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Resistance to Fusarium Head Blight and Seedling Blight in Wheat Is Associated with Activation of a Cytochrome P450 Gene

February 2010 , Volume 100 , Number  2
Pages  183 - 191

X. Li, J. B. Zhang, B. Song, H. P. Li, H. Q. Xu, B. Qu, F. J. Dang, and Y. C. Liao

First, second, third, fourth, fifth, sixth, seventh, and eighth authors: Molecular Biotechnology Laboratory of Triticeae Crops, Huazhong Agricultural University, Wuhan 430070, P.R. China, and eighth author: College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, P.R. China.

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Accepted for publication 5 October 2009.

One plant genotype displays a resistance phenotype at one development stage but a susceptible reaction to the same pathogen at another stage, which is referred to here as resistance inversion. In wheat, Fusarium head blight (FHB)-resistant cv. Sumai3 showed a Fusarium seedling blight (FSB)-susceptible reaction whereas FHB-susceptible cv. Annong8455 exhibited FSB resistance when challenged with a Fusarium asiaticum strain that produces deoxynivalenol (DON). The resistance to FHB and FSB in wheat was closely associated with expression of a plant cytochrome P450 gene in response to FHB pathogens and mycotoxins. Quantitative real-time polymerase chain reaction analyses showed that expression of nine defense-related genes in spikes and seedlings was induced by the fungal infection, in which a massive accumulation of a plant cytochrome P450 gene, CYP709C1, was clearly associated with the resistance reaction in both seedling and spike. The FHB-resistant Sumai3 accumulated 7-fold more P450 transcripts than did the FHB-susceptible Annong8455, while 84-fold more P450 transcripts were accumulated in the FSB-resistant Annong8455 than the FSB-susceptible Sumai3. A Fusarium strain with a disrupted Tri5 gene, which is not able to produce the first enzyme essential for trichothecene mycotoxin biosynthesis, also induced more P450 transcripts in FHB- and FSB-resistant cultivars. The fungal activation of the P450 gene was more profound in the FSB-resistant reaction than the FHB-resistant reaction relative to their susceptible counterparts. DON triggered a differential expression of the P450 gene with comparable patterns in spikes and seedlings in a resistance-dependent manner. These results may provide a basis for dissecting mechanisms underlying FHB and FSB resistance reactions in wheat and revealing functions of the cytochrome P450 in plant detoxification and defense.

© 2010 The American Phytopathological Society