Growth stress induces glucosinolate changes in pakchoy (Brassica campestris ssp. chinensis)

Abstract

Glucosinolates (GS) are sulphur-containing compounds that yield breakdown products that contribute to the characteristic flavor and aroma of Cruciferae crops. No studies have been conducted on the influence of the environment on the GS levels in the leafy vegetable pakchoy (Brassica campestris ssp. chinensis). Because of the importance of GS, we studied in two separate experiments, the effect of nitrogen (N) nutrition and turnip mosaic virus (TuMV) infection on the GS content of this vegetable. As part of our study in a separate experiment, we also determined the GS profile of developing plants from 5 to 35 d. Nitrogen was applied at 14, 84, and 224 mg L−1 and plants were manually inoculated with TuMV during early (15 d) and late (30 d) development. Plants were grown hydroponically and harvested 35 or 36 d after seeding. Developing plants accumulated GS in leaf tissues. Nine GS were detected in pakchoy tissues. Plants supplied with 14 mg L−1 N and those infected with TuMV during early development had lower fresh and dry weights and had higher total GS content than control plants. Alterations in the concentrations and relative percentages of several GS were also evident in these plants. A decline in the 1-methoxy-3-indolylmethyl-GS percentage in the mature leaf tissues of stressed plants commonly occurred. Data from these experiments indicated that certain GS changes in pakchoy were tissue and stress specific. Key words:Brassica, glucosinolates, nitrogen, turnip mosaic virus