Ontogenetic Changes of 2-Propenyl and 3-Indolylmethyl Glucosinolates in Brassica carinata Leaves as Affected by Water Supply

Concentrations of 2-propenyl and 3-indolylmethyl glucosinolates in two lines of Brassica carinata (Holeta-1 and 37-A) were assessed during the vegetative life cycle under optimal or drought-inducing water supply conditions. In the well-watered treatment, 2-propenyl and 3-indolylmethyl glucosinolate concentrations remained almost constant from the 6-8 to the 15-16 leaf stage, whereas a drought-induced water supply led to a distinct increase of these glucosinolates. Generally, the 2-propenyl concentration was higher in Holeta-1 at each leaf stage under drought stress as compared with 37-A, indicating a B. carinata line-specific drought response. The drought-induced glucosinolate accumulation seems to be integrated in the plant's process of osmotic adjustment. It seems that under drought, there is a shift from primary to secondary metabolism, thereby promoting glucosinolate synthesis. Thus, by keeping the relative soil-water content below 80%, glucosinolate concentrations could be increased up to the 15-16 leaf stage, resulting in better plant nutritional quality of B. carinata.