TY - JOUR
T1 - Contribution of fungal loline alkaloids to protection from aphids in a grass-endophyte mutualism
AU - Wilkinson, H. H.
AU - Siegel, M. R.
AU - Blankenship, J. D.
AU - Mallory, A. C.
AU - Bush, L. P.
AU - Schardl, C. L.
PY - 2000
Y1 - 2000
N2 - Fungal endophytes provide grasses with enhanced protection from herbivory, drought, and pathogens. The loline alkaloids (saturated 1-aminopyrrolizidines with an oxygen bridge) are fungal metabolites often present in grasses with fungal endophytes of the genera Epichloe or Neotyphodium. We conducted a Mendelian genetic analysis to test for activity of lolines produced in plants against aphids feeding on those plants. Though most loline-producing endophytes are asexual, we found that a recently described sexual endophyte, Epichloe festucae, had heritable variation for loline alkaloid expression (Lol+) or non-expression (Lol-). By analyzing segregation of these phenotypes and of linked DNA polymorphisms in crosses, we identified a single genetic locus controlling loline alkaloid expression in those E. festucae parents. We then tested segregating Lol+ and Lol- full-sibling fungal progeny for their ability to protect host plants from two aphid species, and observed that alkaloid expression cosegregated with activity against these insects. The in planta loline alkaloid levels correlated with levels of anti-aphid activity. These results suggested a key role of the loline alkaloids in protection of host plants from certain aphids, and represent, to our knowledge, the first Mendelian analysis demonstrating how a fungal factor contributes protection to plant-fungus mutualism.
AB - Fungal endophytes provide grasses with enhanced protection from herbivory, drought, and pathogens. The loline alkaloids (saturated 1-aminopyrrolizidines with an oxygen bridge) are fungal metabolites often present in grasses with fungal endophytes of the genera Epichloe or Neotyphodium. We conducted a Mendelian genetic analysis to test for activity of lolines produced in plants against aphids feeding on those plants. Though most loline-producing endophytes are asexual, we found that a recently described sexual endophyte, Epichloe festucae, had heritable variation for loline alkaloid expression (Lol+) or non-expression (Lol-). By analyzing segregation of these phenotypes and of linked DNA polymorphisms in crosses, we identified a single genetic locus controlling loline alkaloid expression in those E. festucae parents. We then tested segregating Lol+ and Lol- full-sibling fungal progeny for their ability to protect host plants from two aphid species, and observed that alkaloid expression cosegregated with activity against these insects. The in planta loline alkaloid levels correlated with levels of anti-aphid activity. These results suggested a key role of the loline alkaloids in protection of host plants from certain aphids, and represent, to our knowledge, the first Mendelian analysis demonstrating how a fungal factor contributes protection to plant-fungus mutualism.
KW - Amplified fragment length polymorphism (AFLP)
KW - Festuca
KW - Lolium spp.
KW - Rhopalosiphum padi
KW - Schizaphis graminum
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U2 - 10.1094/MPMI.2000.13.10.1027
DO - 10.1094/MPMI.2000.13.10.1027
M3 - Article
C2 - 11043464
AN - SCOPUS:0033807791
SN - 0894-0282
VL - 13
SP - 1027
EP - 1033
JO - Molecular Plant-Microbe Interactions
JF - Molecular Plant-Microbe Interactions
IS - 10
ER -