cycloartenol/nicotiana

The plant sterol pathway exhibits a major biosynthetic difference as compared with that of metazoans. The committed sterol precursor is the pentacyclic cycloartenol (9β,19-cyclolanost-24-en-3β-ol) and not lanosterol (lanosta-8,24-dien-3β-ol), as it was shown in the late sixties. However, plant

Here we have examined the composition of free sterols and steryl esters of pollen from selected angiosperm species, as a first step towards a comprehensive analysis of sterol biogenesis in the male gametophyte. We detected four major sterol structural groups: cycloartenol derivatives bearing a

Two methyl transfers are involved in the course of plant sterol biosynthesis and responsible for the formation of 24-alkyl sterols (mainly 24-ethyl sterols) which play major roles in plant growth and development. The first methyl transfer applies to cycloartenol, the second one to 24-methylene

In plants, the conversion of cycloartenol into functional phytosterols requires the removal of the two methyl groups at C-4 by an enzymic complex including a sterol 4alpha-methyl oxidase (SMO). We report the cloning of candidate genes for SMOs in Arabidopsis thaliana, belonging to two distinct

Higher plant cells contain a mixture of 24-desmethyl, 24-methyl(ene), and 24-ethyl(idene) sterols in given proportions according to species but also to cell type. As a first step to investigate the function of such sterol compositions in the physiology of a plant, we have illustrated in the present

A genomic fragment encoding one (HMGR1) of the three 3-hydroxy-3-methylglutaryl coenzyme A reductases (HMGRs) from Hevea brasiliensis (H.B.K.) Mull. Arg. (M.-L. Chye, C.-T. Tan, N.-H. Chua [1992] Plant Mol Biol 19: 473-484) was introduced into Nicotiana tabacum L. cv xanthi via Agrobacterium

The first committed step in the conversion of cycloartenol into Delta(5) C24-alkyl sterols in plants is catalyzed by an S-adenosyl-methionine-dependent sterol-C24-methyltransferase type 1 (SMT1). We report the consequences of overexpressing SMT1 in tobacco (Nicotiana tabacum), under control of

Pentacyclic triterpenes (PCTs) represent a major class of bioactive metabolites in banaba (Lagerstroemia speciosa) leaves; however, biosynthetic enzymes and their involvement in temporal accumulation of PCTs are still not studied. We employed an integrated approach involving transcriptomics,

Secondary metabolites in plants play important roles in defence against biotic and abiotic stresses. Although the biosynthesis pathways of secondary metabolites have been extensively studied, the regulatory mechanism of gene expression involved in these pathways remains poorly understood. In this

Two methyl transfers are involved in the biosynthesis of 24-methyl and 24-ethyl sterols, which play major roles in plant growth and development. The first methyl transfer applies to cycloartenol, the second to 24-methylene lophenol. About ten cDNA clones encoding S-adenosyl-L-methionine (AdoMet)

The activities of 3-hydroxy-3-methylglutaryl-coenzyme A reductase, sterol methyl transferase 1 and sterol acyltransferase, key enzymes involved in phytosterol biosynthesis were shown to be co-ordinately regulated during oilseed rape ( Brassica napus L.) and tobacco ( Nicotiana tabacum L.) seed