Endophytic Bacillus spp. from native chilli cultivars and their effect against fruit rot pathogen of Bhut Jolokia (Capsicum chinense Jacq.)

Abstract

Abstract Background Fruit rot disease is one of the most important factors limiting the production potential of Bhut Jolokia (Capsicum chinense Jacq.), which is known as one of the hottest chillies in the world. The management strategies are highly dependent on synthetic chemicals which are causing a detrimental impact on the environment. Considering the factors, this study focuses on exploring potential endophytic microflora from native chilli cultivars which can suppress the fruit rot pathogen. Results Endophytic microflora occurs ubiquitously in plants that possess various plant-benefiting abilities. A total of 34 endophytic isolates were obtained from different chilli cultivars. These endophytic isolates were subjected to screening in vitro for their potential to suppress the incitant pathogen Colletotrichumgloeosporioides (the causal agent of chilli fruit rot), which was confirmed based on cultural, morphological, pathogenicity and molecular studies. The preliminary screening yielded four bacterial endophytic isolates capable of suppressing the pathogen which was found non-pathogenic to Bhut Jolokia plant. On the basis of morphological, biochemical and molecular identification, the four most promising isolates were identified as Bacillus velezensis, B. mycoides, B. altitudinis and B. cereus, respectively, and used for further in vitro tests. B. velezensis showed the highest inhibition (68.67%) on mycelial growth of C. gloeosporioides, followed by B. mycoides (65.33%), B. altitudinis (52.89%) and B. cereus (45.33%). Among the compatible combination, the highest efficacy (56.00%) was found in the combination of B. velezensis and B. altitudinis. Conclusion From the present study, it can be concluded that B. velezensis and B. mycoides alone and in combination can be used as potential biocontrol agent in managing the fruit rot of Bhut Jolokia considering their performance in field conditions.