Characteristics and distribution of Colletotrichum species in coffee plantations in Hainan, China

Abstract

Anthracnose caused by Colletotrichum species is a serious disease on a range of economically important hosts. To determine the Colletotrichum species in coffee plantations in Hainan, China, 55 isolates were obtained from Coffea arabica (arabica) and C. canephora var. robusta (robusta) in five counties. Initially, partial sequences of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) were used to measure fungal genetic diversity. Then a subset of 23 isolates was selected to represent the range of genetic diversity, varieties and geographic origin for further multilocus phylogenetic analyses. These isolates belong to eight known Colletotrichum species from three Colletotrichum species complexes, including gloeosporioides (C. endophytica, C. fructicola, C. ledongense, C. siamense and C. tropicale), boninense (C. karstii), gigasporum (C. gigasporum), and one singleton species (C. brevisporum). Of these, C. siamense was isolated in all sampled counties and C. fructicola was identified in three counties. The other six species were isolated only in one or two counties. Only C. siamense and C. fructicola were isolated from arabica, whereas all eight species were isolated from robusta. Occurrence of C. brevisporum, C. endophytica, C. ledongense and C. tropicale in coffee has not been reported previously. Pathogenicity tests showed that all eight species were pathogenic to coffee leaves and fruit. In vitro tests showed that Colletotrichum isolates from coffee in Hainan were most sensitive to prochloraz, less sensitive to carbendazim, propiconazole and difenoconazole, and least sensitive to myclobutanil.

Population structure, pathogenicity, and fungicide sensitivity of Colletotrichum siamense from different hosts in Hainan, China

“…The C . siamense isolates were tested for their fungicide sensitivity in fungicide‐amended agar as described previously (Cao et al, 2019b). Carbendazim, an MBC fungicide, and three DMI fungicides (prochloraz belonging to the imidazoles, propiconazole and difenoconazole belonging to the triazoles) were used for fungicide sensitivity assessment.…”

“…), supplied by Hainan Zhengye Plates were incubated at 25 °C for 5 days in the dark and mean colony diameter (minus the diameter of the initial inoculation plug) was determined and expressed as percentage growth inhibition. The average 50% effective dose (EC 50 ) value was estimated for each isolate and fungicide combination in linear regression analysis, where the percentage of mycelial growth inhibition was regressed against the log 10 of fungicide concentrations (Cao et al, 2019b). There were three replicate plates for each combination of isolate and fungicide concentration.…”

“…Plant‐pathogenic Colletotrichum species are often described as causing typical symptoms of anthracnose disease, including spots and sunken necrotic lesions on leaves, stems, flowers, and fruits, but they can cause other symptoms such as red rot on sugar cane, crown rot on strawberry and banana, and brown blotch on cowpea (Cannon et al, 2012). Anthracnose is an important disease of rubber tree, coffee, and areca palm in Hainan, resulting in significant yield losses (Cao et al, 2019a, 2019b, 2020).…”

“…It has been confirmed that C . siamense is the dominant species that causes anthracnose on these three crops in Hainan (Cao et al, 2019a, 2019b, 2020).…”

“…Anthracnose is an important disease of rubber tree, coffee, and areca palm in Hainan, resulting in significant yield losses (Cao et al, 2019a(Cao et al, , 2019b(Cao et al, , 2020.…”