Abstract：
Secreted common fungal extracellular membrane (CFEM) domain proteins have been implicated in multiple biological functions in fungi. However, it is still largely unknown whether the ferric iron (Fe3+), as an important trace element, was involved with the biological function of CFEM proteins. In this study, a new CFEM protein CgCsa, with high expression levels at the early inoculation stage on peppers by Colletotrichum gloeosporioides was investigated. Deletion of the targeted gene CgCsa revealed multiple biological roles in hyphal growth restriction, highly reduced conidial yield, delayed conidial germination, abnormal appressorium with elongated bud tubes, and significantly reduced virulence of C. gloeosporioides. Moreover, in CgCsa mutants, the expression levels of four cell wall synthesis-related genes were downregulated, and cell membrane permeability and electrical conductivity were increased. Compared to the wild-type, the CgCsa mutants downregulated expressions of iron transport-related genes, in addition, its three-dimensional structure was capable binding with iron. Increase in the Fe3+ concentration in the culture medium partially recovered the functions of ΔCgCsa mutant. This is probably the first report to show the association between CgCsa and iron homeostasis in C. gloeosporioides. The results suggest an alternative pathway for controlling plant fungal diseases by deplete their trace elements.
摘要：
分泌的常见真菌胞外膜（CFEM）结构域蛋白与真菌的多种生物学功能有关。然而,目前还不清楚三价铁(Fe3+)作为一种重要的微量元素，与CFEM蛋白的生物学功能有关。在这项研究中,一种新的CFEM蛋白CgCsa,研究了炭疽菌在辣椒早期接种阶段的高表达水平。目标基因CgCsa的缺失揭示了菌丝生长限制中的多种生物学作用，高度降低的分生孢子产量，延迟的分生孢子萌发，带有细长芽管的异常附着体，并显着降低了C.gloeosporioides的毒力。此外，在CgCsa突变体中，4种细胞壁合成相关基因的表达水平随着菌丝细胞壁通透性的增加而下调,这导致电导率增加。与野生型相比,CgCsa突变体下调铁转运相关基因的表达，此外,它的三维结构能够与铁结合。培养基中Fe3浓度的增加部分恢复了ΔCgCsa突变体的功能。这可能是第一份显示CgCsa与C.gloeosporioides中铁稳态之间关联的报告。结果表明，通过消耗其微量元素来控制植物真菌疾病的替代途径。
