Colletotrichum gloeosporioides is a complex of species of phytopathogenic filamentous Ascomycota fungi of the Glomerellaceae family. They are responsible for the disease of the fruit known as anthracnose. This disease can affect any part of the plant and, in crops, is responsible for large economic losses worldwide.
The name Colletotrichum gloeosporioides designates the anamorphic (asexual reproduction) phase of the fungus, while the sexual or teleomorphic phase is called Glomerella cingulata. The anamorphic phase reproduces by means of conidiospores, while Glomerella cingulata does so by means of haploid ascospores.
Colletotrichum gloeosporioides laboratory culture Taken and edited from: Justraci.
Anthracnose attacks many wild and cultivated plants and causes spots or cankers on the stem and branches, spots on leaves and flowers, as well as fruit rot. The control of anthracnose can be done through crop management or through the addition of agrochemicals.
characteristics
The infective cycle
Colletotrichum gloeosporioides is an opportunistic pathogen that attacks injured plant tissues and is also an invader of dead material; in apparently healthy tissues of many plants it can be found both on the surface and in the interior of the plant. It can also be found in a quiescent state.
Penetration and colonization of the host by Colletotrichum gloeosporioides can occur in two ways. In the first, the conidia germinate and form oppressors that facilitate entry through the cuticle and host cells; in the second case, penetration occurs through the stomata by means of infection vesicles and hyphae.
After infection, the fungus may initiate a subcuticular intramural hemibiotrophic or necrotrophic phase. The first is asymptomatic and in it the penetrating structures invade the cells of the epidermis of the host and the primary hyphae produce infection vesicles inside the cells of the epidermis and the mesophyll.
This phase is followed by the necrotrophic phase, in which secondary hyphae will invade the interior of infected cells and neighboring cells, secreting enzymes that kill them.
In the intramural subcuticular necrotrophic phase, on the other hand, the fungus will grow under the cuticle within the periclinal and anti-canal walls of the epidermal cells, without penetrating the protoplasm. Subsequently, the hyphae initiate the destruction of the colonized tissues.
Reproduction
Reproduction can occur in the infected plant or in plant remains and can be asexual or sexual, but it is fundamentally associated with infection, especially in the asexual (anamorphic) form. The formation of the acervuli is associated with the appearance of the symptoms of the disease.
Sexual reproduction is poorly understood in this species, but in culture it has shown that perithecia (sexual fruiting bodies) form rapidly. These contain the asci that the haploid ascospores will produce.
When environmental conditions are favorable for the formation of perithecia, the release of ascospores is induced, which infect the neighboring tissues of the plant.
Ascospores germinate and infect plant tissues. The hyphae in these areas will develop acervules, which will produce masses of conidia in the conidiophores.
The conidia are spread by rain splashes or by the breeze to healthy leaves, young fruits or buds. Environmental conditions, as well as host senescence, can induce a new development of the sexual stage to restart the life cycle.
Anthracnose caused by Colletotrichum gloeosporioides on mangoes. Taken and edited from: Knowledge Center.
Chemical control
The chemical control of Colletotrichum gloeosporioides is carried out by means of fungicides that can be applied in spray, both in the pre and post-harvest period. The use of this type of control, applied in orchards at intervals of 2 to 4 weeks, has been shown to be effective in controlling the pathogen.
Postharvest control can also use immersion in fungicide, in addition to spray. This method is the most used for postharvest control of anthracnose in fruits and crops that are shipped by sea.
Fungicides used to control Colletotrichum gloeosporioides include copper hydroxide and copper sulfate, as well as prochloraz and azoxystrobin. The latter can inhibit or suppress the mycelial growth of the fungus. The alternate use of funchloraz and amistar has also been effective.
References
- C. Lyre. Colletotrichum: characteristics, taxonomy, morphology. Recovered from lifeder.com
- DD de Silva, PW Crous, PK Ades, KD Hyde & P.WJ Taylor (2017). Life styles of Colletotrichum species and implications for plant biosecurity. Fungal Biology Reviews.
- G. Sharma & BD Shenoy (2016). Colletotrichum systematics: Past, present and prospects. Mycosphere.
- M. Sharma & S. Kulshrestha (2015). Colletotrichum gloeosporioides: An anthracnose causing pathogen of fruits and vegetables. Biosciences Biotechnology Research Asia.
- Colletotrichum gloeosporioides. Recovered from wiki.bugwood.org.
- IA Quiroga. Anthracnose, a limiting disease for papaya production. Recovered from croplifela.org.