Taiwania (Taiwania cryptomerioidesHayata) 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; designatedTcPLR1,TcPLR2.2andTcPLR3), 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.
Zanthoxylum ailanthoides is a traditional
spice crop in Taiwan with unique smells and tastes that differ between
prickly (young) and nonprickly (mature) leaves. Different volatile
terpenes between prickly young and nonprickly mature leaves were identified
and considered to be one of the sources of their aromas. A transcriptome
database was established to explore the biosynthesis of these compounds,
and candidate terpene synthase genes were identified. The functions
of these synthases were investigated using recombinant protein reactions
in both purification and coexpression assays. ZaTPS1, ZaTPS2, and ZaTPS3 are germacrene D synthases,
with different amino acid sequences. The main products of ZaTPS4 are trans-α-bergamotene and
(E)-β-farnesene, whereas ZaTPS5 forms multiple products, and ZaTPS6 produces
β-caryophyllene. ZaTPS7 forms monoterpene (E)-β-ocimene and sesquiterpene (E,E)-α-farnesene. Reverse transcription PCR
of ZaTPS gene expression in young and mature leaves
revealed that ZaTPS1 was responsible for the mellow
aroma in mature leaves. The expression of ZaTPS6
suggested that it plays a role in the background aromas of both types
of leaves. Our findings deepened the understanding of the volatile
compounds of Z. ailanthoides and revealed
the source of its unique aromas by clarifying the biosynthesis of
these compounds.
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