Endophyte-infection reduces leaf dehydration of ryegrass and tall fescue plants under moderate water deficit

Abstract

Drought stress is one of the limiting factors in perennial ryegrass growth and development. In order to investigate the drought responses among different cultivars and evaluate the role of fungal endophyte in modifying drought responses, a glasshouse experiment was conducted using ryegrass cultivars 'Alto' and 'Banquet II', and a Mediterranean tall fescue cultivar, 'Grasslands Flecha' as contrast with the two ryegrass cultivars. Under drought stress 'Flecha' had a higher stomatal conductance and transpiration rate than the two ryegrass cultivars, and also significantly greater deeproot allocation. Endophyte-infected plants exhibited reduced leaf dehydration under stress compared with endophyte-free plants. Under stress, endophyte-free plants displayed significantly lower relative water content and a more negative leaf water potential and osmotic potential than well-watered endophyte-free plants, whereas endophyte-infected plants displayed smaller and non-significant changes when subjected to water deficit stress. Endophyte-infected plants also had less deep-root allocation than endophyte-free plants. The results of this study increase understanding of the relationship between endophytes and their ryegrass or tall fescue hosts under drought stress. Keywords: deep-root allocation, Epichloë, gas exchange parameters, Neotyphodium, plant water relations, Lolium perenne