The variations of five Colletotrichum strains from strawberry in mycelial growth and pathogenicity below 26℃

Abstract

Abstract Anthracnose caused by Colletotrichum spp. is a serious threat to many crops. C. siamense has been increasingly prevalent recently. However, the biology and pathogenicity of these fungi was largely elusive, especially below 26°C. Currently, the mycelial growth of five representative Colletotrichum strains including three C. siamense, one C. fructicola and one C. gloeosporioides s.s. strain from diseased strawberry was characterized at 10, 14, 18, 22 and 26℃. Their pathogenicity to two hosts under 14℃ and 22℃ was investigated. These strains did not differ much in mycelium growth between 10–26℃, although all C. siamense and C. gloeosporioides s.s. strains showed some superiority than C. fructicola. However, great variations were observed in their pathogenicity to Fragaria vesca and F. × ananassa cv. ‘Benihoppe’. The strain Cs:GQHZJ19 with fastest mycelial growth at 22℃ was also the most virulent to both hosts under 14 / 22℃. But the mycelial growth rate was only positively correlated with C. siamense pathogenicity to the susceptible cv. ‘Benihoppe’ at 3 dpi under 22℃. Based on the pathogenicity analysis for five Colletotrichum strains on hosts with varying susceptibility under distinct temperatures, this work suggested that host genotype might play a decisive role in disease severity from the beginning of infection, while temperature could shape host-Colletotrichum spp. interaction at a later infection stage. Future studies with more fungal samples are required to determine the biology and virulence of Colletotrichum strains (especially C. siamense) in a wider temperature range, which will eventually facilitate an effective management of crop anthracnose.