Lathyrus odoratus (sweet pea).

Lathyrus odoratus is a fast-growing, annual herb native only to southwest Italy and Sicily, but widely introduced as an ornamental. The ability of this species to tolerate a wide range of habitats, including disturbed areas, roadsides, secondary forests, as well as natural forests, means that it has the potential to spread much further than it has to date. This species has a climbing or sprawling habit, and consequently, has the capability to displace native species. Currently it is considered invasive in New Zealand and 'possibly invasive' in the Dominican Republic. However, in its native range it is listed as Near Threatened, as it is subject to wild collection threat due to its commercial value.

Functional Characterization of Terpene Synthases Accounting for the Volatilized-Terpene Heterogeneity in Lathyrus odoratus Cultivar Flowers

Lathyrus odoratus (sweet pea) is an ornamental plant with exceptional floral scent, previously used as an experimental organism in the early development of Mendelian genetics. However, its terpene synthases (TPSs), which act as metabolic gatekeepers in the biosynthesis of volatile terpenoids, remain to be characterized. Auto-Headspace Solid-phase Microextraction/Gas chromatography–mass spectrometry analysis of floral volatile terpene constituents from seven sweet pea cultivars identified α-bergamotene, linalool, (−)-α-cubebene, geraniol, β-caryophyllene and β-sesquiphellandrene as the dominant compounds. RNA sequencing was performed to profile the transcriptome of L. odoratus flowers. Bioinformatic analysis identified eight TPS genes (acronymed as LoTPS) that were successfully cloned, heterologously expressed and functionally analyzed. LoTPS4 and LoTPS7, belonging to the TPS-b clade, biochemically catalyzed the formation of monoterpenes and sesquiterpenes. LoTPS3 and LoTPS8, placed in the TPS-a clade, also generated monoterpenes and sesquiterpenes, while LoTPS12 belonging to the TPS-g clade showed linalool/nerolidol synthase activity. Notably, biochemical assays of the recombinant LoTPS proteins revealed their catalytic promiscuity, and the enzymatic products were basically consistent with major volatile compounds released from sweet pea flowers. The data from our study lay the foundation for the chemical ecology, molecular genetics and biotechnological improvement of sweet pea and other legumes (Fabaceae).

The molecular basis for an ancient colour mutant in sweet pea (Lathyrus odoratus)

The classic A1 locus in sweet pea (Lathyrus odoratus) was investigated by Bateson, Punnett, and Saunders in the early 20th century history of Mendelian genetics. The mutation, in the form of the pink and white cultivar ‘Painted Lady’, is known from the 18th century. We show that this locus is associated with a single base pair mutation (332 G/A) in the flavonoid 3′,5′-hydroxylase (F3′5′H) gene. This results in an amino acid change (111 glycine/aspartic acid) in the conserved substrate recognition site 1 of the enzyme. The mutant flower lacks the blue pigment delphinidin and is thus pink and white, rather than purple and blue as in the wild-type. This single amino acid change at a functionally important site appears to convert the enzyme from primary F3′5′H activity to a relatively efficient F3′H, as suggested by heterologous transformation into Arabidopsis PAP1D (a mutant line that produces anthocyanin constitutively).