Identification and characterization of Colletotrichum species associated with ornamental plants in Southern China

Abstract

Colletotrichum is an important plant pathogenic genus with a wide range of hosts. Colletotrichum species can infect various plants and cause diseases, leading to serious economic losses. Ornamental plants are an important commercial crop with high aesthetic value and emerging diseases have become a serious problem threatening the ornamental plant industry. However, little is known about the fungi and fungal species associated with ornamental plants in China especially latent pathogens such as Colletotrichum spp. In the present study, 45 Colletotrichum isolates were obtained from 17 ornamental plants with typical symptoms including leaf spot and stem blight. These isolates were further identified based on morphological analysis, multigene molecular phylogenetic analysis of the internal transcribed spacer regions (ITS), actin (act), partial sequences of the chitin synthase 1 (chs-1), glyceraldehyde 3-phosphate dehydrogenase (gapdh), and β-tubulin 2 (tub2) genes, and pairwise homoplasy index (PHI) analysis. Based on multigene phylogenetic analysis and morphology 11 species of Colletotrichum were identified belonging to five species complexes: C. acutatum, C. boninense, C. gloeosporioides, C. orchidearum and C. truncatum. Among these complexes, one species was described as new species namely, C. chrysalidocarpi. In addition, C. dimorphum, and C. nanhuaense are reduced as synonyms of C. gloeosporioides and C. orientale and C. radermacherae are reduced as synonyms of C. fioriniae. Furthermore, 18 new host records were identified and described. This is the first comprehensive study on Colletotrichum species associated with ornamental plants in South China. Our results suggested a high Colletotrichum species diversity on ornamental plants. These findings enhance the current knowledge of Colletotrichum, and its diversity and expand the host range. In addition, these results will help to early diagnose, and control diseases caused by Colletotrichum species.