EFFECT OF GROWTH TEMPERATURE ON ERUCIC-ACID LEVELS IN SEEDS AND MICROSPORE-DERIVED EMBRYOS OF OILSEED RAPE, BRASSICA-NAPUS L

Effect of growth temperature on the fatty acid composition of triglyce rides was compared for developing seeds and microspore-derived embryos of rapeseed. Plants were grown under standard conditions and subseque ntly seed development was allowed to take place at 15 or 25 degrees C. The composition of seed oil of the low erucic acid cultivar Aurora an d a high erucic acid Guile-derived line were not affected by growth te mperature. The cultivar Reston showed a 30% reduction in erucic acid l evel in seeds from plants grown at 25 degrees C as compared with seeds from plants grown at 15 degrees C. Seeds from plants that were transf erred once during development from 15 degrees to 25 degrees or vice ve rsa, after two thirds of their development had been completed, showed an oil composition similar to seeds that developed completely at the i nitial temperature. Seeds transferred before or during the period of m aximum lipid synthesis showed oil compositions that were similar to oi l formed at the final temperature or intermediate between those of see ds completely grown at 15 degrees C or 25 degrees C, respectively. In microspore-derived embryos (MDEs) similar responses to temperature in the level of erucic acid could be observed. However, absolute levels o f erucic acid in MDEs of both Reston and Guile were 30-50% lower than in seed oil. Results are discussed in relation to possible regulatory mechanisms of temperature-induced changes in oil composition.