Ergovaline and peramine production in endophyte-infected tall fescue: Independent regulation and effects of plant and endophyte genotype.

Peramine and ergovaline have ecological and economical significance because they possess insect and/or mammalian toxicity properties. The relationship between these endophytically derived alkaloids in tall fescue (Festuca arundinacea Schreb.) is unknown. Seasonal and plant tissue effects on the concentration of peramine and ergovaline was investigated in field and greenhouse experiments. The relationship between the alkaloids and the regulatory effects of endophyte and plant on their content were investigated among progeny of reciprocal crosses between high- and low-ergovaline and peramine plant-endophyte combinations. Variation in peramine concentration ranged from 750 to 1742 µg/kg in greenhouse-grown plants, and there was no seasonal trend in peramine content. There was a correlation (r=0.69) between peramine and ergovaline content among leaf tissues of field-grown plants, but there was no correlation between the alkaloids in the culm (r=0.20) or panicle (r=0.17) tissues. Mean leaf ergovaline concentration of progeny derived from the low-ergovaline parent (163 µg/kg) was less than the midparent value (228 µg/kg), but mean of progeny from the high-ergovaline parent was not different from the mid-parent value. Ranges within each progeny set were approximately double their mean. Mean leaf peramine concentrations of the progeny sets were similar to the mid-parent value (3354 µg/kg) but ranges were from 1716 to 8753 µg/kg. There was no correlation between leaf peramine and ergovaline (r=0.01). These data suggest that endophytically produced alkaloids are independently regulated and are controlled by both plant and endophyte genotype.