Plastidial glutathione reductase from Haynaldia villosa is an enhancer of powdery mildew resistance in wheat (Triticum aestivum).
A full-length cDNA (Hv-GR) whose transcript accumulation increased in response to infection by Blumeria graminis DC.f.sp. tritici (Bgt) was isolated from Haynaldia villosa. Southern analysis revealed a single copy of Hv-GR present in H. villosa. This gene encodes a glutathione reductase (GR) with high similarity to chloroplastic GRs from other plant species. Chloroplastic localization of Hv-GR was confirmed by targeting of the green fluorescent protein (GFP)-Hv-GR fusion protein to chloroplasts of epidermal guard cells. Following inoculation with Bgt, transcript accumulation of Hv-GR increased in a resistant line of wheat, but no significant change was observed in a susceptible line. In vivo function of Hv-GR in converting oxidized glutathione (GSSG) to the reduced form (GSH) was verified through heterologous expression of Hv-GR in a yeast GR-deficient mutant. As expected, overexpression of this gene resulted in increased resistance of the mutant to H(2)O(2), indicating a critical role for Hv-GR in protecting cells against oxidative stress. Moreover, overexpression of Hv-GR in a susceptible wheat variety, Triticum aestivum cv. Yangmai 158, enhanced resistance to powdery mildew and induced transcript accumulation of other pathogenesis-related genes, PR-1a and PR-5, through increasing the foliar GSH/GSSG ratio. Therefore, we concluded that a high ratio of GSH to GSSG is required for wheat defense against Bgt, and that chloroplastic GR enzymes might serve as a redox mediator for NPR1 activation.
Chen
Ya-Ping
YP
The National Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, PR China.
Xing
Li-Ping
LP
Wu
Guo-Jiang
GJ
Wang
Hua-Zhong
HZ
Wang
Xiu-E
XE
Cao
Ai-Zhong
AZ
Chen
Pei-Du
PD
D000595:Amino Acid Sequence; D001483:Base Sequence; D017931:DNA Primers; D020224:Expressed Sequence Tags; D005658:Fungi / Q000472:pathogenicity*; D005980:Glutathione Reductase / Q000378:metabolism*; D008969:Molecular Sequence Data; D018087:Plastids / Q000201:enzymology*; D017386:Sequence Homology, Amino Acid; D014908:Triticum / Q000382:microbiology*
D017931:DNA Primers; D005980:Glutathione Reductase