Jj. Alarcon et M. Malone, SUBSTANTIAL HYDRAULIC SIGNALS ARE TRIGGERED BY LEAF-BITING INSECTS INTOMATO, Journal of Experimental Botany, 45(276), 1994, pp. 953-957
In various plants, defence responses can be induced throughout the sho
ot by localized damage or insect attack. Activation of such systemic d
efence responses must involve a rapid long-distance signal of wounding
. There is firm evidence that, in the case of localized heat wounds, s
ystemic signalling occurs by hydraulic dispersal of chemical elicitors
. However, more natural wounds (such as those imposed by leaf-biting i
nsects) may trigger only small hydraulic events, and it is not clear w
hether hydraulic dispersal could account for wound signalling in these
cases. It is shown here that partial defoliation offers a method for
amplifying wound-induced hydraulic events in tomato. Using this amplif
ication, it is demonstrated that brief feeding by individual leaf-eati
ng insects triggers substantial hydraulic events. The mass flows assoc
iated with these events are shown to be sufficient to drive hydraulic
dispersal of elicitors through the tomato plant. It is concluded that
hydraulic dispersal could be of major importance for wound signalling
in plants in the natural environment.