Volatile emissions of scented Alstroemeria genotypes are dominated by terpenes, and a myrcene synthase gene is highly expressed in scented Alstroemeria flowers.

Native to South America, Alstroemeria flowers are known for their colourful tepals, and Alstroemeria hybrids are an important cut flower. However, in common with many commercial cut flowers, virtually all the commercial Alstroemeria hybrids are not scented. The cultivar 'Sweet Laura' is one of very few scented commercial Alstroemeria hybrids. Characterization of the volatile emission profile of these cut flowers revealed three major terpene compounds: (E)-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 A. caryophyllaea. Volatile emission peaked at anthesis in both scented genotypes, coincident in cv. 'Sweet Laura' with the maximal expression of a putative terpene synthase gene AlstroTPS. This gene was preferentially expressed in floral tissues of both cv. 'Sweet Laura' and A. caryophyllaea. Characterization of the AlstroTPS 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(28)(R)X(8)W and D(321)DXXD are the putative Mg(2+)-binding sites, and in vitro assay of AlstroTPS expressed in Escherichia coli revealed that the encoded enzyme possesses myrcene synthase activity, consistent with a role for AlstroTPS in scent production in Alstroemeria cv. 'Sweet Laura' flowers.

Understanding Alstroemeria pallida Flower Colour: Links between Phenotype, Anthocyanins and Gene Expression.

Flower colour is mainly due to the accumulation of flavonoids, carotenoids and betalains in the petals. Of these pigments, flavonoids are responsible for a wide variety of colours ranging from pale yellow (flavones, flavonols and flavanodiols) to blue-violet (anthocyanins). This character plays a crucial ecological role by attracting and guiding pollinators. Moreover, in the ornamental plants market, colour has been consistently identified as the main feature chosen by consumers when buying flowers. Considering the importance of this character, the aim of this study was to evaluate flower colour in the native Chilean geophyte Alstroemeria pallida, by using three different approaches. Firstly, the phenotype was assessed using both a colour chart and a colourimeter, obtaining CIELab parameters. Secondly, the anthocyanin content of the pigmented tepals was evaluated by high-performance liquid chromatography (HPLC), and finally, the expression of two key flavonoid genes, chalcone synthase (CHS) and anthocyanidin synthase (ANS) was analysed using real-time polymerase chain reaction (PCR). Visual evaluation of A. pallida flower colour identified 5 accessions, ranging from white (Royal Horticultural Society (RHS) N999D) to pink (RHS 68C). Moreover, this visual evaluation of the accessions correlated highly with the CIELab parameters obtained by colourimetry. An anthocyanidin corresponding to a putative 6-hydroxycyanidin was identified, which was least abundant in the white accession (RHS N999D). Although CHS was not expressed differentially between the accessions, the expression of ANS was significantly higher in the accession with pink flowers (RHS 68C). These results suggest a correlation between phenotype, anthocyanin content and ANS expression for determining flower colour of A. pallida, which could be of interest for further studies, especially those related to the breeding of this species with ornamental value.