Ste2 receptor-mediated chemotropism of Fusarium graminearum contributes to its pathogenicity against wheat

Abstract

Fusarium Head Blight of wheat, caused by the filamentous fungus Fusarium graminearum, leads to devastating global food shortages and economic losses. While many studies have addressed the responses of both wheat and F. graminearum during their interaction, the possibility of fungal chemotropic sensing enabling pathogenicity remains unexplored. Based on recent findings linking the pheromone-sensing G-protein-coupled receptor Ste2 to host-directed chemotropism in Fusarium oxysporum, we investigated the role of the Ste2 receptor and its downstream signaling pathways in mediating chemotropism of F. graminearum. Interestingly, a chemotropic response of growing hyphae towards catalytically active Triticum aestivum 'Roblin' cultivar secreted peroxidases was detected, with deletion of STE2 in F. graminearum leading to loss of the observed response. At the same time, deletion of STE2 significantly decreased infection on germinating wheat coleoptiles, highlighting an association between Ste2, chemotropism and infection by F. graminearum. Further characterization revealed that the peroxidase-directed chemotropism is associated with stimulation of the fungal cell wall integrity mitogen-activated protein kinase signaling cascade. Altogether, this study demonstrates conservation of Ste2-mediated chemotropism by Fusarium species, and its important role in mediating pathogenicity.

Components of TOR and MAP kinase signaling control chemotropism and pathogenicity in the fungal pathogen Verticillium dahliae

“…Our experiments revealed that V. dahliae germlings can readily sense and re-orient growth of their hyphal tips towards different carbon and nitrogen sources, similar to what has been previously reported in F. oxysporum and F. graminearum (Sridhar et al, 2020; Turrà et al, 2015). Nitrogen availability is particularly important for plant pathogenicity (Deng et al, 2015), and the ability of the pathogen to sense and reach suitable nitrogen sources is likely to be important for successful host invasion (Thalineau et al, 2016).…”

“…Since the necessary resources for their survival are heterogeneously distributed in their habitats, fungi have evolved mechanisms for sensing the environment and responding by directed growth (Brand and Gow, 2009; Leeder et al, 2011). This results from dynamic re-orientation of hyphal growth towards or away from stimuli such as nutrients, toxic substances, other individuals (e.g., during mating and vegetative fusion), and host organisms (Lombardi et al, 2018; Moreno-Ruiz et al, 2020; Sridhar et al, 2020; Turrà et al, 2015; Vangalis et al, 2021a). In the case of fungal pathogens, chemotropic sensing and growth play prominent roles during host-pathogen interactions (Turrà et al, 2016).…”

Kinesin-8-specific loop-2 controls the dual activities of the motor domain according to tubulin protofilament shape

“…Fractions were visualized by SDS-PAGE stained with Coomassie brilliant blue R-250. For specific samples, immunoblotting using HRP-conjugated anti-His antibody (Abcam, ab1187) was performed based on an established protocol 66 . Following SDS-PAGE of fractions diluted 1:20, a wet electroblot at 400 mA for 2 h was used to transfer proteins to a PVDF membrane.…”

Kinesin-8-specific loop-2 controls the dual activities of the motor domain according to tubulin protofilament shape

“…Fractions were visualized by SDS-PAGE stained with Coomassie brilliant blue R-250. For specific samples, immunoblotting using HRP-conjugated anti-His antibody (Abcam, ab1187) was performed based on an established protocol 45 . Following SDS-PAGE of fractions diluted 1:20, a wet electroblot at 400 mA for 2 hours was used to transfer proteins to a PVDF membrane.…”