DISTRIBUTION AND ACCUMULATION OF THE ALKALOID PERAMINE IN NEOTYPHODIUM LOLII-INFECTED PERENNIAL RYEGRASS

Through the production of alkaloids and mycotoxins, the endophytic fun gus of perennial ryegrass, Neotyphodium lolii, confers resistance to t he host grass against several insect pasture pests and causes health p roblems in livestock. The effects of plant component, plant reproducti ve development, and plant management (trimming) on the concentration a nd accumulation of peramine, the alkaloid thought to be most important for conferring resistance against Argentine stem weevil, were investi gated. Clones of eight different naturally occurring perennial ryegras s-N. lolii associations were used in the experiment, which was conduct ed during spring-summer, which corresponded with the height of plant r eproductive activity. Clones were either trimmed regularly to maintain them in a vegetative state (V clones) or not trimmed, allowing them t o become fully reproductive (R clones). V and R clones of each grass/e ndophyte association were destructively harvested at times that corres ponded roughly with the start, middle, and end of the plant reproducti ve phase. Harvested material was dissected into a number of plant comp onents that were analyzed for peramine concentration by HPLC. All clip pings from the V clones were also analyzed. Peramine concentrations we re usually similar in leaf sheaths and leaf blades, but they decreased as leaf age increased. The seed from R clones and younger sheaths and blades of leaves from vegetative tillers contained the highest concen trations, while the root, crown, and dead leaf tissue contained the lo west. During the inflorescence phase, tissues from reproductive tiller s generally contained lower concentrations than corresponding tissues from vegetative tillers. Also at this time, mean peramine concentratio ns were higher in V clones than in R clones. By the end of the plant r eproductive phase, at the mature seed stage, mean peramine concentrati ons in R and V clones were similar. The seed component, which containe d approximately 75% of the total peramine present in the plant (at a m ean concentration of 63.7 mu g/g), probably accounted for much of the recovery in the R clones.