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Accueil du site → Doctorat → Inde → 2018 → A Study on the Beneficial Effects of Rhizobacteria on Physiological Status Proline Metabolism and Endogenous one Accumulation in Arabidopsis thaliana Under Water stress

Birla Institute of Technology and Science (2018)

A Study on the Beneficial Effects of Rhizobacteria on Physiological Status Proline Metabolism and Endogenous one Accumulation in Arabidopsis thaliana Under Water stress

GHOSH DAIPAYAN

Titre : A Study on the Beneficial Effects of Rhizobacteria on Physiological Status Proline Metabolism and Endogenous one Accumulation in Arabidopsis thaliana Under Water stress

Auteur : GHOSH DAIPAYAN

Université de soutenance : Birla Institute of Technology and Science

Grade : Doctor of Philosophy (PhD) 2018

Résumé
Although the physiological benefits of plant growth promoting rhizobacteria (PGPR) to plants are well reported, the precise mechanisms that make these PGPR such wonderful friends of plants under adverse environmental conditions are still under investigation. We have investigated the role of a drought tolerant PGPR strain, Pseudomonas putida GAP-P45 in ameliorating the negative impacts of water-stress in Arabidopsis thaliana and have studied some aspects of the underlying mechanisms of such beneficial plant-PGPR interaction. We have studied the effects of P. putida GAP-P45 on (a) morpho-physiological characteristics (b) proline metabolism and (c) phytohormone accumulation in A. thaliana under water-stress. Plants inoculated with P. putida GAP-P45 exhibited characteristics of water-stress mitigation by improvement of morpho-physiological parameters such as better growth, increased fresh weight, enhanced plant water content, reduction in primary root length, enhanced chlorophyll content in leaves and increased accumulation of endogenous proline content, when compared to non-inoculated water-stressed plants. We observed that P. putida GAP-P45 alleviated the effects of water-stress in A. thaliana by causing drastic changes in proline metabolic gene expression at different time points post stress induction. Quantitative real-time analysis of proline metabolic gene expression in inoculated plants under water-stress showed a delayed but prolonged upregulation of genes involved in proline biosynthesis, i.e., ornithine-and#916 ;-aminotransferase (OAT), and#916 ;1- pyrroline-5-carboxylate synthetase1 (P5CS1), and#916 ;1-pyrroline- 5-carboxylate reductase (P5CR), as well as proline catabolism, i.e., proline dehydrogenase1 (PDH1) and and#916 ;1-pyrroline- 5-carboxylate dehydrogenase (P5CDH). We also analyzed the impact of this PGPR strain on the activity of proline metabolic enzymes encoded by the aforementioned genes and observed that inoculation of A. thaliana with P. putida GAP-P45 under water-stress modulated the proline metabolic enzyme

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