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Molecular mechanism of reactive oxygen species in regulating the development and pathogenicity of Botrytis cinerea

Shiping Tian: Institute of Botany, Chinese Academy of Sciences

<div>Reactive oxygen species (ROS) play crucial role in the interaction between plants and pathogens. NADPH oxidase complex (Nox) is the major enzymatic producer of ROS in eukaryotic cell. However, the underlying molecular mechanism of Nox remains largely unknown in <em>Botrytis cinerea</em>, a notorious necrotrophic plant pathogen. We found that the knockout mutant of BcNoxR, the regulatory subunit of Nox, exhibited reduced growth, sporulation, virulence, and altered ROS distribution. The protein abundance of 6-phosphogluconate dehydrogenase (BcPGD) and actin (BcActin) could be influenced by BcNoxR. Genetic analysis indicated that BcPGD and BcActin were critical pathogenic determinants. Moreover, the polymerization of actin cytoskeleton was disturbed in <em>∆bcnoxR</em>. We also proved that BcNoxR could regulate the secretion of extracellular proteins, including some pathogenic factors. Analysis of redox proteomics revealed that BcNoxR was essential for maintaining the equilibrium of redox status in <em>B. cinerea</em>. Cys thiols in <em>∆bcnoxR </em>mutant were more oxidized than those in wild-type. In addition, we further confirmed that aquaporin AQP8 is a key regulator in the ROS transport and distribution. Deletion of <em>AQP8</em> completely inhibited the development infection structures and disturbed polarity distribution of ROS in <em>B. cinerea</em>. These data lead to a better understanding of the ROS production, transport, and regulatory roles in development and pathogenicity of necrotrophic pathogens.</div>