Endophyte-host associations in grasses. XVIII. Moisture relations and insect herbivory of the emergent stromal leaf of Epichloe

Experiments indicate that transpiration is enhanced in stromal leaves. The stromal leaf has been anatomically modified so that evaporation of water from its surface is increased and unregulatable by the plant. The biological role of the stromal leaf may be to draw water through the stroma to replace evaporative loss from the stromal mycelium. Herbivory studies indicate that the stromal leaf is chemically altered to deter herbivory. Enhanced insect resistance and drought tolerance in grasses with nonstroma-forming endophytes, that are believed to have evolved from Epichloe, are characteristics that may have been preadapted by the need for Epichloe to alter the stromal leaf and defend it from herbivory. -from Authors