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Morphology and ontogeny of reproductive structures in Cysticapnos vesicaria. (A) Branching architecture and naming system for inflorescence position. Inflorescences are circled in blue. (B, C) Details of the inflorescence. (C) Black, last foliage leaf preceding the terminal inflorescence; dark grey, terminal inflorescence , corresponding to 'T' in (A). Three flowers are subtended by bracts b1–b3. The pin-like inflorescence apex is marked with a blue arrowhead; light grey, sympodial shoot and inflorescence arising from the foliage leaf axil, corresponding to 'A' in (A). (D –G) SEM micrographs of inflorescence ontogeny. (D) Pin-like ending of the mature inflorescence axis that may be preceded by an empty bract. (E) Two-flowered inflorescence; subtending bracts b1 and b2 removed. Perianth organs are labelled. (F) Terminal inflorescence with bracts b1 and b2 subtending flowers. Bract three is empty; inflorescence apex not visible. Sympodial inflorescence in the axil of the last foliage leaf is framed and shown enlarged in (G). (G) Early-stage inflorescence with three flower primordia. The inflorescence apex is still meristematic. Abbreviations: b1–b3, consecutive bracts; fp1–fp3, consecutive flower primordia; ia, inflorescence apex; ip, inner petal; op, outer petal; pe, pedicel; s, sepal. Scale bars: (D, F) ¼ 500 mm, (E) ¼ 250 mm, (G) ¼ 200 mm.
Source publication
Studies of evolutionary diversification in the basal eudicot family Papaveraceae, such as the transition from actinomorphy to zygomorphy, are hampered by the lack of comparative functional studies. So far, gene silencing methods are only available in the actinomorphic species Eschscholzia californica and Papaver somniferum. This study addresses the...
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... formation of the primary terminal inflorescence ( Fig. 2A), sympodial branching from the axils of the preceding one or two foliage leaves gives rise to higher order inflores- cences ( Fig. 2A). The inflorescence is sessile, with a short internode below the first bract and flower (Fig. 2B,C). Inflorescence bracts are small, scarious and lanceolate. Flowers cluster in a raceme of 1 -3 ...
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... formation of the primary terminal inflorescence ( Fig. 2A), sympodial branching from the axils of the preceding one or two foliage leaves gives rise to higher order inflores- cences ( Fig. 2A). The inflorescence is sessile, with a short internode below the first bract and flower (Fig. 2B,C). Inflorescence bracts are small, scarious and lanceolate. Flowers cluster in a raceme of 1 -3 light-pink, zygomorphic flowers. The small number of flowers identifies our accession as Cysticapnos vesicaria subspecies vesicaria ( Manning et ...
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... formation of the primary terminal inflorescence ( Fig. 2A), sympodial branching from the axils of the preceding one or two foliage leaves gives rise to higher order inflores- cences ( Fig. 2A). The inflorescence is sessile, with a short internode below the first bract and flower (Fig. 2B,C). Inflorescence bracts are small, scarious and lanceolate. Flowers cluster in a raceme of 1 -3 light-pink, zygomorphic flowers. The small number of flowers identifies our accession as Cysticapnos vesicaria subspecies vesicaria ( Manning et al., 2009). A pin-like structure forms the end of the inflor- escence axis, and is sometimes ...
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... bracts are small, scarious and lanceolate. Flowers cluster in a raceme of 1 -3 light-pink, zygomorphic flowers. The small number of flowers identifies our accession as Cysticapnos vesicaria subspecies vesicaria ( Manning et al., 2009). A pin-like structure forms the end of the inflor- escence axis, and is sometimes preceded by an empty bract (Fig. 2D). Flowers initiate in a rapid sequence (Fig. 2G), and the sequence of maturation (Fig. 2E, F) and effloration (Fig. 2B) is acropetal. The calyx consists of two scale-like sepals that resemble bracts and are, like bracts, persistent (Fig. 3A). The corolla is composed of four petals in two whorls. Sepals are initiated in a medial ...
