Systemic resistance induced by plant growth-promoting rhizobacteria in Bhut Jolokia (Capsicum chinense Jacq.) suppressed the collar rot disease
Priyanka Gogoi, Tridip Phukan, Ratul Saikia
Abstract
Collar rot disease caused by Rhizoctonia solani is a major constraint to the commercial cultivation of Bhut Jolokia ( Capsicum chinense Jacq.) in North-East India. However, the management of the disease is not addressed comprehensively in this plant. Some plant growth-promoting rhizobacteria (PGPR) could control plant diseases by triggering induction of resistance systemically, and emerge as a highly promising approach to reduce the use of chemical fungicides. Therefore, five selected PGPRs were tested for plant growth promotion and induced systemic resistance (ISR) for controlling the disease. Induced systemic resistance was determined in vivo condition. Confocal laser scanning microscopic observation was done to see any harmful effects on cells in the induced plant. The PGPRs could significantly improve plant growth as well as suppress the disease and boost defense-related enzymes activity in the induced plants. Bacillus megaterium JPR68 triggered the maximum ISR in the plant. Expression of the defense-related genes was analyzed which were highly expressed in ISR plants. Microscopic observation revealed that no internal changes occurred in PGPR treated plant cells similar to the untreated plant, and indicated no harmful effect of the bacteria in the host cell. The study demonstrates the possible application of B. megaterium JPR68 as a biocontrol agent for sustainable management of the disease. To our knowledge, this is the first report of ISR against any fungal disease in Bhut Jolokia.