Deceptive behaviour of Colletotrichum truncatum: strategic survival as an asymptomatic endophyte on non-host species

Abstract

Colletotrichum truncatum (syn. C. capsici), like many other members of the genus Colletotrichum, displays a highly developed infection mechanism against a number of agriculturally important crops. Among many survival strategies, C. truncatum is well known for its wide host range and high pathogenicity on several major crop species. Meticulous understanding of a pathogen's infection mechanisms is the best way to achieve successful management of a disease. This study was carried out to evaluate the pathogenicity of C. truncatum on selected crop plants and weed species and to detect the possibility of non-host species to facilitate survival of the pathogen. Inoculation of an isolate of C. truncatum to four crops: curry chilli -Capsicum annuum (var. CA8), eggplant -Solanum melongena (var. Lena Iri), tomato -Solanum lycopersicum (var. Thilina) and green chilli -C. annuum (var. KA2) and three weed species: little ironweed (Vernonia cinerea), billygoat-weed (Ageratum conyzoides) and Bengal dayflower (Commelina benghalensis) resulted in approximately 3.5 disease severity (DS) (100% disease incidence-DI) on S. lycopersicum and C. annuum (var. KA2), followed by 2.8 and 1.8 DS (100%, 75% DI) on C. annuum (var. CA8) and S. melongena (var. Lena Iri), respectively. The three weed species were completely symptomless up to 8 weeks after the inoculation (WAI). However, microscopic studies and serial culturing of the inoculated tissues revealed the presence of the fungus in all the tested plants. Appressoria were present in all treated leaves and eventually broke their dormancy upon leaf senescence nearly 6 WAI. This study reveals the potential of C. truncatum infecting all tested crops and the capability of the three weed species in harboring the pathogen asymptomatically for several weeks. Thus, early management of inoculum in the field is suggested for C. truncatum diseases.

Genome sequencing and comparative genomics reveal a repertoire of putative pathogenicity genes in chilli anthracnose fungus Colletotrichum truncatum

“…The expression of these CAZymes after host invasion may be responsible for the stealth strategy employed by C . truncatum during endophytic or quiescent phase of infection that has been observed even in a susceptible host like chilli [ 16 , 103 ].…”

“…Recent studies suggest that C . truncatum colonises chilli through subcuticular intramural necrotrophy with a brief asymptomatic, endophytic phase after initial infection and prior to necrotrophic development [ 15 , 16 ]. Still, it contrasts with the hemibiotrophic lifestyle that is followed by most of the Colletotrichum species.…”

The Landscape of Repetitive Elements in the Refined Genome of Chilli Anthracnose Fungus Colletotrichum truncatum

“…The Colletotrichum species usually exhibit hemibiotrophic lifestyle to infect the host plants, whereas C. truncatum adopts subcuticular intramural necrotrophic lifestyle during interaction with chilli (with short endophytic phase) and other hosts like cotton, cowpea etc. ( Perfect et al, 1999 ; Ranathunge et al, 2016 ). A pathogen with such a broad host range and varied lifestyle might have evolved constantly and adapted to different niches over the time in a continuous armed race with different hosts.…”

Türkiye'de Sera Domatesinde Colletotrichum truncatum’un Karakterizasyonu ve Haplotip Analizi

“…These fungi, which can be found endophytically in the plant, can be used as a biological control agent in the control of insects (Marcelino et al, 2009). It has been reported that the C. truncatum is found endophytically in the plant (Ranathunge and Sandani, 2016). There is no literature on the presence of entomopathogenic biovars in the species.…”