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... Flowers cluster in a raceme of 1 -3 light-pink, zygomorphic flowers. The small number of flowers identifies our accession as Cysticapnos vesicaria subspecies vesicaria ( Manning et al., 2009). A pin-like structure forms the end of the inflor- escence axis, and is sometimes preceded by an empty bract (Fig. 2D). Flowers initiate in a rapid sequence (Fig. 2G), and the sequence of maturation (Fig. 2E, F) and effloration (Fig. 2B) is acropetal. The calyx consists of two scale-like sepals that resemble bracts and are, like bracts, persistent (Fig. 3A). The corolla is composed of four petals in two whorls. Sepals are initiated in a medial position, in one plane with the subtending bract (Fig. ...
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... zygomorphic flowers. The small number of flowers identifies our accession as Cysticapnos vesicaria subspecies vesicaria ( Manning et al., 2009). A pin-like structure forms the end of the inflor- escence axis, and is sometimes preceded by an empty bract (Fig. 2D). Flowers initiate in a rapid sequence (Fig. 2G), and the sequence of maturation (Fig. 2E, F) and effloration (Fig. 2B) is acropetal. The calyx consists of two scale-like sepals that resemble bracts and are, like bracts, persistent (Fig. 3A). The corolla is composed of four petals in two whorls. Sepals are initiated in a medial position, in one plane with the subtending bract (Fig. 2E, F). Upon anthesis, pedicel torsion ...
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... small number of flowers identifies our accession as Cysticapnos vesicaria subspecies vesicaria ( Manning et al., 2009). A pin-like structure forms the end of the inflor- escence axis, and is sometimes preceded by an empty bract (Fig. 2D). Flowers initiate in a rapid sequence (Fig. 2G), and the sequence of maturation (Fig. 2E, F) and effloration (Fig. 2B) is acropetal. The calyx consists of two scale-like sepals that resemble bracts and are, like bracts, persistent (Fig. 3A). The corolla is composed of four petals in two whorls. Sepals are initiated in a medial position, in one plane with the subtending bract (Fig. 2E, F). Upon anthesis, pedicel torsion reorients the flower so that ...
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... sequence (Fig. 2G), and the sequence of maturation (Fig. 2E, F) and effloration (Fig. 2B) is acropetal. The calyx consists of two scale-like sepals that resemble bracts and are, like bracts, persistent (Fig. 3A). The corolla is composed of four petals in two whorls. Sepals are initiated in a medial position, in one plane with the subtending bract (Fig. 2E, F). Upon anthesis, pedicel torsion reorients the flower so that sepals assume a lateral position and the spurred outer petal is positioned upward (Figs 2B and 3A). Outer petals are identical at earlier developmental stages while in the lateral position (Fig. 2E), and epidermal cell shape remains similar even after zygomorphy establishment ...
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... are initiated in a medial position, in one plane with the subtending bract (Fig. 2E, F). Upon anthesis, pedicel torsion reorients the flower so that sepals assume a lateral position and the spurred outer petal is positioned upward (Figs 2B and 3A). Outer petals are identical at earlier developmental stages while in the lateral position (Fig. 2E), and epidermal cell shape remains similar even after zygomorphy establishment (data not shown). ...
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... Sepals are initiated in a medial position, in one plane with the subtending bract (Fig. 2E, F). Upon anthesis, pedicel torsion reorients the flower so that sepals assume a lateral position and the spurred outer petal is positioned upward (Figs 2B and 3A). Outer petals are identical at earlier developmental stages while in the lateral position (Fig. 2E), and epidermal cell shape remains similar even after zygomorphy establishment (data not shown). Inner petals are free at the base and partly connate at their tips, and have a translucent abaxial ridge (Fig. 3A). The androe- cium consists of six stamens in two bundles, and the bicarpel- late gynoecium consists of a many-ovuled ovary, a ...
