AUTHOR=Wang Ji-Peng , Munyampundu Jean-Pierre , Xu You-Ping , Cai Xin-Zhong 

TITLE=Phylogeny of Plant Calcium and Calmodulin-Dependent Protein Kinases (CCaMKs) and Functional Analyses of Tomato CCaMK in Disease Resistance

JOURNAL=Frontiers in Plant Science

VOLUME=6

YEAR=2015

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2015.01075

DOI=10.3389/fpls.2015.01075

ISSN=1664-462X

ABSTRACT=<p>Calcium and calmodulin-dependent protein kinase (<italic>CCaMK</italic>) is a member of calcium/calmodulin-dependent protein kinase superfamily and is essential to microbe- plant symbiosis. To date, the distribution of <italic>CCaMK</italic> gene in plants has not yet been completely understood, and its function in plant disease resistance remains unclear. In this study, we systemically identified the <italic>CCaMK</italic> genes in genomes of 44 plant species in Phytozome and analyzed the function of tomato <italic>CCaMK</italic> (<italic>SlCCaMK</italic>) in resistance to various pathogens. CCaMKs in 18 additional plant species were identified, yet the absence of <italic>CCaMK</italic> gene in green algae and cruciferous species was confirmed. Sequence analysis of full-length CCaMK proteins from 44 plant species demonstrated that plant <italic>CCaMKs</italic> are highly conserved across all domains. Most of the important regulatory amino acids are conserved throughout all sequences, with the only notable exception being observed in N-terminal autophosphorylation site corresponding to Ser 9 in the <italic>Medicago truncatula CCaMK</italic>. <italic>CCaMK</italic> gene structures are similar, mostly containing six introns with a phase profile of 200200 and the exception was only noticed at the first exons. Phylogenetic analysis demonstrated that CCaMK lineage is likely to have diverged early from a calcium-dependent protein kinase (CDPK) gene in the ancestor of all nonvascular plant species. The <italic>SlCCaMK</italic> gene was widely and differently responsive to diverse pathogenic stimuli. Furthermore, knock-down of <italic>SlCCaMK</italic> reduced tomato resistance to <italic>Sclerotinia sclerotiorum</italic> and <italic>Pseudomonas syringae</italic> pv. <italic>tomato</italic> (<italic>Pst</italic>) DC3000 and decreased H<sub>2</sub>O<sub>2</sub> accumulation in response to <italic>Pst</italic> DC3000 inoculation. Our results reveal that <italic>SlCCaMK</italic> positively regulates disease resistance in tomato via promoting H<sub>2</sub>O<sub>2</sub> accumulation. <italic>SlCCaMK</italic> is the first <italic>CCaMK</italic> gene proved to function in plant disease resistance.</p>