The fungal UmSrt1 and maize ZmSUT1 sucrose transporters battle for plant sugar resources

作     者：Anke Wittek Ingo Dreyer Khaled A.S. Al-Rasheid Norbert Sauer Rainer Hedrich Dietmar Geiger 

作者机构：Institute for Molecular Plant Physiology and Biophysics Julius-von-Sachs-lnstitute Biocenter University of Wurzburg 97082 Wurzburg Germany Centro de Bioinformatica y Simulacion Molecular Facultad de Ingenieria Universidad de Talca Talca Chile College of Science King Saud University Riyadh 11451 Saudi Arabia Molecular Plant Physiology University Erlangen-Nurnberg 91058 Erlangen Germany 

出 版 物：《Journal of Integrative Plant Biology》 (植物学报（英文版）)

年 卷 期：2017年第59卷第6期

页      面：422-435页

核心收录：

学科分类：0710[理学-生物学] 09[农学] 0904[农学-植物保护] 0901[农学-作物学] 0703[理学-化学] 090401[农学-植物病理学] 0902[农学-园艺学] 090402[农学-农业昆虫与害虫防治] 

基　　金：supported by the Deutsche Forschungsgemeinschaft (DFG) within the Grant GE2195/1-1 supported by grants from the King Saud University supported by the FONDECYT grant N 1150054 from the Comisión Nacional Científicay Tecnológica of Chile 

主　　题：William J. Lucas, University of California, Davis, USAReceived Mar. 1, 2017 Accepted Mar. 10, 2017 Online on Mar. 15,2017 

摘      要：The biotrophic fungus Ustilago maydis causes corn smut disease, inducing tumor formation in its host Zea mays. Upon infection, the fungal hyphae invaginate the plasma membrane of infected maize ceils, establishing an interface where pathogen and host are separated only by their plasma membranes. At this interface the fungal and maize sucrose transporters, UmSrtl and ZmSUT1, compete for extracellular sucrose in the corn smut/maize pathos- ystem. Here we biophysically characterized ZmSUT1 and UmSrtl in Xenopus oocytes with respect to their voltage-, pH- and substrate-dependence and determined affinities toward protons and sucrose. In contrast to ZmSUT% UmSrtl has a high affinity for sucrose and is relatively pH- and voltage-independent. Using these quantitative parameters, we developed a mathematical model to simulate the competition for extracellular sucrose at the contact zone between the fungus and the host plant. This approach revealed that UmSrtl exploits the apoplastic sucrose resource, which forces the plant transporter into a sucrose export mode providing the fungus with sugar from the phloem. Importantly, the high sucrose concen- tration in the phloem appeared disadvantageous for the ZmSUT1 preventing sucrose recovery from the apoplastic space in the fungus/plant interface.