Volatile composition and classification of Lilium flower aroma types and identification, polymorphisms, and alternative splicing of their monoterpene synthase genes

Abstract

Lily is a well-known ornamental plant with a diversity of fragrant types. Basic information on lily floral scent compounds has been obtained for only a few accessions, and little is known about Lilium aroma types, the terpene synthase genes that may play roles in the production of key volatiles, or the range of monoterpenes that these genes produce. In this study, 41 cultivars were analyzed for volatile emissions, and a total of 46 individual volatile compounds were identified, 16 for the first time in lilies. Lily accessions were classified into six groups according to the composition of major scent components: faint-scented, cool, fruity, musky, fruity-honey, and lily. Monoterpenes were one of the main groups of volatiles identified, and attention was focused on terpene synthase (TPS) genes, which encode enzymes that catalyze the last steps in monoterpene synthesis. Thirty-two candidate monoterpene synthase cDNAs were obtained from 66 lily cultivars, and 64 SNPs were identified. Two InDels were also shown to result from variable splicing, and sequence analysis suggested that different transcripts arose from the same gene. All identified nucleotide substitution sites were highly correlated with the amounts of myrcene emitted, and InDel site 230 was highly correlated with the emission of all major monoterpenoid components, especially (E)-β-ocimene. Heterologous expression of five cDNAs cloned from faint-scented and strong-scented lilies showed that their corresponding enzymes could convert geranyl diphosphate to (E)-β-ocimene, α-pinene, and limonene. The findings from this study provide a major resource for the assessment of lily scent volatiles and will be helpful in breeding of improved volatile components.

A Comparative Analysis of Floral Scent Compounds in Intraspecific Cultivars of Prunus mume with Different Corolla Colours

“…Both the composition and the amount of the volatiles determine the specific flower fragrance [19]. The number of volatiles emitted from P. mume is less than other species, such as bearded iris (219) [10], Lithophragma (132) [20], G. sempervirens (81) [8], but approximate to Lilium [6], P. mume hybrids, and Cymbidium [21]. Comprehensive analysis of the floral scent profiles indicates that the fragrance may be not straightly connected with the number of compositions but their concentration.…”

“…The composition and number of VOCs vary among different species or even in interspecific and intraspecific cultivars [4,5]. In recent years, more and more studies focusing on floral fragrance profiles have been performed in many fragrant plants, including Lilium [6,7], Gelsemium sempervirens [8], Chimonanthus praecox [9], Camellia [4], Polianthes tuberosa [5], and bearded irises [10], etc. VOCs released from these flowers are basically divided into four classes by the biosynthesis origin: terpenoids, phenylpropanoids/benzenoids, fatty acid derivatives, and compounds containing nitrogen/sulfur [11].…”

Floral scent components in Rhododendron fortunei and its regulation by gene expression of S-adenosyl-l-methionine:benzoic acid carboxyl methyl transferase (BAMT)

“…A total of 5 terpenoids derived from the MEP and MVA pathways were also detected in this study. Terpenoids are the secondary abundant metabolites commonly found in plants [6], most of which have a strong sweet, oral and woody aroma. Fatty acid derivatives are the most diverse compounds having 15 species detected including alkanes, alkenes, alcohols, aldehydes and other compounds, derived from the lipoxygenase pathway [7].…”

“…x10 -3 / sample weight (kg). Then the aromatic value was calculated for each components respectively according to the threshold of odor [6].…”

Genes and genome editing tools for breeding desirable phenotypes in ornamentals

“…Terpene synthases (TPSs) are the key enzymes in the biosynthetic pathways of terpenoids (Tholl 2006 , 2015 ). Monoterpenes, which include limonene, (E)-b-ocimene, myrcene, linalool, and alpha- and beta-pinene, are commonly found in floral volatiles of lilium, rose, orchid, snapdragon, petunia, Freesia , Alstroemeria , Clarkia , Iris (Du et al 2019 ). The second major class of plant VOCs are represented by phenylpropanoids and benzenoids and derive from shikimic acid via phenylanaline, cinnamic acid and further decarboxylation and ring oxidation (Dunkel et al 2009 ; Duradeva 2002 ; Knudsen et al 2006 ).…”