THE EFFECT OF GROWTH REGULATORS, LIGHT AND TEMPERATURE ON FLAVOUR PRODUCTION IN CELERY TISSUE CULTURES

Abstract

S ummary Cell suspensions of celery ( Apium graveolens L.) were subcultured on media containing a range of auxins and antiauxins to replace 2,4‐dichlorophenoxyacetic acid (2,4‐D). Where the cultures showed a low growth rate and became green, the cells and media contained flavour compounds, the phthalides (3‐butyl phthalide and sedanenolide) and other terpenoid compounds. Maximum secondary product synthesis and greening was in media which contained 3,5‐dichlorophenoxy‐acetic acid (3,5‐D). In order to stimulate flavour synthesis in cultures in a medium containing 2,4‐D, the cultures were exposed to different fight and temperature regimes for varying periods during their growth cycle. Although growth was reduced in darkness and at high (30 °C) and intermediate (20 °C) temperatures, no stimulation of phthalide and terpenoid synthesis occurred. However, when the cultures were maintained at 4 °C for the first 5 d of the growth cycle and then transferred to 25 °C, phthalides and other terpenoids, particularly limonene, were released into the medium. An analysis of aggregated and finely dispersed cells on a 2,4‐D medium showed the aggregates contained phthalides and terpenoids, but these were not present in the dispersed cells. It is suggested that the altered internal cell environment in the green, aggregated or temperature stressed cells contributed to the ability of the cells to synthesize secondary products.