Actin‐bundling protein fimbrin regulates pathogenicity via organizing F‐actin dynamics during appressorium development in Colletotrichum gloeosporioides

Abstract

Anthracnose caused by Colletotrichum gloeosporioides leads to serious economic loss to rubber tree yield and other tropical crops. The appressorium, a specialized dome-shaped infection structure, plays a crucial role in the pathogenesis of C. gloeosporioides. However, the mechanism of how actin cytoskeleton dynamics regulate appressorium formation and penetration remains poorly defined in C. gloeosporioides.In this study, an actin cross-linking protein fimbrin homologue (CgFim1) was identified in C. gloeosporioides, and the knockout of CgFim1 led to impairment in vegetative growth, conidiation, and pathogenicity. We then investigated the roles of CgFim1 in the dynamic organization of the actin cytoskeleton. We observed that actin patches and cables localized at the apical and subapical regions of the hyphal tip, and showed a disc-to-ring dynamic around the pore during appressorium development. CgFim1 showed a similar distribution pattern to the actin cytoskeleton. Moreover, knockout of CgFim1 affected the polarity of the actin cytoskeleton in the hyphal tip and disrupted the actin dynamics and ring structure formation in the appressorium, which prevented polar growth and appressorium development. The CgFim1 mutant also interfered with the septin structure formation. This caused defects in pore wall overlay formation, pore contraction, and the extension of the penetration peg. These results reveal the mechanism by which CgFim1 regulates the growth and pathogenicity of C. gloeosporioides by organizing the actin cytoskeleton.

Plant infection by the necrotrophic fungusBotrytisrequires actin-dependent generation of high invasive turgor pressure

“…4). Recently, this has been also reported for Phytophthora and Colletotrichum 11,16,25 , indicating a conserved role of actin for appressorium development. However, pharmacological interference of actin polymerization by LatB did not only affect the Botrytis appressorium but directly impacted penetration as well as virulence.…”

Advances in understanding the mechanism of resistance to anthracnose and induced defence response in tea plants

“…Moreover, an actin cross‐linking protein fimbrin homologue ( CgFim1 ) is required for the formation of the pore wall overlay, pore contraction, and the extension of a penetration peg, and is also involved in the regulation of the actin cytoskeleton in the hypha and appressorium. CgFim1 ‐mediated F‐actin interacts with septin to regulate appressorium development in C. gloeosporioides (Zhang et al, 2022) (Figure 1). These protein‐encoding genes play important roles in conidial germination and appressorium formation during colonization of C. gloeosporioides in host tissue.…”

Appressoria—Small but Incredibly Powerful Structures in Plant–Pathogen Interactions

“…CgFim1, an actin cross-linking protein fimbrin homolog, was identified and characterized by its physiological functions in C. gloeosporioides. The deletion of CgFim1 prevented polar growth and appressorium development due to disrupting the actin dynamics and ring structure formation in the appressorium as well as affecting the polarity of the actin cytoskeleton in the hyphal tip [84]. Arginine, one of the several types of amino acids, is required for the biochemical and physiological functions of fungi.…”