Functional Characterization of a Eukaryotic Melibiose Transporter1[OA]
Functional Characterization of a Eukaryotic Melibiose Transporter1[OA]
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DOI：
10.1104/pp.111.178624
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发表时间：
2011-05
期刊：
影响因子：
7.4
通讯作者：
Ulrike Lingner;Steffen Münch;B. Sode;H. Deising;N. Sauer
中科院分区：
文献类型：
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作者：
Ulrike Lingner;Steffen Münch;B. Sode;H. Deising;N. Sauer
病原真菌严重影响植物健康，造成作物产量和品质的重大损失。尽管它们的影响很大，但人们对这些真菌在植物中使用的碳源以及真菌从植物-真菌界面输入糖的转运体知之甚少。本文报道了半生物营养真菌禾本科炭疽菌（Colletotrichum graminicola）中MELIBIOSE TRANSPORTER1 （MBT1）的鉴定和特性，该真菌是玉米叶炭疽病和茎腐病的病原。对表达MBT1 cDNA的面包酵母（Saccharomyces cerevisiae）中MBT1蛋白的功能表征表明，α-d-半乳糖酰氨基化合物如蜜利二糖、半乳糖醇和棉子糖是MBT1的底物，其中蜜利二糖最有可能是首选底物。α-d-Glucopyranosyl双糖，如海藻糖、异麦芽糖或麦芽糖也被MBT1接受，尽管亲和度较低。MBT1基因在无性系生长的谷草曲菌和玉米叶片侵染后的初始生物营养发育和随后的坏死阶段均表现出较低的表达水平。尽管MBT1的表达水平很低，但MBT1蛋白可以使C. graminicola在melli二糖作为唯一碳源的无菌培养中高效生长。虽然Δmbt1突变体不能在二糖糖上生长，但它们在玉米上没有表现出毒力缺陷。
Pathogenic fungi drastically affect plant health and cause significant losses in crop yield and quality. In spite of their impact, little is known about the carbon sources used by these fungi in planta and about the fungal transporters importing sugars from the plant-fungus interface. Here, we report on the identification and characterization of MELIBIOSE TRANSPORTER1 (MBT1) from the hemibiotrophic fungus Colletotrichum graminicola (teleomorph Glomerella graminicola), the causal agent of leaf anthracnose and stalk rot disease in maize (Zea mays). Functional characterization of the MBT1 protein in baker’s yeast (Saccharomyces cerevisiae) expressing the MBT1 cDNA revealed that α-d-galactopyranosyl compounds such as melibiose, galactinol, and raffinose are substrates of MBT1, with melibiose most likely being the preferred substrate. α-d-Glucopyranosyl disaccharides like trehalose, isomaltose, or maltose are also accepted by MBT1, although with lower affinities. The MBT1 gene shows low and comparable expression levels in axenically grown C. graminicola and upon infection of maize leaves both during the initial biotrophic development of the fungus and during the subsequent necrotrophic phase. Despite these low levels of MBT1 expression, the MBT1 protein allows efficient growth of C. graminicola on melibiose as sole carbon source in axenic cultures. Although Δmbt1 mutants are unable to grow on melibiose, they do not show virulence defects on maize.