Symbiogenics: An Epigenetic Approach to Mitigating Impacts of Climate Change on Plants

Abstract

We have found that plants in natural ecosystems adapt to abiotic stress by forming symbiotic associations with Class 2 fungal endophytes. Without the endophytes, plants are not stress-tolerant and do not survive in the habitats to which they are adapted. Symbiotically conferred stress tolerance typically occurs in a habitat-specific manner and is based on interactions between environmental factors and both plant and fungal genomes. For example, endophytes from geothermal plants confer heat tolerance, and endophytes from coastal plants confer salt tolerance. We have designated this phenomenon as habitat-adapted symbiosis and hypothesize that it is a ubiquitous aspect of plant ecology. Class 2 endophytes also increase plant growth and development while decreasing water consumption. We present metabolic and gene expression data to support a working model for the underlying mechanisms of endophyte-conferred benefits to plants. Although endophytes had no effect on photosynthetic rate and metabolic efficiency, they significantly increased photosynthetic efficiency. Endophytes significantly altered the ratio of upregulated to downregulated (UR:DR genes) plant genes compared with nonsymbiotic plants. Specific UR:DR gene ratios varied with endophyte species as well as habitat of origin. Collectively, these observations have allowed us to design a new symbiogenic (symbio = symbiosis; genic = gene influence) strategy for mitigating impacts of climate change on crop production.