The Rhizobium-Legume Symbiosis: Co-opting Successful Stress Management

Abstract

The interaction of bacteria with plants can result in either a positive, negative, or neutral association. The rhizobium-legume interaction is a well-studied model system of a process that is considered a positive interaction. This process has evolved to require a complex signal exchange between the host and the symbiont. During this process, rhizobia are subject to several stresses, including low pH, oxidative stress, osmotic stress, as well as growth inhibiting plant peptides. A great deal of work has been carried out to characterize the bacterial response to these stresses. Many of the responses to stress are also observed to have key roles in symbiotic signaling. We propose that stress tolerance responses have been co-opted by the plant and bacterial partners to play a role in the complex signal exchange that occurs between rhizobia and legumes to establish functional symbiosis. This review will cover how rhizobia tolerate stresses, and how aspects of these tolerance mechanisms play a role in signal exchange between rhizobia and legumes.

Overview of biofertilizers in crop production and stress management for sustainable agriculture

“…Rhizobium and legume symbiosis is one of the most studied mutualistic relationships between plant root nodules and nitrogen-fixing microorganisms. Mutualistic relationships are initiated when the plant began to secrete the flavonoids and iso-flavonoids in its rhizosphere, where it is recognized by Rhizobium (Hawkins and Oresnik, 2022 ). It started to do infection by differentiating root hairs, developing infection thread up to the root hair cell where infectious thread releases all its bacteria in the cytoplasmic region.…”

The Role of Synthetic Microbial Communities (SynCom) in Sustainable Agriculture

“…In addition, microbial inoculants have the potential to suppress several pathogenic organisms (Yasmin et al, 2016;Olanrewaju et al, 2017;Abbasi et al, 2021). The main drawback of microbial application is that it often fails to yield consistent results because the plant-microbe association has not been considered with respect to various biotic and abiotic stress conditions that can affect the outcome (Finkel et al, 2017;de Souza et al, 2020;Hawkins & Oresnik, 2022). For inoculums to be successful in the field, an in-depth knowledge of microbial abundance, diversity, as well as plant-microbe interactions, is essential to be able to predict overall functionality (Chodkowski and Shade, 2017).…”

Scent of a Symbiont: The Personalized Genetic Relationships of Rhizobium—Plant Interaction

“…This process facilitates the accommodation of rhizobia inside the plant cell, where they differentiate into bacteroids and start fixing atmospheric nitrogen [ 12 ]. Metabolic rewiring and the stress response play crucial roles in symbiotic establishment [ 13 , 14 ], since bacteroids must cope with osmotic stress, changes in pH, reduced oxygen tension [ 14 ] and plant peptides. Plant peptides are becoming increasingly relevant since they induce and maintain growth inhibition and can modify host compatibility [ 15 , 16 , 17 , 18 , 19 ].…”