Exploration of Endophytes from Tropical Tuber Crops against Colletotrichum gloeosporioides Causing Anthracnose in Greater Yam (Dioscorea alata L.) In Vitro

Abstract

The study was aimed to identify and characterize the endophytes from tropical tuber crops against Colletotrichum gloeosporioides causing anthracnose in greater yam. The pathogen was isolated from anthracnose infected greater yam leaves and its virulence and identity were confirmed. The fungal and bacterial endophytes were isolated from greater yam (vars. Sree Keerthi, Sree Karthika and acc. nos., Da 251 and Da 262), taro (Muktakeshi), Chinese potato var. and arrow root var. Endophytes were screened against the pathogen by dual culture method. Among 139 endophytes isolated, morphologically distinct 37 bacterial and 37 fungal endophytes were selected for in vitro screening. Three bacterial endophytes with antifungal index of 88.6, 85.7 and 84.6% and four fungal endophytes with antifungal index of 67.1, 55.7, 49.3 and 45.3% were obtained. Potential bacterial and fungal endophytes were identified using 16S rRNA and ITS1 - ITS4 primers, respectively. Using molecular techniques, the potential endophytes were identified. Among the three bacterial endophytes, one was Bacillus cereus and two were Bacillus subtilis. The fungal endophytes were identified as Penicillium citrinum, Phanerochaete australis, Curvularia pseudobrachyspora and Diaporthe batatas. There is great potential in utilizing the endophytes such as Bacillus cereus and Bacillus subtilis for managing the disease. This could be a novel, ecofriendly and effective biocontrol strategy for managing anthracnose disease in greater yam.