Expression of soybean-embryo lipoxygenase 2 in transgenic tobacco tissue.

To assess the role of lipoxygenase (LOX; EC 1.13.11.12) in plants, we increased the expression of LOX in the tissues of Nicotiana tabacum L. cv. 'KY 14' by over-expression of the LOX2 gene from the soybean (Glycine max (L.) Merrill) embryo. The LOX2 cDNA was manipulated by replacing its 5'-untranslated sequence with the translational enhancer of the alfalfa mosaic virus (AMV), and subcloned into a plant expression vector, 3' to a duplicated cauliflower mosaic virus 35S promoter. The AMV-LOX2 construct was transferred into tobacco using Agrobacterium tumefaciens strain A281. The LOX2 was expressed in transgenic tobacco calli, leaves of transgenic plants, and their seed progeny at levels up to 0.1-0.2% of the total extracted protein. The introduced LOX2 affected fatty-acid oxidative metabolism as evidenced by a 50-529% increase in C6-aldehyde production. The impact on C6-aldehyde formation was greater than the effect on production of fatty-acid hydroperoxides. This is consistent with other studies indicating the greater propensity of soybean embryo LOX2 in generating C6-aldehydes than that of other well-characterized LOX isozymes.