Identification and biological characteristics of the anthracnose pathogen of postharvest banana fruit

Four isolates of the anthracnose pathogen were isolated from postharvest banana fruits displaying anthracnose symptoms by using tissue isolation technique.The differences in mycelial growth rate,conidial germination,appressorium formation and pathogenicity of the four isolates were compared under the same conditions.The results showed that there was no significant difference in the mycelial growth rate,but the percentages of conidial germination and appressorium formation,and the pathogenicity of isolate X4 were significantly higher than those of the other 3 isolates.The isolate X4 was identified as Colletotrichum musae based on the classical morphological taxonomy combined with the technique of ITS sequence analysis.Meanwhile,the effects of temperature,illumination and pH value on the mycelial growth,conidial germination and appressorium formation of isolate X4 were investigated.The results indicated that the temperatures for the mycelial growth were ranged from 10-35 ℃,with an optimum of 28 ℃ and the suitable temperatures for conidial germination and appressorium formation were from 25-30 ℃,with an optimum of 28 ℃.Illumination had no significant effect on the linear growth of mycelium,conidial germination and appressorium formation.The pH values for the mycelial growth and conidial germination were 5.0-8.0,with an optimum of pH 6.0.The lethal temperature of conidia and mycelia explored further were 50 ℃/10 min.