Rhizosphere plant-microbe interactions under water stress

Authors: BHATTACHARYYA, ANKITA - University Of Southern Mississippi; PABLO, CLINT - University Of Southern Mississippi; MAVRODI, OLGA - University Of Southern Mississippi; Weller, David; Thomashow, Linda; MAVRODI, DMITRI - University Of Southern Mississippi

Submitted to: Advances in Applied Microbiology
Publication Type: Literature Review
Publication Acceptance Date: 4/16/2021
Publication Date: 4/16/2021
Citation: Bhattacharyya, A., Pablo, C.D., Mavrodi, O.V., Weller, D.M., Thomashow, L.S., Mavrodi, D.V. 2021. Rhizosphere plant-microbe interactions under water stress . Advances in Applied Microbiology. 115,2021,65-113. https://doi.org/10.1016/bs.aambs.2021.03.001.
DOI: https://doi.org/10.1016/bs.aambs.2021.03.001

Interpretive Summary: Climate change, with its extreme temperature, weather and precipitation patterns, is a major global concern of dryland farmers, who currently meet the challenges of climate change agronomically and with growth of drought-tolerant crops. Plants themselves compensate for water stress by modifying above-ground surfaces to reduce water loss through the foliage and by increasing water uptake through the roots. These responses are complemented by metabolic changes involving hormone-mediated activation of stress response pathways, resulting in decreased photosynthetic activity and the accumulation of metabolites to help maintain water relations in plant tissues. Diverse microbial communities sustained by plants contribute to host drought tolerance by adjusting planthormone levels on the roots and producing water-sequestering biofilms. Drylands of the Inland Pacific Northwest, USA, illustrate the interdependence of dryland crops and their associated microbes. Indigenous Pseudomonas spp. selected there by long-term wheat monoculture suppress root diseases via the production of antibiotics, with soil moisture a critical determinant of the bacterial distribution, dynamics and activity. Those pseudomonads producing phenazine antibiotics on wheat had more abundant rhizosphere biofilms and provided improved tolerance to drought, suggesting a role of the antibiotic in alleviation of drought stress. The genetic, physiological and biochemical studies suggest the importance of wheat root exudate-derived compounds for the adaptation of these bacteria to the root-associated lifestyle and support the idea that the exchange of metabolites between plant roots and microorganisms profoundly affects and shapes the belowground plant microbiome under water stress.

Technical Abstract: Climate change, with its extreme temperature, weather and precipitation patterns, is a major global concern of dryland farmers, who currently meet the challenges of climate change agronomically and with growth of drought-tolerant crops. Plants themselves compensate for water stress by modifying aerial surfaces to control transpiration and altering root hydraulic conductance to increase water uptake. These responses are complemented by metabolic changes involving phytohormone network-mediated activation of stress response pathways, resulting in decreased photosynthetic activity and the accumulation of metabolites to maintain osmotic and redox homeostasis. Phylogenetically diverse microbial communities sustained by plants contribute to host drought tolerance by modulating phytohormone levels in the rhizosphere and producing water-sequestering biofilms. Drylands of the Inland Pacific Northwest, USA, illustrate the interdependence of dryland crops and their associated microbiota. Indigenous Pseudomonas spp. selected there by long-term wheat monoculture suppress root diseases via the production of antibiotics, with soil moisture a critical determinant of the bacterial distribution, dynamics and activity. Those pseudomonads producing phenazine antibiotics on wheat had more abundant rhizosphere biofilms and provided improved tolerance to drought, suggesting a role of the antibiotic in alleviation of drought stress. The transcriptome and metabolome studies suggest the importance of wheat root exudate-derived osmoprotectants for the adaptation of these pseudomonads to the rhizosphere lifestyle and support the idea that the exchange of metabolites between plant roots and microorganisms profoundly affects and shapes the belowground plant microbiome under water stress.