Potential of Cross-infection of Colletotrichum Species Causing Anthracnose in Persimmon and Pepper

Abstract

Ninety isolates of Colletotrichum species from new persimmon tree twigs and 50 isolates from pepper plant fruits were isolated via single-spore isolation. Of the 140 isolates, 26 were examined for mycelial growth, carbendazim sensitivity, and ITS sequence. Four of the isolates from the persimmon trees, which were cultivated exclusively in an orchard, showed fast mycelial growth and sensitivity to carbendazim, while five of the pepper isolates showed slower mycelial growth and were resistant to the fungicide. However, 17 isolates from persimmon trees cultivated with pepper plants in the same orchard showed slow mycelial growth like the pepper isolates and they were sensitive to carbendazim like the persimmon isolates. ITS sequence analysis of these 27 isolates led to the identification of the 22 persimmon isolates as C. gloeosporioides and the five pepper isolates as C. acutatum. PCR with species-specific primers confirmed that the 90 isolates from persimmon were C. gloeosporioides whereas the 50 isolates from pepper were C. acutatum. The 90 persimmon isolates of C. gloeosporioides and 50 pepper isolates of C. acutatum were compared by a wound inoculation test to determine their capacity for host cross-infection. All of the C. acutatum isolates from pepper caused typical symptoms of anthracnose on the fruits of pepper plants and twigs of persimmon; they differed from the C. gloeosporioides isolates from persimmon, more than 90% of which were able to infect only persimmon. Amplified fragment length polymorphism analysis revealed the existence of two groups (C. gloeosporioides and C. acutatum isolates group). At 80% genetic similarity, the C. gloeosporioides group was defined within four clusters, while the C. acutatum group was within three clusters. However, these clusterings were unrelated with the virulence of Colletotrichum species against pepper fruits.