Islam Kazi T, Bond Jason P, Fakhoury Ahmad M
Department of Plant, Soil and Agriculture Systems, Southern Illinois University, Carbondale, IL, 62901, USA.
Donald Danforth Plant Science Center, St Louis, MO, 63132, USA.
Appl Microbiol Biotechnol. 2017 Aug;101(16):6431-6445. doi: 10.1007/s00253-017-8387-1. Epub 2017 Jun 22.
The soil-borne fungus Fusarium virguliforme causes sudden death syndrome (SDS), one of the most devastating diseases of soybean in North and South America. Despite the importance of SDS, a clear understanding of the fungal pathogenicity factors that affect the development of this disease is still lacking. We have identified FvSTR1, a F. virguliforme gene, which encodes a protein similar to a family of striatin proteins previously reported to regulate signalling pathways, cell differentiation, conidiation, sexual development, and virulence in filamentous fungi. Striatins are multi-domain proteins that serve as scaffolding units in the striatin-interacting phosphatase and kinase (STRIPAK) complex in fungi and animals. To address the function of a striatin homologue in F. virguliforme, FvSTR1 was disrupted and functionally characterized using a gene knock out strategy. The resulting Fvstr1 mutants were largely impaired in conidiation and pigmentation, and displayed defective conidia and conidiophore morphology compared to the wild-type and ectopic transformants. Greenhouse virulence assays revealed that the disruption of FvSTR1 resulted in complete loss of virulence in F. virguliforme. Microtome studies using fluorescence microscopy showed that the Fvstr1 mutants were defective in their ability to colonize the vascular system. The Fvstr1 mutants also showed a reduced transcript level of genes involved in asexual reproduction and in the production of secondary metabolites. These results suggest that FvSTR1 has a critical role in asexual development and virulence in F. virguliforme.
土传真菌镰刀菌（Fusarium virguliforme）可引发猝死综合征（SDS），这是北美和南美大豆最具毁灭性的病害之一。尽管SDS很重要，但目前仍缺乏对影响该病害发展的真菌致病因子的清晰认识。我们鉴定出了FvSTR1，这是一种镰刀菌基因，它编码的蛋白质类似于先前报道的在丝状真菌中调节信号通路、细胞分化、分生孢子形成、有性发育和毒力的striatin蛋白家族。Striatins是多结构域蛋白，在真菌和动物的striatin相互作用磷酸酶和激酶（STRIPAK）复合物中作为支架单元。为了研究镰刀菌中striatin同源物的功能，采用基因敲除策略对FvSTR1进行了破坏并进行功能表征。与野生型和异位转化体相比，产生的Fvstr1突变体在分生孢子形成和色素沉着方面有很大缺陷，并且分生孢子和分生孢子梗形态存在缺陷。温室毒力试验表明，FvSTR1的破坏导致镰刀菌完全丧失毒力。使用荧光显微镜的切片研究表明，Fvstr1突变体在定殖于维管系统的能力方面存在缺陷。Fvstr1突变体还显示出参与无性繁殖和次生代谢产物产生的基因转录水平降低。这些结果表明，FvSTR1在镰刀菌的无性发育和毒力中起关键作用。
