EFFECTS OF ENVIRONMENT ON THE COMPOSITION OF EPICUTICULAR WAX ESTERS FROM KALE AND SWEDE

The composition of intact leaf epicuticular wax esters of two individu al genotypes each of kale and swede grown indoors (I) and outdoors (O) at SCRI, Scotland, and outdoors at Wadenswil in Switzerland (S), were determined by GC-mass spectrometry. For all genotypes (I, O, S) ester s were found to Consist of unbranched (n-) and branched anteiso- (a-) and iso-(i-) components in the a: a, a:i, i:a, a:n, n: a, n:n and i/n: n/i acid-alcohol combinations. Esterification was non-random, n:n and doubly branched br-lbr-combinations were favoured over mixed n-/br- co mbinations. Combinations with extremes of acid and alcohol chain-lengt h were generally uncommon, although longer-chain alcohols were more pr edominant in some swede esters. There were considerable compositional differences between indoor-grown plants (I) and those grown outdoors ( O and S). In general, i: nln : i, i: a and a: i esters were relatively more abundant in (O and S) and nn and n: a esters were more abundant in (I), whereas a:n and a:a esters were of similar abundance in all O, O and S). Generally, (I)-grown plants were found to have proportional ly more esters of longer chain-length and (O, S)-grown plants proporti onally more esters of shorter chain-length. For kale a: a, n:n; a:n an d n:a esters, this was particularly related to variation in alcohol ch ain-length. There were also major compositional differences between ka le and swede esters, long-acid-short-alcohol combinations were more pr ominent in the former, while short-acid-long-alcohol combinations domi nated in the latter. (C) 1997 Elsevier Science Ltd. All rights reserve d.