Molecular Analysis of Rhizobacteria Inoculated Peanut and Tomato for Induced Systemic Tolerance

Abstract

Rhizobacteria are of great economic importance in agriculture for growth newlinepromotion and stress alleviation in plants. Among 480 rhizobacteria screened in vitro newlinefor water stress tolerance, 62 were tolerant in medium with 30 per cent polyethylene newlineglycol. Twenty seven isolates with IAA production activity screened in green house newlineunder water deficit stress conditions, actinobacteria performed better. newlineThe inoculation of actinobacteria increased root length, shoot length, root dry newlineweight and shoot dry weight of peanut and tomato plants. Out of 13 isolates, three newlineactinobacteria AUUB290, AUDT545 and AUDT559 were significantly efficient in newlineameliorating water stress under greenhouse conditions. Streptomyces luteogriseus newline(AUDT545) was most promising at imparting water stress tolerance. AUDT545 newlineincreased leaf relative water content (78%) and survival rate (89%) of peanut plants newlineunder water stress. Tomato plants inoculated with AUDT545 performed better with newlineincreased relative water content (83.6%) and survival percent (94%) of plants under newlinewater deficit stress. Biochemical assays of actinobacteria inoculated peanut and tomato newlineplants showed increased chlorophyll content and reduced proline, total soluble sugar, newlineand catalase, peroxidase and glutathione reductase activity. newlineThe differentially expressed genes in AUDT545 inoculated peanut and tomato newlineleaf transcriptomes during induced systemic tolerance (IST) were studied through RNA newlinesequencing. A total of 1170 genes in peanut and 241 genes in tomato were differentially newlineexpressed. The upregulated genes were mainly involved in hormone signaling newlinepathways, photosynthesis, aquaporins, carbohydrate metabolism, fatty acid metabolism, newlinemembrane trafficking, signaling and cell wall related. Genes related to cutin, suberin newlineand wax biosynthesis were upregulated. The downregulated genes were mainly newlinetranscription factors like ethylene-responsive transcription factor ABR1-like, mitogenactivated newlineprotein kinase, ethylene-responsive transcription factor and newlineaminocyclopropane carboxylate oxidase. Thes