Root Exudates: Mechanistic Insight of Plant Growth Promoting Rhizobacteria for Sustainable Crop Production

Abstract

The breaking silence between the plant roots and microorganisms in the rhizosphere affects plant growth and physiology by impacting biochemical, molecular, nutritional, and edaphic factors. The components of the root exudates are associated with the microbial population, notably, plant growth-promoting rhizobacteria (PGPR). The information accessible to date demonstrates that PGPR is specific to the plant's roots. However, inadequate information is accessible for developing bio-inoculation/bio-fertilizers for the crop in concern, with satisfactory results at the field level. There is a need to explore the perfect candidate PGPR to meet the need for plant growth and yield. The functions of PGPR and their chemotaxis mobility toward the plant root are triggered by the cluster of genes induced by the components of root exudates. Some reports have indicated the benefit of root exudates in plant growth and productivity, yet a methodical examination of rhizosecretion and its consequences in phytoremediation have not been made. In the light of the afore-mentioned facts, in the present review, the mechanistic insight and recent updates on the specific PGPR recruitment to improve crop production at the field level are methodically addressed.

Potential of plant growth promoting bacterial consortium for improving the growth and yield of wheat under saline conditions

“…These beneficial bacteria including plant growth promoting rhizobacteria (PGPR) have been widely reported to help crop plants in various kinds of stresses under varying environmental conditions ( Khan et al, 2013 ; Raza et al, 2021 ; Nadeem et al, 2022 ; Rafique et al, 2022 ). These PGPR protect the plant from the negative impact of salinity through a number of their direct and indirect mechanisms and therefore enable it to withstand stress environment ( Zahir et al, 2009 , 2019 ; Fu et al, 2010 ; Glick, 2013 ; Nadeem et al, 2016 ; Ullah et al, 2017 ; Al-Barakah and Sohaib, 2019 ; Rafique et al, 2021 ; Saeed et al, 2021 ; Singh P. et al, 2022 ; Upadhyay and Chauhan, 2022 ; Upadhyay et al, 2022 ). However, under certain stresses, the results obtained in axenic conditions could not be reproduced in the field ( Smyth et al, 2011 ).…”

The plasma membrane-localized OsNIP1;2 mediates internal aluminum detoxification in rice

“…Under adverse conditions, plant roots secrete various metabolites into the rhizosphere. The root exudates could adjust soil pH to solubilize mineral nutrients and make them more accessible to plants; chelate toxic compounds; facilitate the formation of beneficial microbiota communities, or function as toxic compounds for pathogens ( Bertin et al, 2003 ; Bais et al, 2006 ; Badri and Vivanco, 2009 ; Baetz and Martinoia, 2014 ; Zhao et al, 2019 ; Vives-Peris et al, 2020 ; Upadhyay et al, 2022 ). For instance, under Al toxicity, plant roots secrete various organic acids (OAs), i.e., malate, citrate, and oxalate, into the rhizosphere ( Sasaki et al, 2004 ; Magalhaes et al, 2007 ; Liu et al, 2009 , 2012 ; Matonyei et al, 2014 ; Kochian et al, 2015 ; Qiu et al, 2019 ).…”

Enhancing Mechanisms of the Plant Growth-Promoting Bacterial Strain Brevibacillus sp. SR-9 on Cadmium Enrichment in Sweet Sorghum by Metagenomic and Transcriptomic Analysis

“…In addition, plants have different coping mechanisms to different environments and secrete a large number of compounds that may require transporters, which accumulate in plant roots and exude into the rhizosphere microbiome. For example, ABC transporters are involved in many biological functions, including bacterial resistance, pheromone secretion, mitochondrial biological function, and heavy metal detoxification [ 46 ]. In this study, the metabolic pathways that were significantly different in the untreated group included ABC transporter, beta-lactam resistance, and degradation of aromatic compounds, which may be due to the interaction between sweet sorghum and rhizosphere microorganisms to adapt to environmental stress.…”