E. Gianoli et Hm. Niemeyer, CHARACTERISTICS OF HYDROXAMIC ACID INDUCTION IN WHEAT TRIGGERED BY APHID INFESTATION, Journal of chemical ecology, 23(12), 1997, pp. 2695-2705
Hydroxamic acids (Hx) are natural products of Gramineae that are assoc
iated with cereal resistance to pests. We aimed at characterizing the
induction of Hx accumulation in seedlings of wheat, Triticum aestivum,
by short-term infestation of the cereal aphid, Rhopalosiphum padi. A
load of 25 aphids increased significantly the Hx levels in the infeste
d primary leaf in comparison with control levels. Lower loads did not
increase Hx concentration. Aphid infestation lasting 16 hr did not eli
cit induction of Hx, even after a time-lag of 32 hr to allow the expre
ssion of any induced response. Forty eight hours was the minimum durat
ion of aphid infestation required to trigger Hx induction. The age of
the infested tissue (the primary leaf) did not affect induction. Simil
ar increases of Hx were found in unfolding, expanding, and totally exp
anded primary leaves. It was determined that the regime of nutrient su
pply (N-intensive nutritive solutions at low and high concentration) t
o wheat seedlings had no effect on the magnitude of the aphid-induced
Hx (N-based secondary metabolites). Results obtained are discussed in
the framework of general theories of plant defense allocation.