Bacillus amyloliquefaciens Modulate Carbohydrate Metabolism in Rice-PGPR Cross-Talk Under Abiotic Stress and Phytohormone Treatments

Rice is one of the world’s most important food crop that is severely affected by abiotic stresses. In our earlier study, inoculation with Bacillus amyloliquefaciens SN13 (SN13) improved the growth of rice seedlings under salt and drought stress as compared to other abiotic stresses was demonstrated. Therefore, the present study was carried out to understand the possible mechanism induced by B. amyloliquefaciens for salt and drought tolerance. Further, the role of SN13 in phytohormone-induced stress tolerance by exogenous application of abscisic acid and ethylene was investigated. The SN13 inoculated rice seedlings showed significantly better performance as demonstrated by physio-biochemical, antioxidant enzyme activities, and nutrient analysis. The expression of positively regulated stress-responsive genes was found under abiotic stresses and phytohormone treatments in inoculated seedlings indicating its multifaceted role in abiotic stresses and phytohormone cross-talk in response to PGPR. Inoculated seedlings also showed altered metabolites primarily related to carbohydrates (glucose, galactose, fructose, ribose, trehalose, turanose, hexapyranose, and xylose) and fatty acid (dodecanoic acid, eicosenoic acid, hexadecanoic acid, linolenic acid, and octadecadienoic acid) metabolism. These findings affirm that B. amyloliquefaciens SN13 positively modulates plant nutrient status, stress-responsive genes, and metabolic pathways related to carbohydrate and fatty acid metabolism supporting its involvement in cross-talk between imposed stresses and phytohormones.