Role of PGPR in suppressing the growth of Macrophomina phaseolina by regulating antioxidant enzymes and secondary metabolites in Vigna radiata (L.) R. Wilczek
Amjid Khan, Asghari Bano, Rashid Abbas Khan, Naeem Khan
Abstract
This study was conducted to evaluate the effect of PGPR on Vigna radiata L. resistance against Macrophomina phaseolina-associated charcoal rot. The seeds of Vigna radiata L. (cv. NM-11 and cv. Chakwal) were inoculated with two bacterial strains i.e., Pseudomonas stutzeri (KX574858) and Pseudomonas putida (KX574857). Under unstressed conditions, both PGPR were effective enough to exhibit that their inoculation imparts tolerance to plants against the infection in a much better way than untreated plants acting as a control. The Vigna radiata cv. Chakwal (V2) showed more positive response to the PGPR treatment by enhancing the contents of chlorophyll a (1.52-fold), carotenoids (95%), and sugars (2.16-fold. Although PGPR inoculation significantly enhanced the accumulation of phenolics, flavonoids, and proline by 22%, 47%, and 69% respectively. The plant growth, yield, and defense-related enzymatic activities were remarkably improved in P. putida treated plants under infected conditions. This leads to a notable amelioration in phenylalanine ammonia-lyase, polyphenol oxidase, superoxide dismutase, and peroxidase by 100%, 70%, 110%, and 21% sequentially. Pseudomonas putida conciliated inhibition in the growth of M. phaseolina and the results of the study demonstrates that P. putida is a more effective bio-fungicide than P. stutzeri. It is concluded that the biocontrol potential of P. putida is greater than that of P. stutzeri whereas the P. stutzeri exhibited greater plant growth promoting activities.