Colletotrichum species associated with durian (Durio zibethinus Murray) in Hainan, China

Durian (Durio zibethinus Murray), the king of fruits, is an edible and economically important tropical fruit endemic to Southeast Asia. Durian is affected by Colletotrichum, which is one of the most important genera of plant pathogenic fungi, especially on tropical and subtropical crops. In this study, Colletotrichum species associated with durian in Hainan (China) which was a new region for durian cultivation were studied using phylogenetic and morphological analyses. The results of molecular identification based on internal transcribed spacer (ITS), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), β-tubulin (TUB2) and the mating type locus MAT1-2 (ApMat) along with microscopic identification indicated that seven species from three species complexes were identified, including C. fructicola, C. siamense, C. queenslandicum and C. endophyticum from the gloeosporioides species complex; C.plurivorum and C. musicola from the orchidearum species complex, and C. gigasporum from the gigasporum species complex. Colletotrichum fructicola and C. siamense were the main Colletotrichum species associated with durian in Hainan. Pathogenicity tests showed that all seven species could infect durian leaves using a wound inoculation method but only C. fructicola, C. queenslandicum and C. endophyticum could infect using a non-wound inoculation method. The findings from this study enhance the knowledge of durian diseases and lay an essential foundation for devising effective disease management approaches. Further large-scale surveys are necessary, including sampling different sites and plant tissues, pathogenicity testing on a wider range of host genotypes and fungicide-sensitivity evaluation among and within the different Colletotrichum species collected.