Search

Abstract Flower color and scent, crucial qualitative characteristics of ornamental plants, display extensive variation. These distinct pigments and scents play a key role in attracting specific pollinators. While previous research primarily delved into the synthetic regulatory mechanisms of individual traits and their respective attraction to insects, recent studies unveil an interconnectedness between flower color and scent through transcriptional regulatory networks. Moreover, evidence suggests that both color and scent actively contribute to insect attraction. This review summarizes the co-regulation and synthesis of pigments and scents, highlighting their pivotal roles in pollinator attraction. The insights provided will serve as valuable references for applications in metabolic engineering, novel variety breeding, and insect and pest detection and management.

Homeologue expression bias occurs when one progenitor copy of a gene is expressed at a higher level than the other in allopolyploids. Morphological variation, including differences in flower colour, exists between natural and synthetic allopolyploids of Nicotiana tabacum and their progenitors. In this study, we use a comparative transcriptomic approach to investigate gene expression differences as well as homeologue bias in the flavonoid biosynthetic pathway (FBP) in these accessions. We do not observe reciprocal homeologue bias between dark and light pink allopolyploids, but the production of light pink flowers is correlated with high FLAVONOL SYNTHASE:DIHYDROFLAVONOL-4-REDUCTASE (FLS:DFR) ratio at 60% of anthesis length due to delayed activation of DFR in these accessions. We do find that natural allopolyploids have stronger homeologue bias than synthetic allopolyploids in both FBP genes and across the transcriptome. While there is no overall subgenome dominance, there is a bias towards expression of N. tomentosiformis homeologues in FBP genes; however, the magnitude of this bias is reduced in allopolyploids compared to the progenitors, suggesting that N. sylvestris homeologues play an active role in the development of flower colour in N. tabacum allopolyploids. In addition, synthetic allopolyploids tend to exhibit trans regulation of homeologues whereas natural allopolyploids often have evolved cis -regulatory differences between homeologues since their origin. [ABSTRACT FROM AUTHOR]

Anthocyanin pigments are responsible for many of the vivid pink, purple, red, and blue flower colors across angiosperms and frequently vary within and between closely related species. While anthocyanins are well known to influence pollinator attraction, they are also associated with tolerance to abiotic stressors such as extreme temperatures, reduced precipitation, and ultraviolet radiation. Using a comparative approach, we tested whether abiotic variables predict floral anthocyanin in monkeyflowers (Phrymaceae) across western North America. Within two polymorphic species, we found that abiotic variables predicted flower color across their geographic ranges. In Erythranthe discolor, the frequency of pink flowered (anthocyanin producing) individuals was greater in populations with reduced precipitation. In Diplacus mephiticus, the frequency of pink flowered individuals was greater at higher elevations that had reduced precipitation and lower temperatures but less ultraviolet radiation. At the macroevolutionary scale, across two parallel radiations of North American monkeyflowers, species with floral anthocyanins (pink, purple, or red corollas) occupied areas with reduced precipitation in Erythranthe but not Diplacus. However, after accounting for phylogenetic relatedness, we found no evidence for the joint evolution of flower color and environmental affinity in either clade. We conclude that although abiotic stressors may play a role in the evolution of flower color within polymorphic species, we found no evidence that these processes lead to macroevolutionary patterns across monkeyflowers.

Anthocyanin pigments are responsible for many of the vivid pink, purple, red, and blue flower colors across angiosperms and frequently vary within and between closely related species. While anthocyanins are well known to influence pollinator attraction, they are also associated with tolerance to abiotic stressors such as extreme temperatures, reduced precipitation, and ultraviolet radiation. Using a comparative approach, we tested whether abiotic variables predict floral anthocyanin in monkeyflowers (Phrymaceae) across western North America. Within two polymorphic species, we found that abiotic variables predicted flower color across their geographic ranges. In Erythranthe discolor , the frequency of pink flowered (anthocyanin producing) individuals was greater in populations with reduced precipitation. In Diplacus mephiticus , the frequency of pink flowered individuals was greater at higher elevations that had reduced precipitation and lower temperatures but less ultraviolet radiation. At the macroevolutionary scale, across two parallel radiations of North American monkeyflowers, species with floral anthocyanins (pink, purple, or red corollas) occupied areas with reduced precipitation in Erythranthe but not Diplacus. However, after accounting for phylogenetic relatedness, we found no evidence for the joint evolution of flower color and environmental affinity in either clade. We conclude that although abiotic stressors may play a role in the evolution of flower color within polymorphic species, we found no evidence that these processes lead to macroevolutionary patterns across monkeyflowers. [ABSTRACT FROM AUTHOR]