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... Papaveraceae (e.g. Busch and Gleissberg, 2003;Groot et al., 2005;Carlson et al., 2006;Drea et al., 2007;Orashakova et al., 2009;Yellina et al., 2010;Hands et al., 2011). Vegetative shoot apices hybridized with an anti- sense CvH4 RNA probe strongly labelled CvH4 transcripts in individual cells in the shoot apical meristem and developing leaves ( Supplementary Data Fig. S2), as expected ( Groot et al., 2005). Neighbouring cells remained unstained, demon- strating a good signal-to-background ...
Citations
... Disymmetry (not to be confused with dissymmetry, which means without symmetry) is rare in angiosperms (Citerne et al., 2010) and seen in Papaveraceae as an intermediate state between actinomorphy and zygomorphy (Damerval and Nadot, 2007;Sauquet et al., 2015). Additionally, molecular tools for functional validation have been developed for both actinomorphic and zygomorphic representatives, thus enabling comparative studies (Hidalgo et al., 2012;Zhao et al., 2018) and further establishing Papaveraceae as a model system for the study of floral evolution. ...
Reconstructing evolutionary trajectories and transitions that have shaped floral diversity relies heavily on the phylogenetic framework on which traits are modelled. In this study, we focus on the angiosperm order Ranunculales, sister to all other eudicots, to unravel higher-level relationships, especially those tied to evolutionary transitions in flower symmetry within the family Papaveraceae. This family presents an astonishing array of floral diversity, with actinomorphic, disymmetric (two perpendicular symmetry axes), and zygomorphic flowers. We generated nuclear and plastid datasets using the Angiosperms353 universal probe set for target capture sequencing (of 353 single-copy nuclear ortholog genes), together with publicly available transcriptome and plastome data mined from open-access online repositories. We relied on the fossil record of the order Ranunculales to date our phylogenies and to establish a timeline of events. Our phylogenomic workflow shows that nuclear-plastid incongruence accompanies topological uncertainties in Ranunculales. A cocktail of incomplete lineage sorting, post-hybridization introgression, and extinction following rapid speciation most likely explain the observed knots in the topology. These knots coincide with major floral symmetry transitions and thus obscure the order of evolutionary events.
... In recent years, researchers have utilized VIGS technology to silence hexaploid genes in wheat (Zhang et al. 2017). Using the TRV mediated VIGS system to study the symmetry, inflorescence certainty, and other diverse traits of flowers in the Papaveriaceae family (Hidalgo et al. 2012). The virus-induced gene silencing (VIGS) of SlMYB12 in tomatoes showed similar results as described in this work, with significantly reduced levels of flavonol, rutin, and naringin chalcone in the VIGS silencing region of SlMYB12 (Wang et al. 2018). ...
The cytochrome P450 superfamily of monooxygenases plays a major role in the evolution and diversifcation of plant
natural products. The function of cytochrome P450s in physiological adaptability, secondary metabolism, and xenobiotic
detoxifcation has been studied extensively in numerous plant species. However, their underlying regulatory mechanism in
safflower still remained unclear. In this study, we aimed to elucidate the functional role of a putative CtCYP82G24-encoding
gene in safflower, which suggests crucial insights into the regulation of methyl jasmonate-induced favonoid accumulation
in transgenic plants. The results showed that methyl jasmonate (MeJA) was associated with a progressive upregulation of
CtCYP82G24 expression in safflower among other treatment conditions including light, dark, and polyethylene glycol (PEG).
