Calmodulin-like proteins from Arabidopsis and tomato are involved in host defense against Pseudomonas syringae pv. tomato.
Complex signal transduction pathways underlie the myriad plant responses to attack by pathogens. Ca(2+) is a universal second messenger in eukaryotes that modulates various signal transduction pathways through stimulus-specific changes in its intracellular concentration. Ca(2+)-binding proteins such as calmodulin (CaM) detect Ca(2+) signals and regulate downstream targets as part of a coordinated cellular response to a given stimulus. Here we report the characterization of a tomato gene (APR134) encoding a CaM-related protein that is induced in disease-resistant leaves in response to attack by Pseudomonas syringae pv. tomato. We show that suppression of APR134 gene expression in tomato (Solanum lycopersicum), using virus-induced gene silencing (VIGS), compromises the plant's immune response. We isolated APR134-like genes from Arabidopsis, termed CML42 and CML43, to investigate whether they serve a functionally similar role. Gene expression analysis revealed that CML43 is rapidly induced in disease-resistant Arabidopsis leaves following inoculation with Pseudomonas syringae pv. tomato. Overexpression of CML43 in Arabidopsis accelerated the hypersensitive response. Recombinant APR134, CML42, and CML43 proteins all bind Ca(2+ )in vitro. Collectively, our data support a role for CML43, and APR134 as important mediators of Ca(2+)-dependent signals during the plant immune response to bacterial pathogens.
Chiasson
David
D
Department of Biology, Queen's University, K7L 3N6, Kingston, ON, Canada.
Ekengren
Sophia K
SK
Boyce Thompson Institute for Plant Research, Ithaca, NY, 14853, USA.
Martin
Gregory B
GB
Boyce Thompson Institute for Plant Research, Ithaca, NY, 14853, USA.|Department of Plant Pathology, Cornell University, Ithaca, NY, 14853, USA.
Dobney
Stephanie L
SL
Department of Biology, Queen's University, K7L 3N6, Kingston, ON, Canada.
Snedden
Wayne A
WA
Department of Biology, Queen's University, K7L 3N6, Kingston, ON, Canada. sneddenw@biology.queensu.ca.
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000382:microbiology*; D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000235:genetics*; D002135:Calcium-Binding Proteins / Q000737:chemistry* / Q000235:genetics*; D002147:Calmodulin / Q000235:genetics* / Q000378:metabolism*; D017124:Conserved Sequence; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D052139:Intracellular Calcium-Sensing Proteins / Q000737:chemistry* / Q000235:genetics*; D018551:Solanum lycopersicum / Q000235:genetics / Q000382:microbiology*; D008969:Molecular Sequence Data; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology*; D044224:Pseudomonas syringae / Q000502:physiology*; D017386:Sequence Homology, Amino Acid
D029681:Arabidopsis Proteins; C575861:CML42 protein, Arabidopsis; C586753:CML43 protein, Arabidopsis; D002135:Calcium-Binding Proteins; D002147:Calmodulin; D052139:Intracellular Calcium-Sensing Proteins