Search

Lignans are major bioactive secondary metabolites, which are also formed in the heartwood (hW) of Taiwania (Taiwania cryptomerioides). Their biosynthesis pathways are complex and involve many enzymes and intermediates. To evaluate the extent of the genetic components leading to the variety of lignans in Taiwania hW, 35 Taiwania genotypes of four provenances were surveyed using the proton nuclear magnetic resonance (1H-NMR) and liquid chromatography-mass spectrometry (LC-MS) analyses. The metabolite profiles were statistically evaluated by principal component analysis (PCA) and the general linear model (GLM). The broad-sense heritability (H2) was further evaluated by linear mixed model (LMM) analysis. It was demonstrated that the genetic factor is the major contributor to the abundance of lignans, though the environmental factor also has some effect on it. Among the metabolites detected by 1H-NMR, lignans were the major compounds that exhibited high a H2 (0.52–0.82), which was further verified by LC-MS. The conclusion is that 1H-NMR spectroscopy is suitable for quick screenings, predictions and semi-quantitation of lignans. The high H2 is also indicative of the lignan abundances as traits that can be genetically modified to achieve a significant wood quality improvement. [ABSTRACT FROM AUTHOR]

Taiwania (Taiwania cryptomerioides Hayata) is an indigenous conifer species of Taiwan. Various secondary metabolites of Taiwania with diverse bioactivities have been identified, and lignans are especially abundant in the heartwood (hW). In the present study, the wood of this species was separated to cambium (Cam), sapwood (sW), transition zone (TZ) and hW and their transcriptomes were sequenced. Three pinoresinol-lariciresinol reductases (PLRs; designated TcPLR1, TcPLR2.2 and TcPLR3), which are responsible for lignan biosynthesis, were cloned and their expressions in wood tissues were detected. TcPLRs had higher expression levels in Cam and sW in RNA-seq and reverse transcriptase-polymerase chain reaction (RT-PCR) results. Liquid chromatography-mass spectrometry (LC-MS) analysis of the reaction products of TcPLRs revealed that TcPLR1 can reduce (+)-pinoresinol to lariciresinol, and both TcPLR2.2 and TcPLR3 could reduce (+)-pinoresinol to lariciresinol and secoisolariciresinol. [ABSTRACT FROM AUTHOR]

Taiwania (Taiwania cryptomerioides Hayata) is one of the economically important tree species indigenous to Taiwan. Hundreds of secondary metabolites have been identified from its wood, bark, root, and needles with lignans as the dominant ones. This substance group contributes a lot to the color, durability, and bioactivities of Taiwaniana. The present paper is dedicated to the quantification of radial and longitudinal lignan distribution. The extractives begin to accumulate largely in the transition zone (TZ), and reach a maximum after finishing the heartwood (hW) formation. Both dibenzyl-γ-butyrolactone type and arylnaphthalide type lignans were found in sapwood (sW) except for the compound taiwanin A. Clearly, the heartwood formation of Taiwania differs from the hitherto known hW formation types and it is suggested to be denominated as Taiwania-type hW formation, where the biosynthesis of extractives begins in the sW and where their accumulation is clearly elevated in the TZ. A generalized biosynthesis scheme of Taiwanin is presented showing the putative relationships among the most important dimeric lignans that lead to the formation of taiwanin type lignans. [ABSTRACT FROM AUTHOR]

Taiwania (Taiwania cryptomerioides Hayata) is a conifer species native to Taiwan, which is known for several bioactive secondary metabolites extracted from it. In this study, a sesquiterpene synthase (TPS) gene isolated from Taiwania was in focus. First, a pair of degenerate primers was designed for reverse transcription-polymerase chain reaction based on the total RNA extracted from the leaves of a mature tree. A DNA fragment with the conserved region of TPS gene was obtained. After 5'- and 3'-end amplification, the full-length gene was obtained, which contains an open reading frame of 1791 bp and encodes a predicted molecular mass of 70.2-kDa protein. The gene was highly expressed in young leaves, female flowers, and cones. The expression in leaves was enhanced by salicylic acid. To identify the function of TPS, the recombinant protein from Escherichia coli (Migula) Castellani & Chalmers was incubated with farnesyl diphosphate. Gas chromatography/mass spectrometry analysis and retention time as well as mass spectrum matching with authentic standards revealed that the major product of TPS is sesquiterpene a-gurjunene. The gene was, therefore, designated as Tc-Gur. [ABSTRACT FROM AUTHOR]