A link between the scent and color of Narcissus tazetta flowers can be anticipated due to their biochemical origin, as well as their similar biological role. Despite the obvious aesthetic and ecological significance of these colorful and fragrant components of the flowers and the molecular profiles of their pigments, fragrant formation has addressed in some cases. However, the regulatory mechanism of the correlation of fragrant components and color patterns is less clear. We simultaneously used one way to address how floral color and fragrant formation in different tissues are generated during the development of an individual plant by transcriptome-based weighted gene co-expression network analysis (WGCNA). A spatiotemporal pattern variation of flavonols/carotenoids/chlorophyll pigmentation and benzenoid/phenylpropanoid/ monoterpene fragrant components between the tepal and corona in the flower tissues of Narcissus tazetta, was exhibited. Several candidate transcription factors: MYB12, MYB1, AP2-ERF, bZIP, NAC, MYB, C2C2, C2H2 and GRAS are shown to be associated with metabolite flux, the phenylpropanoid pathway to the production of flavonols/anthocyanin, as well as related to one branch of the phenylpropanoid pathway to the benzenoid/phenylpropanoid component in the tepal and the metabolite flux between the monoterpene and carotenoids biosynthesis pathway in coronas. It indicates that potential competition exists between floral pigment and floral fragrance during Narcissus tazetta individual plant development and evolutionary development.

Key message An EST-SSR database of Magnolia wufengensis was first generated by transcriptome sequencing, the SSRs related to flower pigment synthesis were validated, and the transferability of the EST-SSR markers to other species was additionally investigated. Magnolia (M.) wufengensis is a distinct ornamental species endemic to China and is famous for its gorgeous flower color. However, the limitation of understanding genetic resources has restricted its conservation and breeding. This study used RNA-Seq to generate thousands of expressed sequence tags (ESTs) with which thousands of functional markers were developed. Of the 9567 simple sequence repeats (SSRs) identified, 8306 contained unigene sequences. Among the different SSR motif types, dinucleotide repeats (50.8%) were the most abundant, followed by trinucleotide repeats (32.4%). AG/CT (37.8%) and AAG/CTT (11.8%) were the most enriched repeat motifs. A total of 5203 EST-SSR novel primer pairs were designed to construct a reference database, from which 33 related to floral pigment formation were PCR-validated by testing them on the five cultivars of M. wufengensis. Twenty-two primer pairs displayed clear PCR products in the verification. Moreover, the number of alleles per marker ranged from 1 to 6 with an average of 3.41, and the polymorphic bands ranged from 0 to 6 with an average of 2.77. Additionally, the genetic distances were positively correlated with certain phenotypic indexes, including anthocyanin and flavonoid contents. Furthermore, applying these EST-SSR markers to other related species showed that 50.0–68.1% of the markers were transferable. The identified EST-SSRs will not only inspire future molecular-assisted breeding in Magnoliaceae but also facilitate targeted research in marker-trait association for floral pigment formation and genetic diversity analysis. [ABSTRACT FROM AUTHOR]

