CaMsrB2, pepper methionine sulfoxide reductase B2, is a novel defense regulator against oxidative stress and pathogen attack.
Reactive oxygen species (ROS) are inevitably generated in aerobic organisms as by-products of normal metabolism or as the result of defense and development. ROS readily oxidize methionine (Met) residues in proteins/peptides to form Met-R-sulfoxide or Met-S-sulfoxide, causing inactivation or malfunction of the proteins. A pepper (Capsicum annuum) methionine sulfoxide reductase B2 gene (CaMsrB2) was isolated, and its roles in plant defense were studied. CaMsrB2 was down-regulated upon inoculation with either incompatible or compatible pathogens. The down-regulation, however, was restored to the original expression levels only in a compatible interaction. Gain-of-function studies using tomato (Solanum lycopersicum) plants transformed with CaMsrB2 resulted in enhanced resistance to Phytophthora capsici and Phytophthora infestans. Inversely, loss-of-function studies of CaMsrB2 using virus-induced gene silencing in pepper plants (cv Early Calwonder-30R) resulted in accelerated cell death from an incompatible bacterial pathogen, Xanthomonas axonopodis pv vesicatoria (Xav) race 1, and enhanced susceptibility to a compatible bacterial pathogen, virulent X. axonopodis pv vesicatoria race 3. Measurement of ROS levels in CaMsrB2-silenced pepper plants revealed that suppression of CaMsrB2 increased the production of ROS, which in turn resulted in the acceleration of cell death via accumulation of ROS. In contrast, the CaMsrB2-transgenic tomato plants showed reduced production of hydrogen peroxide. Taken together, our results suggest that the plant MsrBs have novel functions in active defense against pathogens via the regulation of cell redox status.
Oh
Sang-Keun
SK
Department of Plant Science, College of Agriculture and Life Sciences, Seoul National University, Seou1, Korea.
Baek
Kwang-Hyun
KH
Seong
Eun Soo
ES
Joung
Young Hee
YH
Choi
Gyung-Ja
GJ
Park
Jeong Mee
JM
Cho
Hye Sun
HS
Kim
Eun Ah
EA
Lee
Sangku
S
Choi
Doil
D
D000222:Adaptation, Physiological / Q000235:genetics / Q000276:immunology; D000595:Amino Acid Sequence; D002212:Capsicum / Q000201:enzymology* / Q000235:genetics / Q000276:immunology* / Q000382:microbiology; D016923:Cell Death; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D006861:Hydrogen Peroxide / Q000378:metabolism; D007113:Immunity, Innate / Q000276:immunology; D018551:Solanum lycopersicum / Q000276:immunology / Q000382:microbiology; D051150:Methionine Sulfoxide Reductases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D018384:Oxidative Stress / Q000235:genetics / Q000276:immunology*; D010838:Phytophthora / Q000502:physiology*; D010935:Plant Diseases / Q000276:immunology / Q000382:microbiology; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010942:Plant Viruses / Q000502:physiology; D021381:Protein Transport; D015398:Signal Transduction / Q000276:immunology; D013312:Stress, Physiological / Q000235:genetics / Q000276:immunology; D013347:Subcellular Fractions / Q000378:metabolism; D014774:Virulence; D014974:Xanthomonas / Q000472:pathogenicity / Q000502:physiology*
D010940:Plant Proteins; D006861:Hydrogen Peroxide; D051150:Methionine Sulfoxide Reductases