Poster: Lipids & Related Molecules

Abs # 851: Effect of 16C monounsaturated fatty acids on cis-3-hexenal production

Presenter:	Hong, Mei , mhong@eden.rutgers.edu
Authors	Hong, Mei  (A)   Zilinskas, Barbara A. (A)   Knipple, Douglas C. (B)   Chin, Chee-Kok  (A)
Affiliations:	(A): Department of Plant Biology and Pathology, Rutgers University (B): Department of Entomology, Cornell University

A d11 desaturase gene from cabbage looper moth (Trichoplusia ni) and a d9 desaturase gene from yeast (Saccharomyces cerevisiae) were introduced into tobacco (Nicotiana tabacum) plants. The introduction of these genes in tobacco plants not only caused changes in fatty acid profiles but also led to alterations in certain fatty acid-derived volatile compounds such as cis-3-hexenal, a major leaf volatile derived from linolenic acid (18:3). The increased cis-3-hexenal level in the transgenic plants, however, is not due to the increased production of linolenic acid. There was no increase in this polyunsaturated fatty acid in either total or free fatty acid profiles of transgenic plants. On the other hand, there was a sharp increase in the palmitoleic acid (16:1d9) level in transgenic plants expressing the d9 desaturase, and the presence of a novel 11-hexadecenoic acid (16:1d11) was detected in transformants expressing the d11 desaturase. The transgenic plants were also found to possess elevated levels of 13-lipoxygenase (13-LOX), an enzyme involved in cis-3-hexenal production. In vitro experiments showed palmitoleic acid and 11-hexadecenoic acid do not affect LOX activity. However, wild-type tobacco leaves treated with these two fatty acids had a higher level of cis-3-hexenal. The results suggest that the elevated 16:1Dd/16:111 in transgenic plants probably is the reason for the increased level of cis-3-hexenal. Whether this increase is through the effect of these two 16C monounsaturated fatty acids on 13-LOX in vivo is still being examined.