Department of Biology, Section of Genetics, Cell Biology and Development, University of Patras, 26100 Patras, Greece.
Fungal Biol. 2010 May-Jun;114(5-6):387-95. doi: 10.1016/j.funbio.2010.01.010. Epub 2010 Mar 11.
This study shows that the direct indicator of oxidative stress superoxide radical (O·₂⁻) is involved in the sclerotial differentiation of the phytopathogenic filamentous fungi Rhizoctonia solani, Sclerotinia sclerotiorum, Sclerotium rolfsii, and Sclerotinia minor. The production rate of O·₂⁻ and the antioxidant enzyme superoxide dismutase (SOD) levels in the sclerotiogenic fungi were significantly higher and lower, respectively, than those of their non-differentiating counterpart strains, which strongly suggests that the oxidative stress of the sclerotium differentiating fungi is higher than that of the non-differentiating ones. Xanthine oxidase (XO), which was detected for the first time in fungi in general, was localized in the cytoplasmic membrane. The contribution of XO in the overall O·₂⁻production was very significant, reaching 30-70% among the strains, especially in the transition developmental stage between the undifferentiated and the differentiated state, suggesting a sclerotium triggering and a phytopathogenic role of XO during plant infection. The additional finding that these fungi secrete extracellular SOD can be related to their protection from the response of plants to produce O·₂⁻ at infection sites.
本研究表明，活性氧自由基超氧阴离子（O·₂⁻）这一直接的氧化应激指标参与了植物病原丝状真菌立枯丝核菌、核盘菌、齐整小核菌和小核盘菌的菌核分化。产生活性氧自由基超氧阴离子（O·₂⁻）的速率和抗氧化酶超氧化物歧化酶（SOD）的水平在菌核分化真菌中显著更高和更低，分别比它们的非分化对照菌株，这强烈表明菌核分化真菌的氧化应激高于非分化的菌核分化真菌。黄嘌呤氧化酶（XO），它在真菌中是首次被发现，定位于质膜上。XO 在总 O·₂⁻产生中的贡献非常显著，在菌株中达到 30-70%，特别是在未分化和分化状态之间的过渡发育阶段，这表明 XO 在植物感染过程中具有触发菌核形成和植物病原的作用。另外发现这些真菌分泌细胞外 SOD 可以与它们免受植物响应以在感染部位产生 O·₂⁻的保护有关。
