Dynamics of Neotyphodium uncinatum and N-formylloline in Italian ryegrass, and their relation to insect resistance in the field.
OBJECTIVE
A fungal endophyte, Neotyphodium uncinatum, accumulates N-formylloline, which is toxic to Hemipteran insects, in Italian ryegrass. This study aimed to clarify the dynamics of N. uncinatum and N-formylloline in Italian ryegrass, and their relationship to insect resistance.


RESULTS
Changes in the density and localization of N. uncinatum and N-formylloline in N. uncinatum-infected Italian ryegrass were examined by real-time PCR and gas chromatography, respectively. Neotyphodium uncinatum multiplied on pseudostems at the flowering stage, and then increased on inflorescences at the ripening stage. On the other hand, N-formylloline accumulated heavily in inflorescences and leaf blades, but lightly in pseudostems at the ripening stage. In field experiments, N. uncinatum-infected Italian ryegrass suppressed the occurrence of Stenotus rubrovittatus, which fed on the inflorescences, but was not effective to Laodelphax striatellus, which do not necessarily prefer a particular plant tissue.


CONCLUSIONS
Localization of N. uncinatum and N-formylloline were discordant in Italian ryegrass. The N. uncinatum-infected Italian ryegrass was effective to only insects that prefer to feed on particular plant tissues containing N-formylloline.


CONCLUSIONS
Our data implies that the relationship between insect habits and the dynamics of alkaloids in plants is important for the effective use of endophyte-infected crops.
Agro-Environment Research Division, NARO Kyushu Okinawa Agricultural Research Center, Koshi, Kumamoto, Japan.
K
K
Matsukura
Plant Protection Division, NARO Agricultural Research Center, Tsukuba, Ibaraki, Japan.
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T
Shiba
Forage Grass Laboratory, Forage Crop Research Institute, Japan Grassland Agriculture & Forage Seed Association, Nasushiobara, Tochigi, Japan.
T
T
Sasaki
Agro-Environment Research Division, NARO Kyushu Okinawa Agricultural Research Center, Koshi, Kumamoto, Japan.
K
K
Yoshida
Agro-Environment Research Division, NARO Kyushu Okinawa Agricultural Research Center, Koshi, Kumamoto, Japan.
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M
Matsumura
D000470:Alkaloids / Q000378:metabolism*; D000818:Animals; D018556:Crops, Agricultural; D060026:Endophytes / Q000254:growth & development*; D035264:Flowers / Q000382:microbiology; D006430:Hemiptera / Q000254:growth & development; D008129:Lolium / Q000382:microbiology*; D055328:Neotyphodium / Q000378:metabolism*; D018515:Plant Leaves / Q000382:microbiology; D060888:Real-Time Polymerase Chain Reaction; D012621:Seasons
D000470:Alkaloids; C059478:loline
Laodelphax striatellus; N-formylloline; Stenotus rubrovittatus; crop protection; forage grass