Abstract

VILLA-RUANO, Nemesio; BETANCOURT-JIMENEZ, Martha G.  and  LOZOYA-GLORIA, Edmundo. cDNA isolation and gene expression of kaurene oxidase from Montanoa tormentosa (Zoapatle). Rev. latinoam. quím [online]. 2010, vol.38, n.2, pp.81-88. ISSN 0370-5943.

The ent-kaurenoic acid (KA) is the precursor of gibberellins in all plants. In a previous report, we proposed the biosynthetic conversion of KA into grandiflorenic acid (GF) in "zoapatle" (Montanoa tomentosa), which is the most important bioactive diterpene of this Mexican medicinal plant. It is known that KA is the product of ent-kaurene oxidase enzyme (KO), being so a key enzyme for all plants. This time, we show the isolation of a full-length ent-kaurene oxidase cDNA from Montanoa tomentosa (MtKO-cDNA). Expression analyses of MtKO-cDNA were compared with endogenous levels of KA in leaves of different ages. Obtained data shown that KA is mainly synthesized in the mesophyll of young leaves and accumulated later on in old leaves including glandular trichomes. However, MtKO gene expression was clear in young leaves but low or null in old tissues and trichomes. The detection of low levels of MtKO transcript in glandular trichomes suggests that these structures may have some role in KA biosynthesis. The high concentration of KA in the whole leaf suggests a possible defense mechanism based on the production and accumulation of such diterpene. The present investigation is a contribution to the characterization of the metabolic pathway of M. tomentosa pharmacological diterpenes.

Keywords : ent-kaurene oxidase; ent-kaurenoic acid; glandular trichomes; grandiflorenic acid; Montanoa tomentosa.