The chitin synthase FgChs2 and other FgChss co-regulate vegetative development and virulence in F. graminearum

Abstract

Fusarium graminearum contains eight chitin synthase (Chs) genes belonging to seven classes. Previous studies have found that deletion of FgChs3b is lethal to F. graminearum, and deletion of FgChs1, FgChs2, FgChs7 and FgChs5 caused diverse defects in chitin content, mycelial growth, conidiation, virulence or stress responses. However, little is known about the functional relationships among these FgChss. In this study, FgChs2 deletion mutant ΔFgChs2 exhibited reduced mycelial growth and virulence as reported previously. In addition, we found that the mutant produced thickened and “wavy” septa. Quantitative real-time PCR (qRT-PCR) assays showed that the expression levels of FgChs1, FgChs3a, FgChs4, FgChs7, FgChs5 and FgChs6 in ΔFgChs2 were significantly higher than those in the wild type. Therefore, we generated six double deletion mutants of FgChs2 and each of the above six FgChss, and found that FgChs2 shares a function with FgChs1 in regulating mycelial growth, and co-regulates conidiation with FgChs1, FgChs4, FgChs7 and FgChs5. Furthermore, FgChs2 and other six FgChss have overlapped functions in virulence, DON production and septum formation. Taken together, these results indicate that although each chitin synthase of F. graminearum plays certain roles, FgChss may co-regualte various cellular processes in F. graminearum.

Chitin synthase is involved in vegetative growth, asexual reproduction and pathogenesis of Phytophthora capsici and Phytophthora sojae

“…Our results indicated that PcCHS and PsCHS1 , but not PsCHS2 , have functions in regulating mycelial growth, sporangial production and zoospore release, as well as zoospore germination and hyphal branch formation during early infection. As is true of certain fungal CHS genes (Kong et al ., ; Cheng et al ., ; Liu et al ., ), we suggest that PcCHS and PsCHS1 play critical roles during normal vegetative growth, propagation and pathogenicity in P. capsici and P. sojae . Although vegetative growth and reproduction were retarded in the Δ PcCHS and Δ PsCHS1 mutants, we found no obvious morphological hyphal abnormality (swelling and/or distortion) under the microscope.…”

“…In Fusarium graminearum , which contains eight CHS genes, deletion of FgCHS3b is lethal to the fungus, whereas deletion of FgCHS1 , FgCHS2 , FgCHS7 or FgCHS5 variously affects chitin content, mycelial growth, conidiation, virulence or stress responses. However, deletion of FgCHS3a , FgCHS4 or FgCHS6 did not seem to have any effects (Xu et al ., ; Cheng et al ., ; Liu et al ., ).…”

FgAP‐2 complex is essential for pathogenicity and polarised growth and regulates the apical localisation of membrane lipid flippases inFusarium graminearum

“…Because DON plays an important role in the extension of F . graminearum inside the hosts (Liu et al, ), we reasoned the inability of the FgAP‐2 deletion mutants to cause severe disease symptoms in the host is largely due to their slow growths.…”

Cell Wall Biogenesis Protein Phosphatase CrSsd1 Is Required for Conidiation, Cell Wall Integrity, and Mycoparasitism in Clonostachys rosea

“…Normal mycelial growth is crucial to ensure fungal vitality and other activities (Cota et al, 2008;Liu et al, 2016).…”

“…Normal mycelial growth is crucial to ensure fungal vitality and other activities ( Cota et al, 2008 ; Liu et al, 2016 ). In our current study, ΔCrSsd1 deletion mutants exhibited reduced hyphal growth, suggesting diverse functions for CrSsd1 in different fungal pathogens.…”