Gene Expression Analysis of Endophyte Infected and Uninfected Tall Fescue Under Water Stress

Tall fescue (Lolium arundinaceum) plants symbiotic with the endophytic fungus, Neotyphodium coenophialum (E+), have better survivability and persistence under stressful conditions, especially under drought stress, than plants lacking the endophyte (E-). To understand more about the grass-endophyte interactions and how endophyte affects the host plant physiology and gene expression, we conducted a time course water stress experiment in the greenhouse using genetically identical E+ and E- clone pairs of tall fescue.  Upon re-watering, survival and retillering was significantly greater for E+ than E- plants starting from days 2 - 3 of the stress conditions.  RNA-Seq analysis was done comparing E+ and E- on Day 2 stress and control plants.  Only a few genes were observed to be differentially expressed under the non-stressed conditions, but a large number of genes were differentially expressed under the water stress conditions.  In addition to genes involved in biotic  and abiotic stress response, genes in the jasmonic acid and amino acids derived from the shikimate biosynthetic pathways were also differentially expressed in Day 2 stress conditions.  Analysis of specific genes and pathways is ongoing and will be presented.