Plant Probiotics for Nutrient Acquisition by Agriculturally Important Grasses: A Comprehensive Review of the Science and the Application

Abstract

Intensification of agricultural land and the overuse of inorganic fertilisers has led to soil acidification, depletion of organic matter, and environmental pollution. Approaches to protect soil health, including the enhancement of microbial diversity, are integral to improving crop productivity and food security. Metagenomics has rapidly improved our understanding of soil microbial diversity and function, while genetic techniques have helped to dissect the complex signal exchange between microorganisms and plants. This article presents and evaluates reported beneficial effects of plant growth‐promoting bacteria (PGPB), focussing on those capable of mobilising or solubilising nutrients and/or stimulating plant growth when applied to agriculturally important grasses. The agricultural industry has capitalised on these scientific advancements, generating microbial formulations for specific crop responses. However, scientific methodologies must be applied in order to overcome inherent limitations of many PGPBs including their inability to be cultured, their poorly defined or multiple modes of action, a low level of integration with the crop partner, and an unpredictability in translating beneficial plant responses to the field. Novel approaches such as engineered rhizospheres, enhancing endophytic systems, cereal nodule development, and the use of inoculant consortiums will be necessary to sustain growth in the biofertiliser industry.

Is phosphate solubilizing ability in plant growth‐promoting rhizobacteria isolated from chickpea linked to their ability to produce ACC deaminase?

“…These bacteria facilitate P solubilization through secretion of low molecular weight carboxylates and protons (H + ) that ultimately result in localized acidification (Khan et al 2013). PSB that enhance plant growth through P solubilization are referred to as plant growth-promoting rhizobacteria (PGPR) (Swift et al 2018;Alemneh et al 2020). In some instances, PGPR unable to solubilize P nevertheless can increase P concentration in various plant species (Barnawal et al 2012(Barnawal et al , 2014Chandra et al 2019), through expression of 1-aminocyclopropane-1-carboxylate (ACC) deaminase.…”