Bacillus licheniformis FMCH001 Increases Water Use Efficiency via Growth Stimulation in Both Normal and Drought Conditions.

Saqib Saleem Akhtar,Fulai Liu,Renate Müller,Thomas Roitsch,Lars Moelbak,Daniel Buchvaldt Amby,Jesper Cairo Westergaard,Lorenzo Fimognari,Dominik K Großkinsky,Josefine Nymark Hegelund

doi:10.3389/fpls.2020.00297

Abstract

Increasing agricultural losses due to biotic and abiotic stresses caused by climate change challenge food security worldwide. A promising strategy to sustain crop productivity under conditions of limited water availability is the use of plant growth promoting rhizobacteria (PGPR). Here, the effects of spore forming Bacillus licheniformis (FMCH001) on growth and physiology of maize (Zea mays L. cv. Ronaldinho) under well-watered and drought stressed conditions were investigated. Pot experiments were conducted in the automated high-throughput phenotyping platform PhenoLab and under greenhouse conditions. Results of the PhenoLab experiments showed that plants inoculated with B. licheniformis FMCH001 exhibited increased root dry weight (DW) and plant water use efficiency (WUE) compared to uninoculated plants. In greenhouse experiments, root and shoot DW significantly increased by more than 15% in inoculated plants compared to uninoculated control plants. Also, the WUE increased in FMCH001 plants up to 46% in both well-watered and drought stressed plants. Root and shoot activities of 11 carbohydrate and eight antioxidative enzymes were characterized in response to FMCH001 treatments. This showed a higher antioxidant activity of catalase (CAT) in roots of FMCH001 treated plants compared to uninoculated plants. The higher CAT activity was observed irrespective of the water regime. These findings show that seed coating with Gram positive spore forming B. licheniformis could be used as biostimulants for enhancing plant WUE under both normal and drought stress conditions.

Highlights

Changing climatic conditions due to global warming pose severe environmental stresses to crops, which affect their growth and yield
In experiments P1 and P3, moderate drought regimes (65% field capacity (FC)) caused a reduction in shoot dry weight (DW) compared to plants grown under well-watered conditions (Table 1)
The root to shoot ratio was higher for well-watered plants with FMCH001 in P1 experiments compared to controls

Summary

Introduction

Changing climatic conditions due to global warming pose severe environmental stresses to crops, which affect their growth and yield. Among these stresses, drought is considered the single most devastating environmental stress, which decreases crop productivity more than any other environmental stress (Farooq et al, 2009). Drought stress induces reactive oxygen species (ROS) such as superoxide radicals, hydrogen peroxide, and hydroxyl radicals resulting in oxidative stress (Noctor et al, 2014). ROS can cause damage to various levels of organization, e.g., initiate lipid peroxidation, membrane deterioration, and degradation of proteins, lipids, and nucleic acids in plants (Sgherri et al, 2000; Hendry, 2008; Nair et al, 2008). The results of these strategies are slow to implement in the field and require significant economic and technical investments

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