Iturin A was purchased from Sigma (Tokyo, Japan). Iturin A derivative
peptides, NH2-(L-Asn)-(D-Tyr)-(D-Asn)-(L-Gln)-(L-Pro)-(DAsn)-(L-Ser)-COOH
(ATAGPAS), NH2-(L-Asn)-(D-Tyr)-(D-Asn)-(LGln)-COOH
(ATAG), and NH2-(D-Asn)-(L-Gln)-(L-Pro)-(D-Asn)-
COOH (AGPA), were synthesized by Greiner Bio-One (Tokyo, Japan).
The concentrations of iturin A and the derivative peptides were
adjusted to 0.01 mg/ml with 0.02% Tween 20. Each solution or
water was applied to a rosette leaf of 30-day Arabidopsis seedlings
by spraying (1 ml each). The seedlings were incubated at 25 C for
the indicated periods in an incubator (11.8 Wm2
/14 h/d).