The Arabidopsis PARAQUAT RESISTANT2 gene encodes an S-nitrosoglutathione reductase that is a key regulator of cell death.
Metabolism of S-nitrosoglutathione (GSNO), a major biologically active nitric oxide (NO) species, is catalyzed by the evolutionally conserved GSNO reductase (GSNOR). Previous studies showed that the Arabidopsis GSNOR1/HOT5 gene regulates salicylic acid signaling and thermotolerance by modulating the intracellular S-nitrosothiol level. Here, we report the characterization of the Arabidopsis paraquat resistant2-1 (par2-1) mutant that shows an anti-cell death phenotype. The production of superoxide in par2-1 is comparable to that of wild-type plants when treated by paraquat (1,1'-dimethyl-4,4'-bipyridinium dichloride), suggesting that PAR2 acts downstream of superoxide to regulate cell death. PAR2, identified by positional cloning, is shown to be identical to GSNOR1/HOT5. The par2-1 mutant carries a missense mutation in a highly conserved glycine, which renders the mutant protein unstable. Compared to wild type, par2-1 mutant has a higher NO level, as revealed by staining with 4,5-diaminofluorescein diacetate. Consistent with this result, wild-type plants treated with an NO donor display resistance to paraquat. Interestingly, the GSNOR1/HOT5/PAR2 protein level, other than its steady-state mRNA level, is induced by paraquat, but is reduced by NO donors. Taken together, these results suggest that GSNOR1/HOT5/PAR2 plays an important role in regulating cell death in plant cells through modulating intracellular NO level.
Chen
Ruiqiang
R
State Key Laboratory of Plant Genomics and National Plant Gene Research Center (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
Sun
Shulan
S
Wang
Chun
C
Li
Yansha
Y
Liang
Yan
Y
An
Fengying
F
Li
Chao
C
Dong
Haili
H
Yang
Xiaohui
X
Zhang
Jian
J
Zuo
Jianru
J
D000595:Amino Acid Sequence / Q000235:genetics; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism*; D016923:Cell Death / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000235:genetics; D005980:Glutathione Reductase / Q000235:genetics* / Q000378:metabolism*; D005998:Glycine / Q000235:genetics; D006540:Herbicides / Q000494:pharmacology; D020125:Mutation, Missense / Q000235:genetics; D009569:Nitric Oxide / Q000378:metabolism; D020030:Nitric Oxide Donors / Q000494:pharmacology; D010269:Paraquat / Q000494:pharmacology
D029681:Arabidopsis Proteins; D006540:Herbicides; D020030:Nitric Oxide Donors; D009569:Nitric Oxide; D005980:Glutathione Reductase; C521253:S-nitrosoglutathione reductase, Arabidopsis; D010269:Paraquat; D005998:Glycine