Effect of overexpression of fatty acid 9-hydroperoxide lyase in tomatoes (Lycopersicon esculentum Mill.).
To modify the flavor properties of tomato fruits, cucumber fatty acid hydroperoxide lyase (HPL), which can act on 9-hydroperoxides of fatty acids to form volatile C9-aldehydes, was introduced to tomato plants. Through enzyme assay, high activity of the introduced HPL could be found in either the leaves or fruits of transgenic tomatoes; however, the composition of volatile short-chain aldehydes and alcohols in the transgenic tomato fruits was little modified. This was unexpected because tomato fruits have high lipoxygenase activity to form 9-hydroperoxides. When linoleic acid was added to a crude homogenate prepared from the transgenic tomato fruits, a high amount of C9-aldehyde was formed, but the amount of C6-aldehyde was almost equivalent to that in nontransgenic tomatoes. Through quantification of fatty acid hydroperoxides, it has been revealed that 13-hydroperoxides of fatty acids are preferably formed from endogenous substrate, whereas 9-hydroperoxides are formed from fatty acids added exogenously. From these observations, possible mechanisms to regulate metabolic flow of the lyase pathway are discussed.
Matsui
K
K
Department of Biological Chemistry, Faculty of Agriculture, Yamaguchi University, Yamaguchi 753-8515, Japan. matsui@agr.yamaguchi-u.ac.jp
Fukutomi
S
S
Wilkinson
J
J
Hiatt
B
B
Knauf
V
V
Kajwara
T
T
D000447:Aldehydes / Q000378:metabolism; D006836:Hydro-Lyases / Q000235:genetics* / Q000378:metabolism; D018551:Solanum lycopersicum / Q000201:enzymology / Q000235:genetics*; D019076:Transgenes
D000447:Aldehydes; C443399:9-hydroperoxide lyase; D006836:Hydro-Lyases