Inoculation of Klebsiella variicola Alleviated Salt Stress and Improved Growth and Nutrients in Wheat and Maize

Abstract

Although wheat and maize are the major economically important cereal crops and staple food sources in the world, their productivity is highly affected by excess salts in soil (salinity). Applications of multifarious halophilic plant growth-promoting rhizobacteria (PGPR) in saline soil protect the plants from osmotic damages and promote plant growth through the secretion of plant growth promoting (PGP) and osmolytes. In this study, Klebsiella variicola SURYA6—a PGPR—was evaluated for plant-growth-promotion and salinity amelioration in wheat and maize, and enrichment of soil nutrients. The results of the present study revealed that K. variicola SURYA6 grows luxuriously under high salinity stress conditions and produces copious amounts of three principal salinity ameliorating traits, such as 1 aminocyclopropane-1-carboxylate deaminase (ACCD), indole-3-acetic acid (IAA), exopolysaccharides (EPS), and osmolytes—such as proline, sugars, proteins, and amino acids. The isolate also exhibited sensitivity to a wide range of antibiotics, lack of hemolytic ability, and absence of catalase and oxidase activities confirming its nonpathogenic nature. Inoculation of wheat and maize seeds with this multifarious strain, improved the physicochemical properties of soil, improved seed germination by 33.9% and 36.0%, root length by 111.0%, 35.1%, shoot height by 64.8% and 78.9%, and chlorophyll content by 68.4% and 66.7% in wheat and maize seedlings, respectively, at 45 days after sowing (DAS) under salinity stress. The improvement in plant growth can be correlated with the secretion of PGP traits and improved, uptake of minerals such as nitrogen (N), phosphorus (P), sodium (Na), potassium (K), and magnesium (Mg). While amelioration of salinity can be the result of secretion of osmolytes and the change in pH from salinity to neutrality. This inoculation also significantly improved the soil nutrients under salinity stress conditions. Inoculation of K. variicola SURYA6, resulted in more improved growth and nutrients contents in plants and enriched soil nutrients under salinity stress as compared to normal (non-saline) conditions. Such multifarious strain can serve as a potent bio-inoculant for growth promotion of wheat and maize in saline soil. However, multi-year field trials under different agro-climatic conditions are required to confirm the bio-efficacy of K. variicola SURYA6.

Halotolerant Plant Growth-Promoting Rhizobacteria Isolated From Saline Soil Improve Nitrogen Fixation and Alleviate Salt Stress in Rice Plants

“…The PGPR are known to ameliorate salt stress through the production of ACCD ( Sagar et al, 2020a , b ). Halophiles adapted to salt stress excrete a wide range of PGP metabolites ( Hamid et al, 2021 ; Khan et al, 2021 ) and various stress-tolerant enzymes ( Kusale et al, 2021b ). Sagar et al (2020a) reported the production of various PGP traits and ACCD in E.cloacae PR4.…”

Production, Purification, and Characterization of Bacillibactin Siderophore of Bacillus subtilis and Its Application for Improvement in Plant Growth and Oil Content in Sesame

“…Likewise, an increased carotenoids level was observed in siderophores producing strain (Ros2) treated to wheat plants in the presence of pesticide stress [70]. Kusale and co-workers [74] isolated a potential siderophores-producing organism from the rhizosphere; this bacterium treated to sesame plants showed a drastic increase in the seed germination, shoot, root length and also recorded enhanced levels of chlorophyll. Furthermore, in this study, the pH and electrical conductivity, NPK, and iron content in the soil are influenced by the presence of siderophores secreting microorganisms, this is in agreement with the results obtained by Kumar et al [75].…”

Halotolerant biofilm-producing rhizobacteria mitigate seawater-induced salt stress and promote growth of tomato

“…Furthermore, EPS-producing G. halophytocola KLBMP and Pantoea alhagi were reported to activate the antioxidant system, helping to withstand salt stress damage in crops 71 , 72 . Several studies also reported that PGPR producing IAA, ACC deaminase, catalase and acetoin alleviate the salinity stress in plants 1 , 29 , 60 , 73 – 75 . Our present study showed that the biofilm matrix and/or EPS contain several functional groups due to proteinacious curli, nanocellulose-rich polysaccharides lipids and nucleic acids.…”