Plant-microbe interactions: mechanisms and applications for improving crop yield and quality

Abstract

In light of the dual challenges posed by climate change and the burgeoning global population, which are putting food security at risk, there is an urgent need to develop sustainable agricultural innovations. These innovations must be capable of increasing crop productivity and maintaining soil health, reducing our dependence on synthetic agrochemical inputs, and preserving the nutritional quality of our food crops. It is crucial to delve into the biological and physiological processes that underlie plant-microbe interactions. Such knowledge is paramount in harnessing the advantages of these interactions for sustainable agriculture. This review delves into the intricate mechanisms through which beneficial rhizosphere and soil bacteria, known as plant growth-promoting bacteria (PGPB), contribute to enhancing crop yields, bolstering stress resilience, and improving the nutritional quality of crops. We explore the vital capabilities of PGPB, encompassing nitrogen fixation, phosphorus solubilization, iron chelation through microbial siderophores, and modulation of hormonal signaling pathways. The PGPB taxa in focus include rhizobial diazotrophs (genera Rhizobium, Bradyrhizobium) and diverse heterotrophic genera (Azotobacter, Bacillus, Pseudomonas). Recent studies have provided compelling evidence of the effectiveness of PGPB in biofortification interventions, which involve enriching essential micronutrients in crops through microbial enhancement of nutrient mobilization, uptake, translocation, and acquisition. Understanding the genomic and metabolic mechanisms that govern plant growth promotion, abiotic stress tolerance, pathogen inhibition, and biofortification by PGPR is pivotal. Such insights can inform endeavors to optimize, formulate, and apply tailored PGPR inoculants. Adopting a systems perspective that acknowledges the intricate interactions among plants, microbes, and soil in this context is essential. Furthermore, we advocate for continued research in various domains, including microbiota recruitment, PGPR screening, the cumulative effects of various approaches, developing effective delivery systems, field testing, and integrating these findings with breeding programs. Interdisciplinary collaboration among microbial ecologists, plant physiologists, crop scientists, and farmers will be instrumental in unlocking the full potential of plant-microbe associations to ensure sustainable agriculture and food crop quality. In summary, more profound insights into PGPB biology and their interactions with plants offer a promising path toward enhancing productivity and sustainability in the face of escalating demands.