Colletotrichum higginsianum is a hemibiotrophic ascomycetous fungus that causes economically important anthracnose diseases on numerous monocot and dicot crops worldwide. As a model pathosystem, the Colletotrichum–Arabidopsis interaction has the significant advantage that both organisms can be manipulated genetically. The goal of this review is to provide an overview of the system and to point out recent significant studies that update our understanding of the pathogenesis of C. higginsianum and resistance mechanisms of Arabidopsis against this hemibiotrophic fungus. The genome sequence of C. higginsianum has provided insights into how genome structure and pathogen genetic variability has been shaped by transposable elements, and allows systematic approaches to longstanding areas of investigation, including infection structure differentiation and fungal–plant interactions. The Arabidopsis-Colletotrichum pathosystem provides an integrated system, with extensive information on the host plant and availability of genomes for both partners, to illustrate many of the important concepts governing fungal–plant interactions, and to serve as an excellent starting point for broad perspectives into issues in plant pathology.

Tea-oil tree (Camellia oleifera Abel) is an important edible oil woody plant with a planting area over 3,800,000 hectares in southern China. Anthracnose is a serious disease of tea-oil tree in southern China, causing severe economic losses and posing a huge threat to the Ca. oleifera industry. Based on recent developments in the classification of Colletotrichum species, the objective of this study was to identify Colletotrichum species associated with tea-oil tree and examine their pathogenicity on leaves and fruits of Ca. oleifera. In total, 232 isolates were obtained from Ca. oleifera leaves and fruits with anthracnose symptoms. These isolates were further characterized based on morphology and multilocus phylogenetic analyses using partial DNA sequences at the ribosomal internal transcribed spacer regions and β-tubulin, actin, calmodulin, glyceraldehyde-3-phosphate dehydrogenase, and chitin synthase-encoding genes. The fungal isolates belong to five species: C. camelliae, C. fructicola, C. siamense, C. aenigma, and C. gloeosporioides. C. camelliae was the most predominant and widely distributed species on fruits of Ca. oleifera (91.4%), followed by C. fructicola (6.3%). However, C. fructicola was common and widely distributed species on leaves (75.9%), followed by C. camelliae (17.2%). There was no evidence of geographical specialization of the different species. Pathogenicity assays showed that all tested isolates, including 20 of C. camelliae, 11 of C. fructicola, four of C. siamense, two of C. aenigma, and one of C. gloeosporioides, were pathogenic to leaves and fruits of Ca. oleifera. Among the five species, C. camelliae species showed strong pathogenicity on both leaves and fruits of Ca. oleifera, and C. fructicola, C. siamense, C. aenigma, and C. gloeosporioides all showed weak pathogenicity on both leaves and fruits. No relationship was found between origin of isolates and their virulence. This is the first description of C. camelliae, C. fructicola, C. siamense, and C. gloeosporioides from the fruits of Ca. oleifera in China.

Serine protease subtilase, found widely in both eukaryotes and prokaryotes, participates in various biological processes. However, how fungal subtilase regulates plant immunity is a major concern. Here, we identified a secreted fungal subtilase, UvPr1a, from the rice false smut (RFS) fungus Ustilaginoidea virens. We characterized UvPr1a as a virulence effector localized to the plant cytoplasm that inhibits plant cell death induced by Bax. Heterologous expression of UvPr1a in rice (Oryza sativa) enhanced plant susceptibility to rice pathogens. UvPr1a interacted with the important rice protein SUPPRESSOR OF G2 ALLELE OF skp1 (OsSGT1), a positive regulator of innate immunity against multiple rice pathogens, degrading OsSGT1 in a protease activity-dependent manner. Furthermore, host-induced gene silencing of UvPr1a compromised disease resistance of rice plants. Our work reveals a previously uncharacterized fungal virulence strategy in which a fungal pathogen secretes a subtilase to interfere with rice immunity through degradation of OsSGT1, thereby promoting infection. These genetic resources provide tools for introducing RFS resistance and further our understanding of plant–pathogen interactions.