Jf. White et Cr. Camp, A STUDY OF WATER RELATIONS OF EPICHLOE-AMARILLANS WHITE, AN ENDOPHYTEOF THE GRASS AGROSTIS-HIEMALIS (WALT) BSP, Symbiosis, 18(1), 1995, pp. 15-25
In this study we measured water losses from various excised parts of p
lants of Agrostis hiemalis and stromata of the endosymbiont fungus Epi
chloe amarillans. Measurements were made by excising culms from plants
, then inserting cut ends into microsedimentation tubes containing wat
er and measuring water consumed under defined conditions. It was found
that water was lost from the stroma at a rate 10 times faster than th
at from the surface of the emergent leaf blade. Comparative studies of
stroma-bearing culms with those free of stromata showed that overall
water losses in stroma-bearing culms were only slightly higher than wa
ter losses in culms without stromata. However, it was found that strom
a-bearing culms were significantly reduced in mass when compared to cu
lms free of stromata. This mass reduction is suggested to have a compe
nsatory effect on water losses. It is suggested that the enhanced rate
and unregulatability of the evaporation of water from stromata may ha
ve been a key factor in selecting for endophytes that do not produce s
tromata.