Functional and molecular characterization of rhizobacterial antagonists against foliar blight pathogens of wheat, Bipolaris sorokiniana and Alternaria triticina
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Date
2021-02
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
Foliar blight pathogens affect the wheat production and growth worldwide. The application of chemical fertilizers to control the disease has harmful effects to human health and environment. Fortunately, rhizobacteria can be used as an alternative strategy for the sustainable disease management. In present study, a total of forty five rhizobacteria isolated from rhizosphere soil of wheat cultivated in five agroclimatic regions across four India states were tested for in vitro antagonistic activity against two foliar blight pathogens; Bipolaris sorokiniana and Alternaria triticina causing wheat spot blotch and leaf blight respectively. In addition, all 45 rhizobacteria were tested for production of hydrolytic enzymes (chitinase, protease, cellulase, amylase, and lipase) and PGP traits (solubilization of phosphate & zinc, production of ammonia and siderophore). Six isolates scoring (Ʃ=>12) on bonitur scale were selected for further studies. The isolates P10, UP11, MH13, MP17, MH12, and MP14 were subsequently identified as Bacillus methylotrophicus (MN099430.1), Bacillus subtilis (MN099431.1), Bacillus sp. (MN099432.1), Streptomyces sp. (MN099435.1), Lysinibacillus sp. (MN099433.1), and Staphylococcus epidermidis (MN099434.1) respectively. In vivo pot trial revealed that seed bacterization plus booster dose of bacterial treatments resulted in lowest disease incidence (DI %) than foliar spray 24 hrs after pathogen infection against both the foliar blight pathogens. Reduction in spot blotch incidence in wheat plants treated with the isolates P10 (T2) UP11 (T3) was significant with48.66% and 50.33 % DI respectively. Likewise, percrent reduction in the incidence of leaf blight by P10 and UP11 was 49.26% and 50.33% respectively. The pot experiments also revealed that P10 and UP11 considerably increased plant biometric parameters. Therefore, B. methylotrophicus strain P10 and B. subtilis strain UP11 were equally effective to control both the foliar blight pathogens individually as well as in a complex. Antifungal metabolites produced by P10 and UP11 were analyzed in ethyl acetate extract by GC-MS and 29 and 30 compounds were identified respectively. A compound, isobutylhexahydropyrrolo [1, 2-a] pyrazine-1, 4-dione was dominant and abundant in both the strains. In silico studies revealed a strong interaction (ΔG-6.76) between the dominant compound and, ceratoplatinin, a phytotoxic protein of fungus B. sorokiniana. Hence, we suggest that strain P10 and UP11 has the potential to be used in sustainable agriculture.