Home • Glomerella acutata (Colletotrichum fiorinae MH 18) v1.0
Conidia of Glomerella acutata
Conidia of Glomerella acutata (Damm et al, 2012. Studies in Mycology. 73:37-113)

Within the framework of the CSP project 'Metatranscriptomics of Forest Soil Ecosystems', we are aiming to explore the interaction of forest trees with communities of soil fungi, including ectomycorrhizal symbionts that dramatically affect bioenergy-relevant plant growth, and saprotrophic soil fungi impacting carbon sequestration in forests. We are sequencing the metatranscriptome of soil fungi in ecosystems representative of major Earth ecosystems, the boreal, temperate and mediterranean forests. We are also sequencing the genome of the most abundant fungal species harvested on studied sites to serve as the foundation for a reference database for metagenomics of fungi and for a comprehensive survey of the potential soil fungal metabolome.

Glomerella acutata (= Colletotrichum fiorinae MH 18)

The genus Glomerella (phylum Ascomycota, subphylum Sordariomycetes, order Glomerelalles) is a group of mostly pathogenic plant-associated fungi that occur on a broad range of host species. During the asexual (mitotic) phase of their life cycle, Glomerella species produce acervuli within the host tissue containing curved and elongated conidia organized in phialides. Sexual reproduction, which is more rarely observed, results in formation of dark, long-necked perithecia with clavate asci. Both homothallic and heterothallic strains have been observed. Because this group includes many pathogenic species, taxonomists have suggested that the more widely used asexual name Colletotrichum be maintained as the correct name for this genus.  

Most species within this genus are plant pathogens causing anthracnose-like symptoms (sunken necrotic lesions) in agricultural and horticultural hosts, grasses and forest trees. Other symptoms, such as canker, dieback and rots have also been observed. In addition, members of this genus have been frequently isolated as asymptomatic endophytes.  Host infection strategies are well studied for certain pathosystems, and they start with conidia germination and penetration of host tissue through formation of appressoria, or plant colonization through stomata. After penetration, different species can establish nectrotrophic or hemibiotrophic infections, or grow as endophytes, in the intercellular space of the host tissue. Molecular systematics studies reveal that there is considerable genetic variation within various species complexes in Glomerella/Colletotrichum, which vary in diversity of host they infect, and their mechanisms of infection. 

Glomerella acutata is the most common and widely known species of the genus, originally described from a range of host species. Morphologically it is characterized by formation of fusiform conidia with acute ends, produced both in pigmented acervuli in the host and in aerial mycelia in culture. G. acutata represents a morphologically and phylogenetically diverse species complex; 31 species were recently recognized within this group based on six-gene phylogeny. G. acutata is regarded as a complex species which is evolving rapidly and can adapt to many different host species and lifestyles within the host. This taxon is the most commonly isolated (and one of the most abundant sequence-type) group from asymptomatic and symptomatic first year tree seedlings from Duke Forest, North Carolina.

References

1. Cannon PF, Damm U, Johnston PR, Weir BS. 2012. Colletotrichum – current status and future directions. Studies in Mycology. 73:181-213.

2. Damm U, Cannon PF, Woudenberg JHC, Crous PW. 2012. The Colletotrichum acutatum species complex. Studies in Mycology. 73:37-113.

3. Gazis R, Rehner S, Chaverri P. 2011. Species delimitation in fungal endophyte diversity studies and its implications in ecological and biogeographic inferences. Mol. Ecol. 20:3001-3013.

4. Hersh MH, Vilgalys R, Clark JS. 2012. Evaluating the impacts of multiple generalist fungal pathogens on temperate tree seedling survival. Ecology. 93:511-520. 

5. Weir BS, Johnston PR, Damm U. 2012. The Colletotrichum gloeosporioides species complex. Studies in Mycology. 73:115-180. 

6. Zhang N, Castlebury LA, Miller AN, Huhndorf SM, Schoch CL, Seifert KA, Rossman AY, Rogers JD, Kohlmeyer J, Volkmann-Kohlmeyer B, Sung G. November/December 2006. An overview of the systematics of the Sordariomycetes based on a four-gene phylogeny. Mycologia. 98:1076-1087.