Many of the 'adaptive' traits in angiosperm flowers occur only in some species within a clade. One good example of such traits is floral colour change, that is the retention of old, nonreproductive, rewardless, but fully turgid flowers in an altered colour. This trait has been viewed as a plant strategy to enhance distant pollinator attraction while minimizing visits to nonreproductive flowers. Considering that the same scenario appears true for most visually oriented flower visitors, however, it is unclear why this trait does not prevail in nature., To understand such evolutionary patterns, we conducted a screening search for floral colour change in 219 angiosperm species. We quantified spectral alterations in petals or petaloid organs and translated them into colour shifts through insect eyes. Using phylogeny-based comparative methods, we further explored possibilities accounting for the infrequent occurrences of floral colour change: tendency of related species to resemble each other more than those randomly drawn from the phylogenetic tree (i.e. phylogenetic signal), constraints imposed through pigment coloration and their functions and evolutionary correlates of floral colour change., Ultraviolet-sensitive insect eyes were estimated to perceive floral colour change more often than previously noticed. We detected significant phylogenetic signal in the degree of floral colour change. The evolution of floral colour change appeared constrained by pigment chemistry, because greater changes were more likely to occur in yellow or red floral parts. Postchange colours tended to retain distant visual detectability (i.e. green-receptor contrast), while reducing attractiveness in a close range (i.e. colour contrast), indicating another constraint imposed through the functions of pigment coloration. Data also suggest a possible evolutionary association between floral colour change and bee pollination., Results indicate that floral colour change is scarce in nature because it primarily evolved to accommodate bees or comparable pollinators and because its occurrence was constrained by phylogenetic relatedness, pigment chemistry and ecological functions. An understanding of floral evolution thus requires considering different causalities for trait diversity in an integrative manner. [ABSTRACT FROM AUTHOR]

Abstract: This study uses anthocyanins in the red flowers of section Camellia as taxonomic markers to investigate the phenetic relationships among 33 wild species from China, Taiwan, and Japan. The 25 anthocyanins from section Camellia produced 38 pigment patterns that serve as phenetic markers. Principal Component Analysis (PCA) indicated that the attachment of one or two glucoses to the cyanidin-core structure at the 3- or the 3- and 5-positions, respectively, was the most influential pattern against the first factor, Z 1. In addition, two alternative pigment patterns, acylated or non-acylated, and the structural isomerism (cis- or trans-) of the p-coumaroyl group were relatively significant patterns. Ward’s minimum-variance cluster analysis (WMVCA) produced a dendrogram that consisted of two sub-clusters. One sub-cluster (A) was constructed by species that have mainly two types of anthocyanins: 3,5-di-O-β-glucosides (Camellia saluenensis) and sambubioside of cyanidin (Camellia reticulata). The other sub-cluster (B) was made up of the 3-O-β-glucosides of cyanidin (Camellia japonica) and delphinidin (Camellia hongkongensis), with a higher proportion of the 3-O-β-galactosides (Camellia mairei and Camellia boreali-yunnanica). The former group showed a higher proportion of acylation, over 63%, but with the exception of Camellia azalea. The latter group showed less than 52% acylation, but with the exception of C. hongkongensis and C. boreali-yunnanica. PCA and WMVCA indicated that the greater the amount of di-O-glycosides and acylation, the more primitive anthocyanin traits the species possess. Based on these results, in conjunction with geographical and literary information, the data suggest that the Xinan district is the site/center of origin for the red-flowered Camellia species of which both C. saluenensis and C. reticulata have the most primitive anthocyanin traits. [Copyright &y& Elsevier]

A link between the scent and color of Narcissus tazetta flowers can be anticipated due to their biochemical origin, as well as their similar biological role. Despite the obvious aesthetic and ecological significance of these colorful and fragrant components of the flowers and the molecular profiles of their pigments, fragrant formation has addressed in some cases. However, the regulatory mechanism of the correlation of fragrant components and color patterns is less clear. We simultaneously used one way to address how floral color and fragrant formation in different tissues are generated during the development of an individual plant by transcriptome-based weighted gene co-expression network analysis (WGCNA). A spatiotemporal pattern variation of flavonols/carotenoids/chlorophyll pigmentation and benzenoid/phenylpropanoid/ monoterpene fragrant components between the tepal and corona in the flower tissues of Narcissus tazetta, was exhibited. Several candidate transcription factors: MYB12, MYB1, AP2-ERF, bZIP, NAC, MYB, C2C2, C2H2 and GRAS are shown to be associated with metabolite flux, the phenylpropanoid pathway to the production of flavonols/anthocyanin, as well as related to one branch of the phenylpropanoid pathway to the benzenoid/phenylpropanoid component in the tepal and the metabolite flux between the monoterpene and carotenoids biosynthesis pathway in coronas. It indicates that potential competition exists between floral pigment and floral fragrance during Narcissus tazetta individual plant development and evolutionary development. [ABSTRACT FROM AUTHOR]