The green odor of plants is characterized by green leaf volatiles (GLVs) composed of C6 compounds. GLVs are biosynthesized from polyunsaturated fatty acids in thylakoid membranes by a series of enzymes. A representative member of GLVs (E)-2-hexenal, known as the leaf aldehyde, has been assumed to be produced by isomerization from (Z)-3-hexenal in the biosynthesis pathway; however, the enzyme has not yet been identified. In this study, we purified the (Z)-3:(E)-2-hexenal isomerase (HI) from paprika fruits and showed that various plant species have homologous HIs.
