Impact of endophytic bacteria against yellow rust (Puccinia striiformis f. sp. tritici) of wheat

Wheat is a dominant cereal crop worldwide and very important as a staple food resource. A number of pathogens cause damage to wheat crop, of which yellow rust caused by Puccinia striiformis f. sp. tritici is one of the major threats to wheat production in India. Chemical control leads to resistance development against the pathogen. Biological control, the use of natural antagonists to combat plant diseases has emerged as a promising alternative to chemical pesticides. Keeping in view the importance of the disease the present investigation was undertaken with the aim to observe the impact of endophytic bacteria Pseudomonas fluorescens and Bacillus amyloliquefaciens as biocontrol agents against yellow rust of wheat. Talc based bioformulations of two bacterial biocontrol agents, viz. Pseudomonas fluorescens and Bacillus amyloliquefaciens were used at different concentrations to observe their effectiveness against yellow rust. In addition to this, the activity of various defense related enzymes Peroxidase (PO), Polyphenol oxidase (PPO), Phenylalanine Ammonia Lyase (PAL) along with Phenols and Proteins was also observed. Our findings indicated that the yellow rust severity in P. fluorescens (T14) fermented liquid (FL) (PF) @15 g/l of water as foiler spray exhibited 43.71 per cent and it gave 50.07 per cent disease control in rabi 2015. Whereas B. amyloliquefaciens (T3) fermented liquid bacterial cell (FLBC) (FDK21) @15 g/kg of seed showed 53.25% disease severity along with 39.20% disease control in rabi 2015 and enhanced the grain yield. Both the treatments were significantly better than the untreated control. But they were less superior than the chemical control. Similar trend has been observed in rabi 2016 season. The activity of the defense related enzymes that is PO, PPO and PAL as well as phenol and protein content was observed to be elevated in P. fluorescens T4(54.35 Units min-1 g-1 F W), T10( 24.39 Units min-1 g-1 F W), T14(103.36 μg t-cinnamic acid formed hr-1 g-1), T10 (6.89 mg/g F W) and T14(111.56 mg/g F W) and B. amyloliquefaciens T3(29.01 Units min-1 g-1 F W), T3(19.54 Units min-1 g-1 F W), T3(97.98 μg t-cinnamic acid formed hr-1 g-1), T3(46.89 mg/g F W), T3 (98.08 Units min-1 g-1 F W)) treated wheat plants as compared to chemically treated (T2 19.77 Units min-1 g-1 F W, 7.41 Units min-1 g-1 F W, 97.94 μg t-cinnamic acid formed hr-1 g-1, 2.93 mg/g F W, 72.40 mg/g F W) and untreated control plants ( T1 13.61 Units min-1 g-1 F W, 1.90 Units min-1 g-1 F W, 88.73 μg t-cinnamic acid formed hr-1 g-1 , 2.74 mg/g F W, 44.90 mg/g F W). Since several strains of Pseudomonas and Bacillus can act as BCA through an induced systemic resistance response in the plant against pathogens. So these biocontrol agents played major role through an induced systemic resistance response in the plant against pathogens and also help the plant in accelerating their defense response against the pathogens. Therefore it is suggested that the novel use of biocontrol agents Pseudomonas fluorescens and Bacillus amyloliquefaciens.