Tang Chen, Li Tianyu, Klosterman Steven J, Tian Chengming, Wang Yonglin
Beijing Key Laboratory for Forest Pest Control, College of Forestry, Beijing Forestry University, Beijing, 100083, China.
United States Department of Agriculture, Agricultural Research Service, Crop Improvement and Protection Research Unit, Salinas, CA, 93905, USA.
New Phytol. 2020 Jun;226(5):1461-1479. doi: 10.1111/nph.16481. Epub 2020 Mar 16.
The fungus Verticillium dahliae causes vascular wilt disease on hundreds of plant species. Homologs of the bZIP transcription factor Atf1 are required for virulence in most pathogenic fungi, but the molecular basis for their involvement is largely unknown. We performed targeted gene deletion, expression analysis, biochemistry and pathogenicity assays to demonstrate that VdAtf1 governs pathogenesis via the regulation of nitrosative resistance and nitrogen metabolism in V. dahliae. VdAtf1 controls pathogenesis via the regulation of nitric oxide (NO) resistance and inorganic nitrogen metabolism rather than oxidative resistance and is important for penetration peg formation in V. dahliae. VdAtf1 affects ammonium and nitrate assimilation in response to various nitrogen sources. VdAtf1 may be involved in regulating the expression of VdNut1. VdAtf1 responds to NO stress by strengthening the fungal cell wall, and by causing over-accumulation of methylglyoxal and glycerol, which in turn impacts NO detoxification. We also verified that the VdAtf1 ortholog in Fusarium graminearum mediates nitrogen metabolism, suggesting conservation of this function in related plant pathogenic fungi. Our findings revealed new functions of VdAtf1 in pathogenesis, response to nitrosative stress and nitrogen metabolism in V. dahliae. The results provide novel insights into the regulatory mechanisms of the transcription factor VdAtf1 in virulence.
大丽轮枝菌可导致数百种植物发生维管束萎蔫病。在大多数致病真菌中，bZIP转录因子Atf1的同源物是致病力所必需的，但它们发挥作用的分子基础 largely unknown。我们进行了靶向基因缺失、表达分析、生物化学和致病性测定，以证明VdAtf1通过调节大丽轮枝菌的亚硝化抗性和氮代谢来控制发病机制。VdAtf1通过调节一氧化氮（NO）抗性和无机氮代谢而非氧化抗性来控制发病机制，并且对大丽轮枝菌中侵染钉的形成很重要。VdAtf1响应各种氮源影响铵和硝酸盐同化。VdAtf1可能参与调节VdNut1的表达。VdAtf1通过强化真菌细胞壁以及导致甲基乙二醛和甘油过度积累来响应NO胁迫，进而影响NO解毒。我们还证实，禾谷镰刀菌中的VdAtf1直系同源物介导氮代谢，表明这种功能在相关植物致病真菌中具有保守性。我们的研究结果揭示了VdAtf1在大丽轮枝菌发病机制、对亚硝化胁迫的响应和氮代谢中的新功能。这些结果为转录因子VdAtf1在致病力中的调控机制提供了新的见解。
