A Gin4-Like Protein Kinase GIL1 Involvement in Hyphal Growth, Asexual Development, and Pathogenesis in Fusarium graminearum

Abstract

<i>Fusarium graminearum</i> is the main causal agent of <i>Fusarium</i> head blight (FHB) on wheat and barley. In a previous study, a GIN4-like protein kinase gene, <i>GIL1</i>, was found to be important for plant infection and sexual reproduction. In this study we further characterized the functions of <i>GIL1</i> kinase in different developmental processes. The Δ<i>gil1</i> mutants were reduced in growth, conidiation, and virulence, and formed whitish and compact colonies. Although phialide formation was rarely observed in the mutants, deletion of <i>GIL1</i> resulted in increased hyphal branching and increased tolerance to cell wall and cell membrane stresses. The Δ<i>gil1</i> mutants produced straight, elongated conidia lacking of distinct foot cells and being delayed in germination. Compared with the wild type, some compartments in the vegetative hyphae of Δ<i>gil1</i> mutants had longer septal distances and increased number of nuclei, suggesting <i>GIL1</i> is related to cytokinesis and septation. Localization of the GIL1-GFP fusion proteins to the septum and hyphal branching and fusion sites further supported its roles in septation and branching. Overall, our results indicate that <i>GIL1</i> plays a role in vegetative growth and plant infection in <i>F. graminearum</i>, and is involved in septation and hyphal branching.