FE-SEM/EDX Based Zinc Mobilization Analysis of Burkholderia cepacia and Pantoea rodasii and Their Functional Annotation in Crop Productivity, Soil Quality, and Zinc Biofortification of Paddy

Abstract

The experimental study was contrived to characterize two zinc-solubilizing bacteria (ZSB), namely BMRR126 and BMAR64, and their role in zinc (Zn) biofortification of rice. These bacteria solubilized Zn profoundly, determined qualitatively by halo-zone formation on a solid medium and quantitatively in a liquid broth by AAS and SEM-EDX. The lowering of pH and contact angle assessment of the liquid broth unveiled the establishment of the acidic conditions in a medium suitable for Zn solubilization. The characterization of both isolates on the basis of 16S rRNA gene analysis was identified as Burkholderia cepacia and Pantoea rodasii, respectively. These strains were also found to have some plant probiotic traits namely phosphate solubilization, production of siderophore, indole acetic acid (IAA), exopolysaccharide (EPS), and ammonia. The field experiments were performed at two diverse locations and under all treatments; the simultaneous use of BMRR126 and BMAR64 with zinc oxide (ZnO) resulted in the highest growth and productivity of the paddy crop. The utmost Zn achievement in the grain was estimated in a treatment (T9) (25.07 mg/kg) containing a consortium of BMRR126 and BMAR64 along with ZnO for the Terai region. The treatment containing single ZSB bioinoculant BMRR126 (T7) showed an elevated Zn amount in the rice grain (33.25 mg/kg) for the Katchar region. The soil parameters (pH, EC, organic carbon, NPK, available Zn, and dehydrogenase activity) were also positively influenced under all bacterial treatments compared to the uninoculated control. Our study clearly accentuates the need for Zn solubilizing bacteria (ZSB) to provide the benefits of Zn-biofortification in different regions.

Contemplating the role of zinc-solubilizing bacteria in crop biofortification: An approach for sustainable bioeconomy

“…Various countries, such as India, Iran, Pakistan, Turkey, and China, have a vast area of zinc-deficient soil and present a valid reason to induce the consequences of zinc dearth in the human population of these specific regions (Cakmak and Kutman, 2018;Upadhayay et al, 2019). Furthermore, inadequate zinc solubility in the soil is a major reason for the onset of zinc deficiency in crops (Upadhayay et al, 2018;Upadhayay et al, 2019;Upadhayay et al, 2022b).…”

“…Various biofortification strategies have been described to counteract micronutrient malnutrition (Hussain et al, 2018;Upadhayay et al, 2018). The concept of biofortification is a suitable way to biofortify crops with elevated concentrations of micronutrients such as zinc, iron, and selenium (Kamran et al, 2017;Upadhayay et al, 2018;Upadhayay et al, 2022a;Upadhayay et al, 2022b). Selective biofortification strategies include an agronomic approach, genetic engineering, plant breeding, and the application of biostimulants (plant growthpromoting bacterial inoculants) (Upadhayay et al, 2018;Khan et al, 2019;Upadhayay et al, 2022a).…”

“…The use of ZSB, having numerous plant growth-promoting properties, presents a new strategic plan for developing biofortified crops in an eco-friendly manner (Upadhayay et al, 2022a). The remarkable zinc solubilization behavior and plant growth-stimulating properties of a bacterial strain tested under in vitro settings make it a suitable bio-inoculant for increasing the zinc content in plants (Vaid et al, 2014;Kamran et al, 2017;Upadhayay et al, 2022a;Upadhayay et al, 2022b). Upadhayay et al (2022b) illustrated the solubilization behavior of the insoluble form of Zn (ZnO) in solid and liquid media under laboratory settings.…”

“…The zinc (Zn) deficiency problem in food crops can be addressed through the zinc biofortification approach to provide adequate zinc content in multiple edible parts of plants (Upadhayay et al, 2022a;Upadhayay et al, 2022b). Plant zinc uptake sometimes drops due to adverse environmental factors, resulting in reduced plant growth.…”

“…The use of zinc-solubilizing bacteria with diverse abilities to promote plant growth is the current need to increase crop productivity and food security (Hussain et al, 2018). A few studies have explored the outstanding ability of zinc-solubilizing bacteria (ZSB) to increase the zinc concentration in the edible parts of crops (Moreno-Lora et al, 2019;Bhatt and Maheshwari, 2020;Mumtaz et al, 2020;Verma et al, 2020;Bashir et al, 2021;Jalal et al, 2021;Karnwal, 2021;Kushwaha et al, 2021;Upadhayay et al, 2022a;Upadhayay et al, 2022b). The use of agrochemicals has led to (a) a loss of soil fertility, (b) risks to human health, (c) an imbalance in the environment, (d) a change in soil ecology, etc.…”