Changes in fatty acid composition during development of tissues of coconut(Cocos nucifera L.) embryos in the intact nut and in vitro

Intact coconuts were germinated in situ and compared with excised zygotic e mbryos germinated in vitro. The growth of the embryonic tissue and their fa tty acid compositions were measured. Haustoria, plumules and radicles of co conuts germinated in situ grew continuously and proportionately throughout the 120 d experiment with haustauria increasing to 45 g nut(-1) and weighin g 4-5-fold more than the other two tissues. The plumules and radicles of th e seedlings cultured in vitro also grew continuously but the haustoria grew sporadically between 15 d and 75 d in culture and, at 250 mg nut(-1) after 75 d, were smaller than the other two tissues. All the tissues of the nuts grown in situ contained significant amounts of lauric acid, the acid chara cteristic of coconut oil, as well as longer chain saturated and unsaturated fatty acids. The content of medium and long chain fatty acids increased in all growing tissues as the experiment proceeded, especially the haustorium which contained 24-35% of its fatty acid as lauric acid; the fat content o f solid endosperm reduced during this period. Seedlings grown in vitro, on the other hand, failed to accumulate lauric acid in any of their tissues (h austorium contained 6-11% of its fatty acid as lauric acid). The results ma y have implications for the design of growth media for growing zygotic and somatic cultures of coconut and may provide a marker for successful germina tion.