However,ryegrass endophyte contributes to livestock productivity,by ensuring a sustained leafy ryegrass pasture in stressful situations.The alternative to endophyte- sp or tropical grassesyasureom poor et al 1996). ophyte-infected es The discovery of the novel AR1 endophyte could completely change this scenario as outlined later (Easton et al..2001). 2.4 Alkaloid Metabolites Produced by Endophyte Before 1980.it was thought likely that a fungus was involved with ryegrass staggers,and research aimed to isolate the chemical compound(s)responsible. The discovery of the role of the endophyte hastened this process,and lolitrem B was isolated and described (Gallagher et al., 981). Several related compounds have been id entified,but lolitrem B is mo dant and perhaps the mo ost poten (Mile em ay Smith 999.1994. et a 1993)a staggers na n the ue to enceoe ins er he ueot0npamnas different.and peramine was isolated and described (Rowan Gay or 1986) arch had identified ergovaline as the primany fescue toxin.and this compound was later found in endophyte-infected PRG(Rowan Shaw 1987).Ergovaline and lolitrem B primarily studied for their effects on livestock,also offer protection against invertebrate pests (Dymock et al.,1989;Ball et al.,1997).Co-evolution of endophyte and host is reflected in the array of compounds occurring in different endophyte-infected grasses (Lane et al.,2000). Endophyte produces a range of alkaloid metabolites (Lane et al.,1999;Lane,1999) Endophyte was sho Bwas shown to be thegent or ryegrafastaggers (hetchen Harvey, 1981 e major ecte caus tor (Gall et a 1981).althc n yegras: re tre D i 9 nd su al 1989: adult Asw Peramine was shown to be the major causal factor(Rowan Ga or 1986).Tall fescue toxicosis is associated with endophyte infection (Hoveland et al.,1980).an d the chief toxin responsible is ergovaline (Yates et al.,1985).This compound is also found in infected ryegrass(Rowan et al.,1990),accounting for reports of heat stress of livestock in northern NZ (Easton et a/.,1996;Sutherland,1984)and perhaps interacting with lolitrem B to exacerbate ryegrass staggers(Fletcher Easton,1997).Ergovaline is the most abundant of a number of lysergyl compounds produced by endophyte,and these may have a range of pharmacological effects.They have been shown to contribute to ryegrass resistance against black eetle (Ball et al.,1997c).Other less-understood compounds are also produced by endophytes in their host grasses (Lane ef al.,2000). 1995: Keogh 1996) ergovaline PAGE 7 However, ryegrass endophyte contributes to livestock productivity, by ensuring a sustained leafy ryegrass pasture in stressful situations. The alternative to endophyte￾infected ryegrass in many situations would be bare ground, or pasture dominated by Poa spp or tropical grasses of poor quality (Campbell et al., 1996). Endophyte-infected ryegrass pastures generally provide more digestible dry matter to grazing livestock than endophyte-free pastures. The discovery of the novel AR1 endophyte could completely change this scenario as outlined later (Easton et al., 2001). 2.4 Alkaloid Metabolites Produced by Endophyte Before 1980, it was thought likely that a fungus was involved with ryegrass staggers, and research aimed to isolate the chemical compound(s) responsible. The discovery of the role of the endophyte hastened this process, and lolitrem B was isolated and described (Gallagher et al., 1981). Several related compounds have been identified, but lolitrem B is the most abundant and perhaps the most potent (Miles et al., 1994). Paxilline is similar to lolitrem B and is a tremorgen itself (McLeay & Smith, 1999; Fletcher et al., 1993), but much milder (Easton pers. comm.). Mild staggers has occurred in the absence of lolitrem B (Fletcher et al., 1993) and this may have been due to paxilline or other unidentified neurotoxins. The main compound responsible for protection from ASW was shown to be different, and peramine was isolated and described (Rowan & Gaynor, 1986). USA research had identified ergovaline as the primary fescue toxin, and this compound was later found in endophyte-infected PRG (Rowan & Shaw 1987). Ergovaline and lolitrem B, primarily studied for their effects on livestock, also offer protection against invertebrate pests (Dymock et al., 1989; Ball et al., 1997). Co-evolution of endophyte and host is reflected in the array of compounds occurring in different endophyte-infected grasses (Lane et al., 2000). Endophyte produces a range of alkaloid metabolites (Lane et al., 1999; Lane, 1999). Endophyte was shown to be the agent of ryegrass staggers (Fletcher & Harvey, 1981), and lolitrem B was shown to be the major causal factor (Gallagher et al., 1981), although infected ryegrass may contain a number of similar compounds (Miles et al., 1992), some more tremorgenic than others. Lolitrem B is also active against ASW, deterring larval feeding and reducing larval growth rates and survival (Dymock et al., 1989a; Prestidge & Gallagher, 1988). As mentioned above, endophyte deters feeding by adult ASW. Peramine was shown to be the major causal factor (Rowan & Gaynor, 1986). Tall fescue toxicosis is associated with endophyte infection (Hoveland et al., 1980), and the chief toxin responsible is ergovaline (Yates et al., 1985). This compound is also found in infected ryegrass (Rowan et al., 1990), accounting for reports of heat stress of livestock in northern NZ (Easton et al., 1996; Sutherland, 1984) and perhaps interacting with lolitrem B to exacerbate ryegrass staggers (Fletcher & Easton, 1997). Ergovaline is the most abundant of a number of lysergyl compounds produced by endophyte, and these may have a range of pharmacological effects. They have been shown to contribute to ryegrass resistance against black beetle (Ball et al., 1997c). Other less-understood compounds are also produced by endophytes in their host grasses (Lane et al., 2000). The location of the alkaloid metabolites in the plant reflects in part the location of the endophyte (Ball et al., 1995; Keogh et al., 1996); lolitrem B and ergovaline are found PAGE 7