Abstract:
Objective Pathogen causing anthracnose on Passiflora edulis in Guangxi was identified and its biological characteristics determined.
Method Tissue isolation method was employed to isolate as well as to examine the pathogenicity and colony characteristics on petri dishes of potential pathogens. Analysis on sequences of ITS, CAL, and ApMat was applied to confirm the pathogen identification.
Result From the tissues of passion fruits showing typical anthracnose lesions, tg3b1 was isolated, purified, and identified to be Colletotrichum theobromicola. Statistically significant at P<0.05, the largest diameter mycelial colonies and most spores of the isolate were cultured at 25-28°C and pH 6.0; the mycelial growth was not sensitive to light conditions, but the spore production encouraged by alternated light and darkness; the colonies grew to larger diameter on a PSA medium than on 8 other media, while the spores more numerous on OA and PDA; the media using glucose for carbon produced colonies with bigger diameters and denser mycelia, as D-fructose and glucose boosted the spore production (but not so with lactose); the use of yeast powder for nitrogen rendered larger colonies, whereas the media formulated with glycine and L-arginine generated more spores; and the mycelium mortality could be induced in 10 min at 51°C.
Conclusion C. theobromicola was identified as the pathogen that caused anthracnose on passion fruits in Guangxi. In culture, it grew optimally at 25-28°C and pH 6.0 with no specific requirement for light on a PSA medium containing glucose and yeast powder. Maximal spore count was observed on a PSA medium consisting of D-fructose, glucose, glycine, and L-arginine at 25-28°C and pH 6.0 under alternated light and darkness. An exposure to 51°C for 10 min was lethal to the pathogen.