Implications of plant growth promoting rhizobacteria and their consortia for biofortification of Fe and Zn content in wheat under saline and non saline soils
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Date
2019-06
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
Present study was an attempt to characterize plant growth promoting halotolerant rhizobacteria isolated from paddy rhizosphere of different region’s saline soils bearing massive competence for zinc solubilization and siderophore production. Furthermore, explorations were led to determine in situ effect of potential isolates and their consortia on growth and biofortification benefits through enhanced zinc and iron assimilation in wheat under saline and non saline soils. Total 146 bacteria were isolated from rice rhizosphere of both saline and non saline soils habitats and among these, 44 bacterial isolates were screened on the basis of zinc solubilizing potential, siderophore production and higher tolerance ability under NaCl and PEG stress. Finally, 4 bacterial isolates bearing multiple plant growth promoting potential were selected and characterized on the basis of morphological and biochemical tests. On the basis of bio compatibility, two bacterial consortia (C1 and C2) were developed from potential 4 isolates having zinc solubilizing and siderophore production ability under high NaCl concentration and used for the further study with selected four isolates. Selected bacterial isolates were characterized on the basis of 16S rDNA found to be phylogenetically related to four genera, namely Providencia vermicola, Pseudomonas protegens, Klebsiella pneumoniae and Pseudomonas sp. and were also found to have stress responsive acdS gene. UPLC-MS analysis of cell free supernatant obtained from zinc amended mineral medium revealed major organic acids (salicylic acid, carboxylic acid, acetic acid, succinic acid and lactic acids) produced by four bacteria depicts a key mechanism of zinc soubilization. All four isolates and two consortia were evaluated for their effect on seedling germination efficiency under different NaCl concentration, and among them consortium C2 showed prominent influence on germination efficiency over other treatments. Afterwards, isolates and consortia also showed positive and significant influence on agronomical as well as physiological and growth parameters through in situ green house pot experiment in Triticum aestivum var. PBW373 under both saline and non-saline soil systems. Moreover, the soil enzymatic activities were found at utmost level in soils (saline and non saline) of both consortium (C1 and C2). After harvesting, soil and plant samples were analyzed for zinc and iron assimilation through Atomic Absorption Spectroscopy (AAS). Both consortia and isolates (CP20 and CP17) assimilated enhanced level of Zn and Fe in wheat significantly over negative control. Proteomic studies revealed 33 differentially expressed proteins (23 up-regulated and 10 down-regulated) in 25th days seedling inoculated with C2 were related to stress tolerance, transporter and nutrient reservoir proteins. Present study provide an overview of employing microorganisms and their consortia as effective bioinoculants to drive biofortification of food crops in more eco-friendly environment to improve sustainable agriculture even in salinity stress.
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