EFFECTS OF WOUNDING ON GLUCOSINOLATES IN THE COTYLEDONS OF OILSEED RAPE AND MUSTARD

Mechanical wounding or feeding by the flea beetle, Phyllotreta cruciferae, caused the concentration of indole glucosinolates (3-indolylmethyl and 4-hydroxy-3-indolylmethyl) in the cotyledons of one-week-old seedlings of the oilseed rapes Brassica napus and B. rapa and the mustard B. juncea, to increase as much as three-fold. In B. napus, a single bout of wounding in one cotyledon produced a signal that caused the concentration of 3-indolylmethyl glucosinolate to increase in the unwounded cotyledon, in the first true leaves (seven days after cotyledon wounding) but not in the second true leaves (14 days after cotyledon wounding). Severity of wounding, split versus simultaneous wounding, light intensity and sulphate nutrition also affected wound-induced change in the concentration of this indole glucosinolate. The concentration of aliphatic and aromatic glucosinolates in the mustards, B. juncea (allyl) and Sinapis alba (p-hydroxybenzyl) were unchanged in wounded cotyledons. No correlation was found between wound-induced resistance against the flea beetle Phyllotreta cruciferae and the presence, absence or change in any glucosinolate in the cotyledons of these species.