The Coevolution of Plants and Microbes Underpins Sustainable Agriculture

Abstract

Terrestrial plants evolution occurred in the presence of microbes, the phytomicrobiome. The rhizosphere microbial community is the most abundant and diverse subset of the phytomicrobiome and can include both beneficial and parasitic/pathogenic microbes. Prokaryotes of the phytomicrobiome have evolved relationships with plants that range from non-dependent interactions to dependent endosymbionts. The most extreme endosymbiotic examples are the chloroplasts and mitochondria, which have become organelles and integral parts of the plant, leading to some similarity in DNA sequence between plant tissues and cyanobacteria, the prokaryotic symbiont of ancestral plants. Microbes were associated with the precursors of land plants, green algae, and helped algae transition from aquatic to terrestrial environments. In the terrestrial setting the phytomicrobiome contributes to plant growth and development by (1) establishing symbiotic relationships between plant growth-promoting microbes, including rhizobacteria and mycorrhizal fungi, (2) conferring biotic stress resistance by producing antibiotic compounds, and (3) secreting microbe-to-plant signal compounds, such as phytohormones or their analogues, that regulate aspects of plant physiology, including stress resistance. As plants have evolved, they recruited microbes to assist in the adaptation to available growing environments. Microbes serve themselves by promoting plant growth, which in turn provides microbes with nutrition (root exudates, a source of reduced carbon) and a desirable habitat (the rhizosphere or within plant tissues). The outcome of this coevolution is the diverse and metabolically rich microbial community that now exists in the rhizosphere of terrestrial plants. The holobiont, the unit made up of the phytomicrobiome and the plant host, results from this wide range of coevolved relationships. We are just beginning to appreciate the many ways in which this complex and subtle coevolution acts in agricultural systems.

Uncovering New Insights and Misconceptions on the Effectiveness of Phosphate Solubilizing Rhizobacteria in Plants: A Meta-Analysis

“…A major constraint in the transition from aquatic to terrestrial plant life, was the inadequate water and nutrient supply. To meet these requirements and facilitate nutrient acquisition, plants engaged in symbiotic relationships with soil microorganisms such as PSB ( Lyu et al, 2021b ). The co-evolution between a plant and its microbiome has led to a highly structured rhizosphere characterized by an interactive rhizobiome, in which cross-kingdom communication results in improved performance for both partners ( Wallenstein, 2017 ).…”

Recent Developments in the Study of Plant Microbiomes

“…The vision of the plant as an holobiont is represented by an incredibly intricate net of interactions connecting the plant host with its endocellular and extracellular microbiome and, of course all the members of the microbiota to each other. In such a complex web of relationships, each variation in the microbiome determines shifts in the net of interactions amongst all the organisms involved [ 144 ]. However, the recent concept of the core microbiome, highlighted the occurrence of “sets of microorganisms that form cores of interactions that can be used to optimize microbial functions at the individual plant and ecosystem levels” [ 145 ].…”

Plant Responses to Biotic Stress: Old Memories Matter

“…Terrestrialisation is an impactful stress that readily affects the “evo-physio” of all land plants [ 29 ]. The physiological alterations impacted by microbes include the development of symbionts, endosymbionts, biocontrol agents and non-host resistance responses [ 30 ]. As discussed earlier, the plant–pathogen interaction largely depends on the successful interaction of specific microbes with the cognate receptors present on the host surface called “recognition reaction”.…”

“…The identification and orchestration of pathogenic response by specific receptors strongly depend on plants’ memory against the repertoire of pathogenic microbes. Unlike animals, no specialised mobile defender cells have been identified in plants [ 30 ], although many signalling components may substitute immunogenic memory cells. Extracellular and intracellular receptors have contributed to the first line of immune memory.…”