Molecular characterization of a pepper C2 domain-containing SRC2 protein implicated in resistance against host and non-host pathogens and abiotic stresses.
Plants guard themselves against pathogen attack using multi-layered defense mechanism. Calcium represents an important secondary messenger during such defense responses. Upon examination of a pepper cDNA library, we observed that the gene CaSRC2-1 (Capsicum annum SRC2-1) was upregulated significantly in response to infection with the type II non-host pathogen Xanthomonas axonopodis pv. glycines 8 ra, which elicits a hypersensitive response. CaSRC2-1 encodes a protein that contains a C2 domain and it exhibits a high degree of homology to the protein Soybean genes regulated by cold 2 (SRC2). However, little is known about how SRC2 expression is elicited by biotic stresses such as pathogen challenge. Further sequence analysis indicated that the CaSRC2-1 C2 domain is unique and contain certain amino acids that are conserved within the C2 domains of other plants and animals. CaSRC2-1 transcription was up-regulated under both biotic and abiotic stress conditions, including bacterial and viral pathogen infection, CaCl(2) and cold treatment, but unaffected by treatment with plant defense-related chemicals such as salicylic acid, methyl jasmonic acid, ethephone, and abscisic acid. Intriguingly, under steady state conditions, CaSRC2-1 was expressed only in the root system. A CaSRC2-1-GFP fusion protein was used to determine localization to the plasma membrane. A fusion protein lacking the C2 domain failed to target the membrane but remained in the cytoplasm, indicating that the C2 domain plays a critical role in localization. Thus, CaSRC2-1 encodes a novel C2 domain-containing protein that targets the plasma membrane and plays a critical role in the abiotic stress and defense responses of pepper plants.
Kim
Young-Cheol
YC
Plant Genome Research Center, KRIBB, Daejeon, South Korea.
Kim
Soo-Yong
SY
Choi
Doil
D
Ryu
Choong-Min
CM
Park
Jeong Mee
JM
D000595:Amino Acid Sequence; D015152:Blotting, Northern; D002122:Calcium Chloride / Q000494:pharmacology; D002212:Capsicum / Q000187:drug effects / Q000235:genetics* / Q000821:virology; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D007113:Immunity, Innate / Q000235:genetics; D008353:Mannitol / Q000494:pharmacology; D008969:Molecular Sequence Data; D010802:Phylogeny; D010935:Plant Diseases / Q000235:genetics* / Q000821:virology; D010940:Plant Proteins / Q000145:classification / Q000235:genetics* / Q000502:physiology; D018517:Plant Roots / Q000187:drug effects / Q000235:genetics / Q000821:virology; D016133:Polymerase Chain Reaction; D020539:Sequence Analysis, Protein; D012965:Sodium Chloride / Q000494:pharmacology
D010940:Plant Proteins; D008353:Mannitol; D012965:Sodium Chloride; D002122:Calcium Chloride