Secretome of Trichoderma Interacting With Maize Roots: Role in Induced Systemic Resistance
Secretome of Trichoderma Interacting With Maize Roots: Role in Induced Systemic Resistance
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DOI：
10.1074/mcp.m114.046607
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发表时间：
2015-04-01
影响因子：
7
通讯作者：
Horwitz, Benjamin A.
中科院分区：
文献类型：
--
作者：
Lamdan, Netta-Li;Shalaby, Samer;Horwitz, Benjamin A.
木霉（Trichoderma virens）是农业上用于对抗农作物病原菌的生物防治剂。除了直接的土壤真菌病原菌的真菌寄生，T. virens与根相互作用。这种相互作用诱导了系统抗性（ISR），从而减少了植物地上部分的病害。在真菌和植物之间导致ISR的分子对话中，由T. virens分泌的蛋白质提供信号。以前只有少数这样的蛋白质被描述过。为了研究其分泌组，本研究在单独培养或与玉米幼苗一起培养的水培系统中对其蛋白进行了表征，并结合对玉米叶片感染异养田鼠耳虫的ISR进行了生物测定。与玉米根共培养的玉米根分泌蛋白（Tv + M）比单独培养的玉米根分泌蛋白（Tv）具有更高的ISR活性。共鉴定出280种真菌蛋白，其中66种在Tv + M条件下丰度差异显著，其中32种在Tv + M条件下高，34种在Tv条件下高。在电视中发现的34个丰度较高且受根负调控的蛋白中，有13个是sscp（小的、分泌的、富含半胱氨酸的蛋白），已知在植物和真菌之间的分子对话中起重要作用。通过基因敲除研究了4种sscp在ISR中的作用。4个基因敲除系均表现出比WT更好的ISR活性，但不影响玉米根系的定殖。此外，与野生型相比，每个突变系的分泌蛋白片段都表现出更高的ISR活性。这些sscp显然是降低植物防御水平的负效应因子，可能对木霉对ISR的微调很重要。SSCPs在与植物根系相互作用中的下调意味着对木霉与植物共生及其诱导对病原体抗性的当前模型的修正。
Trichoderma virens is a biocontrol agent used in agriculture to antagonize pathogens of crop plants. In addition to direct mycoparasitism of soil-borne fungal pathogens, T. virens interacts with roots. This interaction induces systemic resistance (ISR), which reduces disease in above-ground parts of the plant. In the molecular dialog between fungus and plant leading to ISR, proteins secreted by T. virens provide signals. Only a few such proteins have been characterized previously. To study the secretome, proteins were characterized from hydroponic culture systems with T. virens alone or with maize seedlings, and combined with a bioassay for ISR in maize leaves infected by the pathogen Cochliobolus heterostrophus. The secreted protein fraction from coculture of maize roots and T. virens (Tv + M) was found to have a higher ISR activity than from T. virens grown alone (Tv). A total of 280 fungal proteins were identified, 66 showing significant differences in abundance between the two conditions: 32 were higher in Tv + M and 34 were higher in Tv. Among the 34 found in higher abundance in Tv and negatively regulated by roots were 13 SSCPs (small, secreted, cysteine rich proteins), known to be important in the molecular dialog between plants and fungi. The role of four SSCPs in ISR was studied by gene knockout. All four knockout lines showed better ISR activity than WT without affecting colonization of maize roots. Furthermore, the secreted protein fraction from each of the mutant lines showed improved ISR activity compared with WT. These SSCPs, apparently, act as negative effectors reducing the defense levels in the plant and may be important for the fine tuning of ISR by Trichoderma. The down-regulation of SSCPs in interaction with plant roots implies a revision of the current model for the Trichoderma-plant symbiosis and its induction of resistance to pathogens.