Wenjie Xu

The phytopathogenic fungus Colletotrichum scovillei causes a destructive anthracnose on pepper fruit worldwide. Conidiation plays an essential role in the dissemination of pathogenic fungi, yet the regulatory mechanisms underlying this process remain largely unknown. In this study, a pheromone-regulated membrane protein 10 (PRM10) was identified in C. scovillei, whose function has not been characterized in fungal plant pathogens previously. The targeted gene deletion mutant (ΔCsprm10) was normal in plant infection but showed a decrease in surface hydrophobicity compared to the wild-type strain. Notably, ΔCsprm10 was completely defective in conidiation. A microscopic observation further confirmed that ΔCsprm10 failed to form conidiophores, suggesting that CsPRM10 plays an essential role in the conidiation of C. scovillei by regulating conidiophore development. The transcriptomic analysis indicated that the loss of CsPRM10 caused differential expressions of genes related to membrane-associated processes and nuclear functions. Taken together, these findings suggest that CsPRM10 acts as a novel regulator of conidiation in C. scovillei and provide new insights into the molecular basis of fungal asexual development.

Fusarium head blight caused by Fusarium graminearum is a serious fungal disease on wheat and maize worldwide, resulting in a significant economic loss. DUG3-mediated glutathione utilization has been revealed to play important roles in fungal differentiation, metabolism, stress adaptation, and plant infection. However, functional roles of the DUG3 homolog in F. graminearum remain uncharacterized. In the present study, FgDUG3 was knocked-out via homologous recombination to investigate functions of this gene. The deletion mutant (ΔFgDUG3) was normal in mycelial growth, but showed impairments in conidiation, conidial germination, and plant infection, compared to the wild-type strain. The defects of ΔFgDUG3 were recovered in the complemented strain (ΔFgDUG3-C). Transcriptomic analysis revealed that deletion of FgDUG3 caused significantly differential expression of genes, mainly related to metabolism, catabolism, cellular structure organization, and signal transduction. Taken together, these results suggest that FgDUG3 plays important roles in the differentiation and pathogenicity of F. graminearum.

Fusarium Head Blight (FHB, scab) is a destructive fungal disease that causes extensive yield and quality losses in wheat and other small cereals. Biological control of FHB is considered to be an alternative disease management strategy that is environmentally benign, durable, and compatible with other control measures. In this study, to screen antagonistic bacteria with the potential to manage FHB, 113 endophytes were isolated from the stems, leaves, panicles, and roots of wheat. Among them, six strains appeared to effectively inhibit Fusarium graminearum growth and one isolate, XS-2, showed a highly antagonistic effect against FHB. An in vitro antagonistic test of XS-2 on wheat heads confirmed that XS-2 could suppress the disease severity of FHB. The 16S rDNA sequence analysis revealed that XS-2 is a strain of Bacillus amyloliquefaciens. Antagonistic spectrum analyses showed that XS-2 had antagonistic effects against two and four types of cotton and fruit tree pathogens, respectively. The fermentation condition assays showed that glucose and peptone are the most suitable nutrient sources for XS-2, and that the optimal pH value and temperature for fermentation were 7.4 and 28 °C, respectively. Our study indicates that XS-2 has a good antagonistic effect on FHB and lays a theoretical foundation for the application of the strain as a biological agent in the field to control FHB.