA levels. Abolishment of JA biosynthesis or JA signaling led to a full reversion of the cpk28 growth phenotype, while modification of GA signaling did not. Our data identify CPK28 as a growth phase-dependent key negative regulator of distinct processes: While in seedlings, CPK28 regulates reactive oxygen species-mediated defense signaling; in adult plants, CPK28 confers developmental processes by the tissue-specific balance of JA and GA without affecting JA-mediated defense responses.

A salivary EF-hand calcium-binding protein of the brown planthopper Nilaparvata lugens functions as an effector for defense responses in rice

“…These findings suggest that NlSEF1 secreted by BPH saliva can modulate the H 2 O 2 -mediated signaling pathways in rice plants. Ca 2+ transients in plants elicited by herbivore infestation are well known to directly or indirectly regulate diverse signaling pathways, such as those mediated by JA, SA, reactive oxygen species (ROS) and NO, which subsequently regulate plant defenses394041. AtSR1, a CaM-binding protein, for example, has been reported to negatively regulate the production of SA by suppressing the expression of EDS1, a positive modulator of SA biosynthesis42.…”

A fungal endophyte helps plants to tolerate root herbivory through changes in gibberellin and jasmonate signaling

“…Mechanisms of JA-mediated growth inhibition in aboveground plant organs have been demonstrated for A. thaliana, N. attenuata and rice (Yang et al, 2012;Heinrich et al, 2013;Matschi et al, 2015). The current conception is that modulation of GA biosynthesis and JAZ interference with the interaction between DELLAs and growth-promoting PIF transcription factors are two key mechanisms leading to JA-mediated growth inhibition.…”

“…The perception of above-ground chewing herbivory by plants triggers a sophisticated defensive machinery with jasmonic acid (JA) as the central signal (Howe & Jander, 2008). JA can also reduce shoot growth via antagonistic interaction with the GA signaling pathway (Yang et al, 2012;Heinrich et al, 2013;Matschi et al, 2015). Regulation of GA biosynthesis and interactions between DELLA and JAZ proteins are central to JA and GA signaling crosstalk which ultimately modulates growth-defense tradeoff in shoots.…”

Reduced Biosynthesis of Digalactosyldiacylglycerol, a Major Chloroplast Membrane Lipid, Leads to Oxylipin Overproduction and Phloem Cap Lignification in Arabidopsis

“…Methyl jasmonate treatment of Arabidopsis cells results in the increased expression of genes involved in monolignol biosynthesis and in increased monolignol and oligolignol production (Pauwels et al, 2008). JA biosynthesis has also been shown to be necessary for hypocotyl growth inhibition in the det3 and cpk28 mutants (Brüx et al, 2008;Matschi et al, 2015). Furthermore, overexpression of the lipase DONGLE (DGL) results in JA overproduction and generates visible phenotypes of short inflorescence stems and ruffled leaves, very similar to those in dgd1 (Hyun et al, 2008).…”