Organization of monoterpene biosynthesis in Mentha. Immunocytochemical localizations of geranyl diphosphate synthase, limonene-6-hydroxylase, isopiperitenol dehydrogenase, and pulegone reductase.
We present immunocytochemical localizations of four enzymes involved in p-menthane monoterpene biosynthesis in mint: the large and small subunits of peppermint (Mentha x piperita) geranyl diphosphate synthase, spearmint (Mentha spicata) (-)-(4S)-limonene-6-hydroxylase, peppermint (-)-trans-isopiperitenol dehydrogenase, and peppermint (+)-pulegone reductase. All were localized to the secretory cells of peltate glandular trichomes with abundant labeling corresponding to the secretory phase of gland development. Immunogold labeling of geranyl diphosphate synthase occurred within secretory cell leucoplasts, (-)-4S-limonene-6-hydroxylase labeling was associated with gland cell endoplasmic reticulum, (-)-trans-isopiperitenol dehydrogenase labeling was restricted to secretory cell mitochondria, while (+)-pulegone reductase labeling occurred only in secretory cell cytoplasm. We discuss this pathway compartmentalization in relation to possible mechanisms for the intracellular movement of monoterpene metabolites, and for monoterpene secretion into the extracellular essential oil storage cavity.
Turner
Glenn W
GW
Institute of Biological Chemistry, Washington State University, Pullman, Washington 99164, USA.
Croteau
Rodney
R
D000429:Alcohol Oxidoreductases / Q000032:analysis; D019883:Alkyl and Aryl Transferases / Q000032:analysis*; D003577:Cytochrome P-450 Enzyme System / Q000032:analysis; D051231:Farnesyltranstransferase; D018506:Gene Expression Regulation, Plant; D007150:Immunohistochemistry; D027541:Mentha / Q000201:enzymology* / Q000378:metabolism* / Q000648:ultrastructure; D006899:Mixed Function Oxygenases / Q000032:analysis; D039821:Monoterpenes / Q000378:metabolism*; D064430:NAD (+) and NADP (+) Dependent Alcohol Oxidoreductases; D010088:Oxidoreductases / Q000032:analysis*; D010940:Plant Proteins; D013347:Subcellular Fractions / Q000201:enzymology
D039821:Monoterpenes; D010940:Plant Proteins; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; D010088:Oxidoreductases; D000429:Alcohol Oxidoreductases; D064430:NAD (+) and NADP (+) Dependent Alcohol Oxidoreductases; C044952:isopiperitenol dehydrogenase; C120916:limonene-6-hydroxylase; C480901:pulegone reductase; D019883:Alkyl and Aryl Transferases; D051231:Farnesyltranstransferase