In addition, transgenic plants overexpressing CtCYP82G24 demonstrated increased expression level of other key favonoid
biosynthetic genes, such as AtDFR, AtANS, and AtFLS, and higher content of favonoid and anthocyanin accumulation when
compared with wild-type and mutant plants. Under exogenous MeJA treatment, the CtCYP82G24 transgenic overexpressed
lines showed a signifcant spike in favonoid and anthocyanin content compared with wild-type and mutant plants. Moreover, the virus-induced gene silencing (VIGS) assay of CtCYP82G24 in safflower leaves exhibited decreased favonoid and
anthocyanin accumulation and reduced expression of key favonoid biosynthetic genes, suggesting a possible coordination
between transcriptional regulation of CtCYP82G24 and favonoid accumulation. Together, our fndings confrmed the likely
role of CtCYP82G24 during MeJA-induced favonoid accumulation in safflower
... VIGS is a well-established method for gene knockdown in angiosperms and has provided insight in determining the mechanisms underlying differences across diverse lineages such as Ranunculales, asterids, Caryophyllales, and rosids. It remains a powerful tool to address questions about organ identity, sex determination, induction of flowering, and compound leaf development (Hidalgo et al., 2012;Hsieh et al., 2013;Fujita et al., 2019). As such, the major goal of this study was to establish VIGS in Cleomaceae, which is garnering interest as a model family (Bayat et al., 2018). ...
Premise:
Cleomaceae is emerging as a promising family to investigate a wide range of phenomena, such as C4 photosynthesis and floral diversity. However, functional techniques are lacking for elucidating this diversity. Herein, we establish virus-induced gene silencing (VIGS) as a method of generating functional data for Cleome violacea, bolstering Cleomaceae as a model system.
Methods:
We leveraged the sister relationship of Cleomaceae and Brassicaceae by using constructs readily available for Arabidopsis thaliana to provide initial information about the feasibility of VIGS in C. violacea. We then developed endogenous constructs to optimize VIGS efficiency and viability for fruit development.
Results:
PHYTOENE DESATURASE was successfully downregulated in C. violacea using both heterologous and endogenous constructs. The endogenous construct had the highest degree of downregulation, with many plants displaying strong photobleaching. FRUITFULL-treated plants were also successfully downregulated, with a high rate of survival but less effective silencing; only a small percentage of survivors showed a strong phenotype.
Discussion:
Our optimized VIGS protocol in C. violacea enables functional gene analyses at different developmental stages. Additionally, C. violacea is amenable to heterologous knockdown, which suggests that a first pass using non-endogenous constructs is a possible route to test additional species of Cleomaceae.
... In recent years, various virus vectors, such as the tobacco mosaic virus (TMV) (Hiriart et al. 2003), satellite virusinduced silencing system (SVISS) (Gosselé et al. 2003), potato virus X (PVX) (Faivrerampant et al. 2004), barley stripe mosaic virus (BSMV) (Holzberg et al. 2010), Cotton leaf crumple virus (CLCrV) (Richard et al. 2012), African cassava mosaic virus (ACMV) (Fauquet et al. 1988;Beyene et al. 2017), tobacco rattle virus (TRV) (Burch-Smith et al. 2006), cabbage leaf crumple virus (CaLCuV) (Tang et al. 2013;Chen et al. 2015), and turnip yellow mosaic virus (TYMV) (Yu et al. 2018), have been successfully used in VIGS. Among them, TRV has the widest host range and induces mild viral symptoms after infecting either dicotyledonous and monocotyledonous plants (Burch-Smith et al. 2004;Chen et al. 2004;Liu et al. 2004;Hidalgo et al. 2012;Fernández-Calvino et al. 2016;Zhang et al. 2017). Each virus vector has a certain host range, and their effects on inducing silencing differ. ...
