Wang Yuhua, Zhang Xinchun, Wang Tian, Zhou Siyu, Liang Xiaofei, Xie Changping, Kang Zhensheng, Chen Daipeng, Zheng Li
Key Laboratory of Green Prevention and Control of Tropical Plant Disease and Pests, Ministry of Education and School of Plant Protection, Hainan University, Haikou, China.
Environment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Sciences, Haikou, China.
Front Plant Sci. 2022 May 10;13:873451. doi: 10.3389/fpls.2022.873451. eCollection 2022.
Fusarium wilt of banana ( spp.), a typical vascular wilt disease caused by the soil-borne fungus, f. sp. race 4 (Foc4), seriously threatens banana production worldwide. Pathogens, including vascular wilt fungi, secrete small cysteine-rich proteins during colonization. Some of these proteins are required for pathogenicity. In this study, 106 small secretory proteins that contain a classic N-terminal signal peptide were identified using bioinformatic methods in Foc4. Among them, 11 proteins were selected to show transient expressions in tobacco. Interestingly, transient expression of FoSsp1 in tobacco, an uncharacterized protein (of 145 aa), induced necrotic cell death reactive oxygen burst, and callous deposition. Furthermore, the expression of in Foc4 wild type (WT) was up-regulated during the stage of banana roots colonization. A split-marker approach was used to knock out in the Foc4 WT strain. Compared with the WT, the deletion mutant was normal in growth rate but increased in conidiation and virulence. RT-qPCR analysis showed that the expression of four conidiation regulator genes in the deletion mutant was significantly decreased compared to the WT strain. In addition, the expression of four pathogenesis-related genes of bananas infected with deletion mutant was down-regulated in comparison with that of the WT. In summary, these results suggested that is a putative elicitor that negatively regulates conidiation and pathogenicity in Foc4.
香蕉枯萎病（尖孢镰刀菌香蕉专化型）是一种由土壤传播真菌尖孢镰刀菌古巴专化型4号生理小种（Foc4）引起的典型维管束枯萎病，严重威胁着全球香蕉生产。包括维管束枯萎真菌在内的病原体在定殖过程中会分泌富含半胱氨酸的小蛋白。其中一些蛋白是致病性所必需的。在本研究中，利用生物信息学方法在Foc4中鉴定出106个含有经典N端信号肽的小分泌蛋白。其中，选择了11个蛋白在烟草中进行瞬时表达。有趣的是，FoSsp1（一种145个氨基酸的未鉴定蛋白）在烟草中的瞬时表达诱导了坏死性细胞死亡、活性氧爆发和胼胝质沉积。此外，FoSsp1在Foc4野生型（WT）中的表达在香蕉根定殖阶段上调。采用裂合酶介导的方法在Foc4 WT菌株中敲除FoSsp1。与WT相比，缺失突变体在生长速率上正常，但分生孢子形成和毒力增加。RT-qPCR分析表明，与WT菌株相比，缺失突变体中四个分生孢子形成调节基因的表达显著降低。此外，与WT相比，感染缺失突变体的香蕉中四个病程相关基因的表达下调。总之，这些结果表明FoSsp1是一种推定的激发子，在Foc4中对分生孢子形成和致病性起负调控作用。
