High nitrogen supply and carbohydrate content reduce fungal endophyte and alkaloid concentration in Lolium perenne.
The relationship between cool-season grasses and fungal endophytes is widely regarded as mutualistic, but there is growing uncertainty about whether changes in resource supply and environment benefit both organisms to a similar extent. Here, we infected two perennial ryegrass (Lolium perenne) cultivars (AberDove, Fennema) that differ in carbohydrate content with three strains of Neotyphodium lolii (AR1, AR37, common strain) that differ intrinsically in alkaloid profile. We grew endophyte-free and infected plants under high and low nitrogen (N) supply and used quantitative PCR (qPCR) to estimate endophyte concentrations in harvested leaf tissues. Endophyte concentration was reduced by 40% under high N supply, and by 50% in the higher sugar cultivar. These two effects were additive (together resulting in 75% reduction). Alkaloid production was also reduced under both increased N supply and high sugar cultivar, and for three of the four alkaloids quantified, concentrations were linearly related to endophyte concentration. The results stress the need for wider quantification of fungal endophytes in the grassland-foliar endophyte context, and have implications for how introducing new cultivars, novel endophytes or increasing N inputs affect the role of endophytes in grassland ecosystems.
Rasmussen
Susanne
S
AgResearch, P.B. 11008, Palmerston North, New Zealand.
Parsons
Anthony J
AJ
AgResearch, P.B. 11008, Palmerston North, New Zealand.
Bassett
Shalome
S
AgResearch, P.B. 11008, Palmerston North, New Zealand.
Christensen
Michael J
MJ
AgResearch, P.B. 11008, Palmerston North, New Zealand.
Hume
David E
DE
AgResearch, P.B. 11008, Palmerston North, New Zealand.
Johnson
Linda J
LJ
AgResearch, P.B. 11008, Palmerston North, New Zealand.
Johnson
Richard D
RD
AgResearch, P.B. 11008, Palmerston North, New Zealand.
Simpson
Wayne R
WR
AgResearch, P.B. 11008, Palmerston North, New Zealand.
Stacke
Christina
C
AgResearch, P.B. 11008, Palmerston North, New Zealand.
Voisey
Christine R
CR
AgResearch, P.B. 11008, Palmerston North, New Zealand.
Xue
Hong
H
AgResearch, P.B. 11008, Palmerston North, New Zealand.
Newman
Jonathan A
JA
Department of Environmental Biology, University of Guelph, Ontario, Canada N1G 2W1.
D000470:Alkaloids / Q000378:metabolism*; D002241:Carbohydrates / Q000032:analysis; D005658:Fungi / Q000235:genetics / Q000378:metabolism*; D008129:Lolium / Q000737:chemistry / Q000378:metabolism* / Q000382:microbiology*; D009584:Nitrogen / Q000378:metabolism*; D010940:Plant Proteins / Q000032:analysis; D016133:Polymerase Chain Reaction
D000470:Alkaloids; D002241:Carbohydrates; D010940:Plant Proteins; D009584:Nitrogen