Main conclusion:
CaLCuV-based VIGS effectively works in cabbage and contributes to efficient functional genomics research in Brassica crop species. Virus-induced gene silencing (VIGS), a posttranscriptional gene silencing method, is an effective technique for analysing the functions of genes in plants. However, no VIGS vectors have been available for Brassica oleracea until now. Here, tobacco rattle virus (TRV), pTYs and cabbage leaf curl virus (CaLCuV) gene-silencing vectors (PCVA/PCVB) were chosen to improve the VIGS system in cabbage using the phytoene desaturase (PDS) gene as an efficient visual indicator of VIGS. We successfully silenced the expression of PDS and observed photobleaching phenomena in cabbage in response to pTYs and CaLCuV, with the latter being more easy to operate and less expensive. The parameters potentially affecting the silencing efficiency of VIGS by CaLCuV in cabbage, including the targeting fragment strategy, inoculation method and incubation temperature, were then compared. The optimized CaLCuV-based VIGS system involves the following: an approximately 500 bp insert sequence, an Agrobacterium OD600 of 1.0, use of the vacuum osmosis method applied at the bud stage, and an incubation temperature of 22 °C. Using these parameters, we achieved a stable silencing efficiency of 65%. To further test the effectiveness of the system, we selected the Mg-chelatase H subunit (ChlH) gene in cabbage and knocked down its expression, and we observed yellow leaves, as expected. We successfully applied the CaLCuV-based VIGS system to two other representative Brassica crop species, B. rapa and B. nigra, and thus expanded the application scope of this system. Our VIGS system described here will contribute to efficient functional genomics research in Brassica crop species.
... Here, it is important to note that most of the cereal orthologs are merely retrieved by phylogenetic analysis from resource genome databases; therefore, specified experimental studies will be required to support genetic framework of underlying mechanisms of floral organ identity in cereals. In this perspective, genome editing tools such as virus-induced gene silencing (VIGS) and clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 system has been widely useful in several eudicots and monocot species to investigate gene function in floral organ identity and symmetry between basal and core eudicots [177][178][179][180][181]. Effective application of these systems could herald a new generation of multidisciplinary evo-devo research that better describes the evolutionary changes in gene regulatory networks underlying floral development. ...
Grasses represent a major family of monocots comprising mostly cereals. When compared to their eudicot counterparts, cereals show a remarkable morphological diversity. Understanding the molecular basis of floral organ identity and inflorescence development is crucial to gain insight into the grain development for yield improvement purposes in cereals, however, the exact genetic mechanism of floral organogenesis remains elusive due to their complex inflorescence architecture. Extensive molecular analyses of Arabidopsis and other plant genera and species have established the ABCDE floral organ identity model. According to this model, hierarchical combinatorial activities of A, B, C, D, and E classes of homeotic genes regulate the identity of different floral organs with partial conservation and partial diversification between eudicots and cereals. Here, we review the developmental role of A, B, C, D, and E gene classes and explore the recent advances in understanding the floral development and subsequent organ specification in major cereals with reference to model plants. Furthermore, we discuss the evolutionary relationships among known floral organ identity genes. This comparative overview of floral developmental genes and associated regulatory factors, within and between species, will provide a thorough understanding of underlying complex genetic and molecular control of flower development and floral organ identity, which can be helpful to devise innovative strategies for grain yield improvement in cereals.
... Among these viruses, TRV has a wide host range and mild infection symptoms. Thus, it has been widely used to construct VIGS vectors to characterize gene function in dicotyledons ( Chung et al., 2004;Fu et al., 2005;Burch-Smith et al., 2006;Hidalgo et al., 2012;Liu et al., 2012 ) and in several species of monocotyledons ( Zhong et al., 2014;Zhang et al., 2017 ). Systemic viral infection is essential for the successful application of VIGS. ...
Gene function analysis is challenging for Lilium due to the lack of an efficient method for stable genetic transformation. Virus-induced gene silencing (VIGS) is an attractive tool for determining gene function in plants. This study reported that Tobacco rattle virus (TRV)-based VIGS of a PHYTOENE DESATURASE (PDS) ortholog (LhPDS) can be achieved in Lilium × formolongi seedlings, with a survival rate of 92%, using the inoculation method of rubbing plus injection. Compared with untreated and mock-treated seedlings, the photobleached leaf phenotype of silenced plants significantly correlates with down-regulation of endogenous LhPDS (P ≤ 0.05). In addition, the silencing phenomenon can be observed in the growing points of plants, indicating that systemic viral infection was achieved using the protocol. The results indicate that TRV-based VIGS can be used to characterize gene function in Lilium × formolongi. This work lays the foundation for gene function analysis and molecular breeding in Lilium spp.
