Seed Endophyte bacteria enhance drought stress tolerance in Hordeum vulgare by regulating, physiological characteristics, antioxidants and minerals uptake

Zainul Abideen; Massimiliano Cardinale; Faisal Zulfiqar; Hans-Werner Koyro; Sarwat Ghulam Rasool; Kamel Hessini; Walid Darbali; Fengliang Zhao; Kadambot H M Siddique

doi:10.3389/fpls.2022.980046

Seed Endophyte bacteria enhance drought stress tolerance in Hordeum vulgare by regulating, physiological characteristics, antioxidants and minerals uptake

Front Plant Sci. 2022 Oct 5:13:980046. doi: 10.3389/fpls.2022.980046. eCollection 2022.

Authors

Affiliations

¹ Dr. Muhammad Ajmal Khan Institute of Sustainable Halophyte Utilization, University of Karachi, Karachi, Pakistan.
² Institute of Plant Ecology, Research Centre for Bio Systems, Land Use, and Nutrition (IFZ), Justus-Liebig-University Giessen, Giessen, Germany.
³ Institute of Applied Microbiology, Research Centre for Bio Systems, Land Use, and Nutrition (IFZ), Justus-Liebig-University Giessen, Giessen, Germany.
⁴ Department of Biological and Environmental Sciences and Technologies (DiSTeBa), University of Salento, Lecce, Italy.
⁵ Department of Horticultural Sciences, Faculty of Agriculture and Environment, The Islamia University of Bahawalpur, Bahawalpur, Pakistan.
⁶ Department of Biology, College of Sciences, Taif University, Taif, Saudi Arabia.
⁷ Environment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Science (CATAS), Haikou, China.
⁸ The UWA Institute of Agriculture, The University of Western Australia, Perth, WA, Australia.

Abstract

Growth stimulating bacteria help remediate dry arid soil and plant stress. Here, Pseudomonas sp. and Pantoea sp. we used to study the stress ecology of Hordeum vulgare and the environmental impact of water deficit on soil characteristics, growth, photosynthesis apparatus, mineral acquisition and antioxidiant defense. Plants inoculated with Pseudomonas or Pantoea had significantly higher (about 2 folds) soil carbon flux (soil respiration), chlorophyll levels (18%), net photosynthetic rate (33% in Pantoea and 54% in Pseudomonas), (44%) stomatal conductance than uninoculated plants in stressed conditions. Both bacterial strains improved leaf growth (23-29%) and root development under well-watered conditions but reduced around (25%) root biomass under drought. Plants inoculated with Pseudomonas or Pantoea under drought also increased of about 27% leaf respiration and transpiration (48%) but decreased water use efficiency, photoinhibition (91%), and the risk of oxidative stress (ETR/A) (49%). Drought stress increased most of the studied antioxidant enzymatic activities in the plants inoculated with Pseudomonas or Pantoea, which reduce the membrane damage and protect plants form oxidative defenses. Drought stress increased K⁺ acquisition around 50% in both shoots inoculated with Pseudomonas or Pantoea relative to non-stressed plants. Plants inoculated with Pseudomonas or Pantoea increased shoot Na⁺ while root Na⁺ only increased in plants inoculated with Pseudomonas in stressed conditions. Drought stress increased shoot Mg²⁺ in plants inoculated with Pseudomonas or Pantoea but did not affect Ca²⁺ relative to non-stressed plants. Drought stress increased about 70% K⁺/Na⁺ ratio only in plants inoculated with Pseudomonas relative to non-stressed plants. Our results indicate that inoculating barley with the studied bacterial strains increases plant biomass and can therefore play a role in the environmental remediation of drylands for food production.

Keywords: bacterial inoculation; ecophysiology; endophyte (DSE); oxidative stress; photosynthesis.