Scrutinizes the Sustainable Role of Halophilic Microbial Strains on Oxygen-Evolving Complex, Specific Energy Fluxes, Energy Flow and Nitrogen Assimilation of Sunflower Cultivars in a Suboptimal Environment

Fiza Ali; Xiangying Wei; Zamin Shaheed Siddiqui; Jianjun Chen; Hafiza Hamna Ansari; Danish Wajid; Zafar Iqbal Shams; Muhammad Waseem Abbasi; Urooj Zafar

doi:10.3389/fpls.2022.913825

Scrutinizes the Sustainable Role of Halophilic Microbial Strains on Oxygen-Evolving Complex, Specific Energy Fluxes, Energy Flow and Nitrogen Assimilation of Sunflower Cultivars in a Suboptimal Environment

Front Plant Sci. 2022 Jul 18:13:913825. doi: 10.3389/fpls.2022.913825. eCollection 2022.

Authors

Fiza Ali¹, Xiangying Wei², Zamin Shaheed Siddiqui¹, Jianjun Chen³, Hafiza Hamna Ansari¹, Danish Wajid¹, Zafar Iqbal Shams⁴, Muhammad Waseem Abbasi⁵, Urooj Zafar⁶

Affiliations

¹ Department of Botany, Stress Physiology Phenomics Centre, University of Karachi, Karachi, Pakistan.
² Institute of Oceanography, Minjiang University, Fuzhou, China.
³ Environmental Horticulture Department and Mid-florida Research and Education Center, IFAS, University of Florida, Apopka, FL, United States.
⁴ Institute of Environmental Studies, University of Karachi, Karachi, Pakistan.
⁵ M.A.H. Qadri Biological Research Center, University of Karachi, Karachi, Pakistan.
⁶ Department of Microbiology, University of Karachi, Karachi, Pakistan.

Abstract

Environmental extremes such as hypersaline conditions are significant threats to agricultural productivity. The sustainable use of halophilic microbial strains was evaluated in plant in a salt stress environment. Oxygen-evolving complex (OEC), energy compartmentalization, harvesting efficiencies (LHE), specific energy fluxes (SEF), and nitrogen assimilation of oilseed crops (Sunflower cultivars) in a suboptimal environment was examined. Plants were grown in a plastic pot (15 ×18 cm²) containing sterilized (autoclaved at 120°C for 1 h) soil. Twenty-five ml suspension (10⁷ CFU/ml) each of Bacillus cereus strain KUB-15 and KUB-27 (accession number NR 074540.1) and Bacillus licheniformis strain AAB9 (accession number MW362506), were applied via drenching method. Month-old plants were subjected to salt stress via gradual increment method. The energy compartmentalization of microbial inoculated plants exposed to salt stress revealed higher photosystem II (PSII) activity at the donor side, lesser photo-inhibition, and increased performance of oxygen-evolving complex compared to control. High potassium (K⁺) and low sodium (Na⁺) ions in treated leaves with the activated barricade of the antioxidant system stimulated by Bacillus strains favored enhanced photochemical efficiency, smooth electron transport, and lesser energy dissipation in the stressed plants. Moreover, the results reveal the increased activity of nitrite reductase (NiR) and nitrate reductase (NR) by microbial inoculation that elevated the nitrogen availability in the salt-stressed plant. The current research concludes that the application of bio-inoculants that reside in the hyper-saline environment offers substantial potential to enhance salt tolerance in sunflowers by modulating their water uptake, chlorophyll, nitrogen metabolism, and better photochemical yield.

Keywords: bio-inoculation; energy; halotolerant microbial strains; light harvesting; photochemical efficiencies.