Yan Tiantian, Zhou Xiaofan, Li Jieling, Li Guanjun, Zhao Yali, Wang Haojie, Li Huaping, Nie Yanfang, Li Yunfeng
College of Materials and Energy, South China Agricultural University, Guangzhou, China.
Guangdong Province Key Laboratory of Microbial Signals and Disease Control, College of Plant Protection, South China Agricultural University, Guangzhou, China.
Front Microbiol. 2022 Aug 30;13:1001540. doi: 10.3389/fmicb.2022.1001540. eCollection 2022.
f. sp. tropical race 4 (Foc TR4) is an important soilborne fungal pathogen that causes the most devastating banana disease. Effectors secreted by microbes contribute to pathogen virulence on host plants in plant-microbe interactions. However, functions of Foc TR4 effectors remain largely unexplored. In this study, we characterized a novel cupin_1 domain-containing protein (FoCupin1) from Foc TR4. Sequence analysis indicated that the homologous proteins of FoCupin1 in phytopathogenic fungi were evolutionarily conserved. Furthermore, FoCupin1 could suppress BAX-mediated cell death and significantly downregulate the expression of defense-related genes in tobacco by using the -mediated transient expression system. was highly induced in the early stage of Foc TR4 infection. The deletion of gene did not affect Foc TR4 growth and conidiation. However, deletion significantly reduced Foc TR4 virulence on banana plants, which was further confirmed by biomass assay. The expression of the defense-related genes in banana was significantly induced after inoculation with mutants. These results collectively indicate is a putative effector protein that plays an essential role in Foc TR4 pathogenicity. These findings suggest a novel role for cupin_1 domain-containing proteins and deepen our understanding of effector-mediated Foc TR4 pathogenesis.
尖孢镰刀菌古巴专化型热带4号小种（Foc TR4）是一种重要的土传真菌病原体，可引发最具毁灭性的香蕉病害。在植物与微生物的相互作用中，微生物分泌的效应子有助于病原体对宿主植物的致病性。然而，Foc TR4效应子的功能在很大程度上仍未得到探索。在本研究中，我们对来自Foc TR4的一种含有新型cupin_1结构域的蛋白（FoCupin1）进行了表征。序列分析表明，植物病原真菌中FoCupin1的同源蛋白在进化上是保守的。此外，通过农杆菌介导的瞬时表达系统，FoCupin1可以抑制BAX介导的细胞死亡，并显著下调烟草中防御相关基因的表达。FoCupin1在Foc TR4感染的早期阶段被高度诱导。FoCupin1基因的缺失不影响Foc TR4的生长和产孢。然而，FoCupin1基因的缺失显著降低了Foc TR4对香蕉植株的致病性，生物量测定进一步证实了这一点。接种FoCupin1突变体后，香蕉中防御相关基因的表达被显著诱导。这些结果共同表明FoCupin1是一种推定的效应子蛋白，在Foc TR4的致病性中起重要作用。这些发现揭示了含cupin_1结构域蛋白的新作用，并加深了我们对效应子介导的Foc TR4致病机制的理解。
