Chen Li-Hung, Tsai Hsieh-Chin, Yu Pei-Ling, Chung Kuang-Ren
Department of Plant Pathology, College of Agriculture and Natural Resources, National Chung-Hsing University, Taichung, Taiwan.
Biotechnology Center, NCHU, Taichung, Taiwan.
PLoS One. 2017 Jan 6;12(1):e0169103. doi: 10.1371/journal.pone.0169103. eCollection 2017.
Major Facilitator Superfamily (MFS) transporters play an important role in multidrug resistance in fungi. We report an AaMFS19 gene encoding a MFS transporter required for cellular resistance to oxidative stress and fungicides in the phytopathogenic fungus Alternaria alternata. AaMFS19, containing 12 transmembrane domains, displays activity toward a broad range of substrates. Fungal mutants lacking AaMFS19 display profound hypersensitivities to cumyl hydroperoxide, potassium superoxide, many singlet oxygen-generating compounds (eosin Y, rose Bengal, hematoporphyrin, methylene blue, and cercosporin), and the cell wall biosynthesis inhibitor, Congo red. AaMFS19 mutants also increase sensitivity to copper ions, clotrimazole, fludioxonil, and kocide fungicides, 2-chloro-5-hydroxypyridine (CHP), and 2,3,5-triiodobenzoic acid (TIBA). AaMFS19 mutants induce smaller necrotic lesions on leaves of a susceptible citrus cultivar. All observed phenotypes in the mutant are restored by introducing and expressing a wild-type copy of AaMFS19. The wild-type strain of A. alternata treated with either CHP or TIBA reduces radial growth and formation and germination of conidia, increases hyphal branching, and results in decreased expression of the AaMFS19 gene. The expression of AaMFS19 is regulated by the Yap1 transcription activator, the Hog1 and Fus3 mitogen-activated protein (MAP) kinases, the 'two component' histidine kinase, and the Skn7 response regulator. Our results demonstrate that A. alternata confers resistance to different chemicals via a membrane-bound MFS transporter.
主要易化子超家族（MFS）转运蛋白在真菌的多药耐药性中起重要作用。我们报道了一个AaMFS19基因，其编码一种MFS转运蛋白，该转运蛋白是植物病原真菌链格孢中细胞对氧化应激和杀真菌剂产生抗性所必需的。AaMFS19含有12个跨膜结构域，对多种底物具有活性。缺乏AaMFS19的真菌突变体对氢过氧化异丙苯、超氧酸钾、许多单线态氧生成化合物（伊红Y、孟加拉玫瑰红、血卟啉、亚甲蓝和 cercosporin）以及细胞壁生物合成抑制剂刚果红表现出严重的超敏反应。AaMFS19突变体对铜离子、克霉唑、咯菌腈、科赛德杀真菌剂、2-氯-5-羟基吡啶（CHP）和2,3,5-三碘苯甲酸（TIBA）的敏感性也增加。AaMFS19突变体在易感柑橘品种的叶片上诱导产生较小的坏死斑。通过导入并表达AaMFS19的野生型拷贝，可恢复突变体中观察到的所有表型。用CHP或TIBA处理链格孢的野生型菌株会降低其径向生长以及分生孢子的形成和萌发，增加菌丝分支，并导致AaMFS19基因的表达下降。AaMFS19的表达受Yap1转录激活因子、Hog1和Fus3丝裂原活化蛋白（MAP）激酶、“双组分”组氨酸激酶以及Skn7应答调节因子的调控。我们的结果表明，链格孢通过一种膜结合的MFS转运蛋白赋予对不同化学物质的抗性。
