Signals and Signalling Pathways in PlantWound Responses - Communication in Plants: Neuronal Aspects of Plant Life - page 396

Table 26.1. Summary of significant results. (Reproduced from Rhodes et al. 1999, with the
permission of Oxford University Press, copyright of the Annals of Botany Company)

Wound type Electrical

event
recorded
with
surface
electrodes

Xylem
reversal

Systemic
proteinase
inhibitor -
no steaming
of petiole
of wounded
leaf or
cotyledon

Systemic
proteinase
inhibitor -
after steaming
of petiole
of wounded
leaf 1 - wound-
types 3-5

Razor cut through cotyledon
in air (1)

- - -

Razor cut through cotyledon,
under water (2)

-

+ +

Small mechanical wound
to terminal leaflet of leaf 1 (3)

- - -

+

Large mechanical wound
to terminal leaflet of leaf 1 (4)

+ + + +

Heat wound
to terminal leaflet of leaf 1 (5)

+ + + +

activity in all parts of the plant; the pattern of PI activity was less obvious
than for wound-type 2, although where differences were found they always
followed the pattern described before. Steam girdling the petiole of leaf 1
did not prevent the systemic induction of PI activity by a severe wound
(wound-types 4 and 5) to the terminal leaflet of that leaf (Table 26.1); sim-
ilar results were obtained by Malone and co-workers using heat-girdling.
Following severe wounds, the patterns of PI activity, electrical activity, and
the distribution of LY are consistent with the distribution of elicitors of PI
synthesis and of electrical activity by hydraulic dispersal in the xylem; for
such wounds, some involvement of the phloem is also possible (Rhodes et
al. 1999).
Following a small mechanical wound (wound-type 3), in most cases, no
LY flowed out of a cotyledon. LY was seen to flow out of leaf 1 following
a large mechanical wound to its terminal leaflet, but not following a small
mechanical wound to the same structure. Small mechanical wounds re-
sulted in much lower levels of PI activity and a different pattern of distri-
bution than those recorded for severe wounds or a razor cut under water:
significant PI activity was found in the wounded terminal leaflet of leaf 1,
and in leaf 3 and in the apex - organs which were identified, using car-
boxyfluorescein, as being active importers via the phloem, but very little
PI activity was found in either of the cotyledons or leaf 2, which corre-