... Ranunculales include several model species that are susceptible to functional genetics by virus-induced gene silencing (VIGS). Among these are the Papaveraceae representatives Papaver somniferum (Hileman et al., 2005), Eschscholzia californica (Wege et al., 2007) and Cysticapnos vesicaria (Hidalgo et al., 2012), and, in Ranunculaceae, Aquilegia coerulea (Gould & Kramer, 2007), Thalictrum ssp. (Di Stilio et al., 2010) and Nigella damascena (Gonc ßalves et al., 2013). ...
... Gene-specific probes were synthesized using a PCR-amplified fragment of the given gene with primers containing a few extra nucleotides (uppercase letters) and a T7 overhang (lowercase letters) (CAtaatacgactcactataGGG) at the 5 0 -end (Table S1), and labeled using a DIG RNA Labeling Kit (Roche). Sample fixation, sectioning and hybridization were performed as described in Orashakova et al. (2009) for E. californica and in Hidalgo et al. (2012) for C. vesicaria. Signals were recorded using a Leitz Laborlux S microscope equipped with a Leica DFC420 C digital camera (Wetzlar, Germany). ...
... The Agrobacterium tumefaciens strain pGV3101 was used for transformation. Cysticapnos seedlings with three to five leaves were inoculated by syringe infiltration as described in Hidalgo et al. (2012). Ten to 17 plants were treated and, for each plant, 30 flowers were phenotypically analyzed in double VIGS treatments (Table S4). ...
Angiosperms possess enormous morphological variation in plant architectures and floral forms. Previous studies in Pentapetalae and monocots have demonstrated the involvement of TCP domain CYCLOIDEA/TEOSINTE BRANCHED1 ‐like ( CYC / TB1 ) genes in the control of floral symmetry and shoot branching. However, how TCP/CYC ‐like ( CYL ) genes originated, evolved and functionally diversified remain unclear.
We conducted a comparative functional study in Ranunculales, the sister lineage to all other eudicots, between Eschscholzia californica and Cysticapnos vesicaria , two species of Papaveraceae with actinomorphic and zygomorphic flowers, respectively.
Phylogenetic analysis indicates that CYL genes in Papaveraceae form two paralogous lineages, PapaCYL1 and PapaCYL2 . Papaveraceae CYL genes show highly diversified expression patterns as well as functions. Enhanced branching by silencing of EscaCYL1 suggests that the role of CYC/TB1 ‐like genes in branching control is conserved in Papaveraceae. In contrast to the arrest of stamen development in Pentapetalae, PapaCYL genes promote stamen initiation and growth. In addition, we demonstrate that CyveCYL s are involved in perianth development, specifying sepal and petal identity in Cysticapnos by regulating the B‐class floral organ identity genes. Our data also suggest the involvement of CyveCYL genes in the regulation of flower symmetry in Cysticapnos .
Our work provides evidence of the importance of TCP/CYC ‐like genes in the promotion of morphological diversity across angiosperms.
... A single study was conducted with a tendrilled species in Papaveraceae. This study documented intermediate stages between leaflets and tendrils in the leaf distal domain of Cysticapnos vesicaria, confirming the origin of tendrils in this family (Hidalgo et al., 2012). No data is available for other tendrilled species within Papaveraceae (see Table 1), or Naravelia (Ranunculaceae). ...
