Comparative evaluation of different bioformulations of PGPR cells on the enhancement of induced systemic resistance (ISR) in Rice P. oryzae pathosystem under upland condition

摘要

The comparative evaluation of different bioformulations, viz.,vegetative cell application, co-inoculation and co-aggregates application of efficient PGPR cells viz., Pseudomonas fluorescens (PF-3) and Paenibacillus polymyxa (B-19), together with challenge inoculation of Pyricularia oryzae on the enhancement of induced systemic resistance (ISR) in Rice-Pyricularia oryzae pathosystem was studied under pot culture condition with rice cv.ASD-19. It was observed that the application of Pseudomonas fluorescens and Paenibacillus polymyxa, as co-aggregates, altered the biochemical and physiological parameters viz., reducing and non-reducing sugars, total phenol content and defense enzymes activities such as peroxidase (PO), polyphenol oxidase (PPO), of rice plant to a significant level followed by co-inoculation and vegetative cell application of PGPR ?? cells. The application of PGPR cells, as co-aggregates, was found to augment the total phenol content and defense enzyme activities such as PO and PPO content of rice plant to a higher level whereas a reduction in reducing and non-reducing sugar level was recorded, which ultimately lead to a reduction of Pyricularia oryzae incidence in upland rice. It has been postulated that the EPS biosynthesis of PGPR cells during co-aggregation processes might act as elicitor for the enhancement of ISR in Rice-Pyricularia oryzae pathosystem whereas the vegetative cells and co-inoculation processes, without any involvement of EPS, responded poorly for the enhancement of ISR in the same pathosystem. This is the first comprehensive report on the role of bacterial EPS, as a determinant of ISR, in Rice - Pyricularia oryzae pathosytem and it needs further elaborate research on the topic.