Endophytic, saprobic, and pathogenic fungi have evolved elaborate strategies to obtain nutrients from plants. Among the diverse plant-fungi interactions, the most crucial event is the attachment and penetration of the plant surface. Appressoria, specialized infection structures, have been evolved to facilitate this purpose. In this review, we describe the diversity of these appressoria and classify them into two main groups: single-celled appressoria (proto-appressoria, hyaline appressoria, melanized (dark) appressoria) and compound appressoria. The ultrastructure of appressoria, their initiation, their formation, and their function in fungi are discussed. We reviewed the molecular mechanisms regulating the formation and function of appressoria, their strategies to evade host defenses, and the related genomics and transcriptomics. The current review provides a foundation for comprehensive studies regarding their evolution and diversity in different fungal groups.

Fungi have evolved diverse strategies to acquire nutrients as endophytes, saprobes, symbionts, or pathogens. Appressoria have been intensively studied due to their importance in attaching and breaching the host surface. These specialized infection structures have evolved into various morpho-types: proto-appressoria, hyaline appressoria, melanized (dark) appressoria, and compound appressoria. In this review, we discuss the differences in the formation, differentiation, and function of appressoria among fungi with diverse life strategies. Using DNA sequence information, LSU, 5.8S, SSU and rpb2 gene fragments, we reconstructed the ancestral states for appressorial types in the main phyla of fungi and fungus-like organisms and found that the hyaline appressoria was the most ancestral form. Our analysis estimated proto-appressoria diversification during the Mesozoic period (92–239 million years ago), however, its origin remains inconclusive. Our data suggest that these hyaline appressoria diversified into melanized or compound appressoria, with evidence of adaptive radiation.

This study aimed to identify fungal species associated with trunk diseases of sweet cherries (Prunus avium) in several commercial cherry orchards in Beijing, Guizhou and Shandong provinces, China. In total, eighteen fungal strains that fitted well into the species concept of Diaporthe were isolated. Based on both morphological and multi-locus phylogenetic analyses of internal transcribed spacer region (ITS), beta-tubulin (tub-2), calmodulin (Cal) and translation elongation factor 1-α (tef1–α) sequencing data, fourteen isolates were identified as Diaporthe eres, while four isolates were classified as D. hongkongensis. Here, we report D. hongkongensis causing sweet cherry branch dieback disease and, further, we confirmed the host association of D. eres with sweet cherries in China. A pathogenicity assay revealed the ability of both D. eres and D. hongkongensis to cause shoot necrosis and stem lesions on Prunus avium cv. ‘Brooks’ (mean lesion lengths of 1.86 cm and 1.56 cm, respectively). The optimal temperature for the growth of both Diaporthe species was tested. The optimal growth temperature for D. hongkongensis was 30 °C, and the 25–28 °C temperatures were the most favorable for the growth of D. eres strains. This research advances the understanding of fungal trunk diseases in fruit crops, particularly gummosis and branch dieback disease in Chinese cherry orchards, and will aid growers in making decisions about cultural practices and disease management.

The black-foot disease of grapevine is one of the most destructive diseases in viticulture and it is caused by a complex of soil-borne fungi. This study aimed to identify the species associated with black-foot disease in young grapevines in vineyards of China. Fungal isolates were identified as Campylocarpon fasciculare, based on both morphological and multi-locus phylogenetic analysis of ITS, tef1–α and ß-tubulin sequence data. For the first time in China, we report Campylocarpon fasciculare associated with symptomatic young grapevines. Koch’s postulates were performed on Vitis vinifera cv. Summer Black (SB) in a greenhouse and to confirm the pathogenicity on grapevines. This work improves the knowledge of black-foot disease in Chinese vineyards and will be helpful to growers in their decisions regarding vinicultural practices, planting and disease management.

Sunflower (Helianthus annuus L. family Asteraceae) is grown as an important agricultural crop worldwide in temperate and sub-tropical climates. Head rot symptoms were found on cultivated sunflowers...

Peach (Prunus persica) is widely cultivated in China, but fungal diseases, particularly Cytospora canker, significantly impact tree health, reducing fruit yield and economic value. This disease mainly weakens tree branches and trunks, sometimes leading to tree death. There are no updated studies on the diversity of Cytospora species associated with peach Cytospora canker in northern China. To determine the Cytospora species associated with this disease, we surveyed five provinces from 2022 to 2023, collecting 72 disease samples with symptoms including branches with black fruiting bodies, cankers, cracking, dieback, and gummosis. Through morphology and multi-loci phylogeny, 127 isolates were identified into four known (C. ailanthicola, C. erumpens, C. leucostoma, and C. leucosperma) and two previously undescribed species (C. gansuensis sp. nov. and C. qinanensis sp. nov.). Cytospora leucostoma (73.60%) was the most abundant. Pathogenicity tests indicated that except for C. ailanthicola, all other species were pathogenic to peach, with C. erumpens being the most aggressive. This study is the first to report the novel host association of C. erumpens on peaches globally and represents the first comprehensive investigation of Cytospora species associated with canker diseases in the main peach production area in northern China, offering a foundation for developing effective disease management strategies.