Plant-microbe interactions

Abstract

Globally, the majority of nitrogen and phosphorus uptake by plants is mediated by mutualistic root microbes, which form intricate and complex biochemical and genetic interactions with plants. Plant leaves host a variety of beneficial bacteria and fungi that contribute to plant nutrition and/or defense against pathogens. In addition to mutualistic bacteria intimately associated with roots, there exist plant growth-promoting rhizobacteria more loosely associated with roots that contribute to plant nutrition, protection from pathogens, and environmental stress reduction. The region surrounding roots, the rhizosphere, is a dynamic environment, rich in chemical communication among plants and microbes, where nutrient cycling is altered by root exudation and heightened microbial activity. Plants profoundly impact the biogeochemical cycling activities of soil microbes through their effects on microclimate and soil chemistry. Plants and microbes collaborate to produce soil organic matter such as humic substances, which determine important soil properties such as water and nutrient holding capacity and the stability of soil carbon. The species composition of plant-associated microbial communities is extremely diverse and variable, but is strongly influenced by plant species. Soil microbial communities can mediate changes in plant diversity during invasions or succession through positive and negative soil feedbacks. Plant-microbe interactions are involved in several feedback mechanisms in which the biosphere reacts to and influences climate change. There are currently gaps in the understanding of plant-microbe interactions, particularly in terms of genetics of certain plant-microbe mutualisms, the diversity of plant-associated microbial communities, and the role of plant-microbe interactions in producing feedbacks to climate change, however, new technologies are emerging that should help fill existing gaps.