초록
<P>Native to South America, <I>Alstroemeria</I> flowers are known for their colourful tepals, and <I>Alstroemeria</I> hybrids are an important cut flower. However, in common with many commercial cut flowers, virtually all the commercial <I>Alstroemeria</I> hybrids are not scented. The cultivar ‘Sweet Laura’ is one of very few scented commercial <I>Alstroemeria</I> hybrids. Characterization of the volatile emission profile of these cut flowers revealed three major terpene compounds: (<I>E</I>)-caryophyllene, humulene (also known as α-caryophyllene), an ocimene-like compound, and several minor peaks, one of which was identified as myrcene. The profile is completely different from that of the parental scented species <I>A. caryophyllaea</I>. Volatile emission peaked at anthesis in both scented genotypes, coincident in cv. ‘Sweet Laura’ with the maximal expression of a putative terpene synthase gene <I>AlstroTPS.</I> This gene was preferentially expressed in floral tissues of both cv. ‘Sweet Laura’ and <I>A. caryophyllaea.</I> Characterization of the <I>AlstroTPS</I> gene structure from cv. ‘Sweet Laura’ placed it as a member of the class III terpene synthases, and the predicted 567 amino acid sequence placed it into the subfamily TPS-b. The conserved sequences R<SUP>28</SUP>(R)X<SUB>8</SUB>W and D<SUP>321</SUP>DXXD are the putative Mg<SUP>2+</SUP>-binding sites, and <I>in vitro</I> assay of <I>AlstroTPS</I> expressed in <I>Escherichia coli</I> revealed that the encoded enzyme possesses myrcene synthase activity, consistent with a role for <I>AlstroTPS</I> in scent production in <I>Alstroemeria</I> cv. ‘Sweet Laura’ flowers.</P>