The Impact of Beneficial Plant-Associated Microbes on Plant Phenotypic Plasticity

Abstract

Plants show phenotypic plasticity in response to changing or extreme abiotic environments; but over millions of years they also have co-evolved to respond to the presence of soil microbes. Studies on phenotypic plasticity in plants have focused mainly on the effects of the changing environments on plants’ growth and survival. Evidence is now accumulating that the presence of microbes can alter plant phenotypic plasticity in a broad range of traits in response to a changing environment. In this review, we discuss the effects of microbes on plant phenotypic plasticity in response to changing environmental conditions, and how this may affect plant fitness. By using a range of specific plant-microbe interactions as examples, we demonstrate that one way that microbes can alleviate the effect of environmental stress on plants and thus increase plant fitness is to remove the stress, e.g., nutrient limitation, directly. Furthermore, microbes indirectly affect plant phenotypic plasticity and fitness through modulation of plant development and defense responses. In doing so, microbes affect fitness by both increasing or decreasing the degree of phenotypic plasticity, depending on the phenotype and the environmental stress studied, with no clear difference between the effect of prokaryotic and eukaryotic microbes in general. Additionally, plants have the ability to modulate microbial behaviors, suggesting that they manipulate bacteria, enhancing interactions that help them cope with stressful environments. Future challenges remain in the identification of the many microbial signals that modulate phenotypic plasticity, the characterization of plant genes, e.g. receptors, that mediate the microbial effects on plasticity, and the elucidation of the molecular mechanisms that link phenotypic plasticity with fitness. The characterization of plant and microbial mutants defective in signal synthesis or perception, together with carefully designed glasshouse or field experiments that test various environmental stresses will be necessary to understand the link between molecular mechanisms controlling plastic phenotypes with the resulting effects on plant fitness.

Host plant quality mediates competition between arbuscular mycorrhizal fungi

“…This environmental variability affects the plants themselves, but also their symbiotic partners, such as AMF. Microbes have to cope and adapt to hosts that vary in the benefits they provide (Goh et al 2013, Zheng et al 2014. In this study we directly assessed how varying host quality affects competition between two arbuscular mycorrhizal fungi.…”

Engineering Microbiomes to Improve Plant and Animal Health

“…Microbiomes of animals and plants are often dominated by eubacteria, but fungi, protozoa, archaea, and viruses also can play important roles in these communities [1][2][3][4][5]. Microbiomes are not passive players [6,7]; rather, microbes can alter host development, physiology, and systemic defenses [2,8,9], enable toxin production and disease resistance [10,11], increase host tolerance to stress and drought [12][13][14], modulate niche breadth [15], and change fitness outcomes in host interactions with competitors, predators, and pathogens [6]. Because microbiomes can encompass a hundred-fold more genes than host genomes [16], and because this 'hologenome' of a hostmicrobiome association can vary over space and time [17,18], microbiomes can function as a phenotypically plastic buffer between the host-genotype's effects and the environmental effects that interact to shape host phenotypes.…”

Reviving of the endophytic bacterial community as a putative mechanism of plant resistance

“…Such information-processing networks belong to the systems biology concept and represent current conceptual perspective of living organisms (Shapiro 2010). Microbes directly or indirectly affect plant plasticity (Goh et al 2013). There is limited knowledge about microbial factors acting directly on the plant information-processing networks (Muñoz Bodnar et al 2012;Pirttilä et al 2004).…”