Climbers are abundant in tropical forests, where they constitute a major functional plant type. The acquisition of the climbing habit in angiosperms constitutes a key innovation. Successful speciation in climbers is correlated with the development of specialized climbing strategies such as tendrils, i.e., filiform organs with the ability to twine around other structures through helical growth. Tendrils are derived from a variety of morphological structures, e.g., stems, leaves, and inflorescences, and are found in various plant families. In fact, tendrils are distributed throughout the angiosperm phylogeny, from magnoliids to asterids II, making these structures a great model to study convergent evolution. In this study, we performed a thorough survey of tendrils within angiosperms, focusing on their origin and development. We identified 17 tendril types and analyzed their distribution through the angiosperm phylogeny. Some interesting patterns emerged. For instance, tendrils derived from reproductive structures are exclusively found in the Core Eudicots, except from one monocot species. Fabales and Asterales are the orders with the highest numbers of tendrilling strategies. Tendrils derived from modified leaflets are particularly common among asterids, occurring in Polemoniaceae, Bignoniaceae, and Asteraceae. Although angiosperms have a large number of tendrilled representatives, little is known about their origin and development. This work points out research gaps that should help guide future research on the biology of tendrilled species. Additional research on climbers is particularly important given their increasing abundance resulting from environmental disturbance in the tropics.
... Because loss-of-function mutants are not readily available for most non-model plants, we utilise virus-induced gene silencing (VIGS) to assay gene function. The technique has increasingly been used in evolutionary developmental biology (evo-devo) studies (e.g., [3,5,25,[29][30][31][32][33][34][35][36] to downregulate a number of protein coding genes implicated in floral development where stable transformation protocols are not available [37][38][39]. VIGS facilitates the downregulation of either individual or multiple genes simultaneously [29,[39][40][41]; and, recently, it has been shown capable of knocking down epigenetic modifiers involved in RNA-directed DNA methylation in Arabidopsis [42]. ...
... VIGS generally results in mosaic phenotypes with large amounts of variation across knockdowns [39-41, 46, 47]. In examining floral shape and symmetry, interpreting these variable results can be complex; thus, a reporter gene is often simultaneously knocked down in conjunction with the gene(s) of interest (GOI) to verify successful inoculation, and presumably downregulation [30,37,48]. One often targeted reporter gene in floral tissues is ANTHOCYANIDIN SYNTHASE (ANS; [3,37,49,50]), which is an enzyme that plays a key biochemical role in each of the three major anthocyanin pathways of land plants [51]. ...
Background
While floral symmetry has traditionally been assessed qualitatively, recent advances in geometric morphometrics have opened up new avenues to specifically quantify flower shape and size using robust multivariate statistical methods. In this study, we examine, for the first time, the ability of geometric morphometrics to detect morphological differences in floral dorsoventral asymmetry following virus-induced gene silencing (VIGS). Using Fedia graciliflora Fisch. & Meyer (Valerianaceae) as a model, corolla shape of untreated flowers was compared using canonical variate analysis to knockdown phenotypes of CYCLOIDEA2A (FgCYC2A), ANTHOCYANIDIN SYNTHASE (FgANS), and empty vector controls.
Results
Untreated flowers and all VIGS treatments were morphologically distinct from each other, suggesting that VIGS may cause subtle shifts in floral shape. Knockdowns of FgCYC2A were the most dramatic, affecting the position of dorsal petals in relation to lateral petals, thereby resulting in more actinomorphic-like flowers. Additionally, FgANS knockdowns developed larger flowers with wider corolla tube openings.
Conclusions
These results provide a method to quantify the role that specific genes play in the developmental pathway affecting the dorsoventral axis of symmetry in zygomorphic flowers. Additionally, they suggest that ANS may have an unintended effect on floral size and shape.
... Similar evolutionary changes are reported in comparisons of whole [20,85,87,88]. Much progress has been made in our understanding of floral developmental genetics in Ranunculales [78,[89][90][91][92][93][94], but the basal eudicot grade has not been representatively studied to date. The available data suggest that genetic programmes for floral organ identity are often more broadly deployed in the flowers of non-Pentapetalae angiosperms than in the flowers of Pentapetalae. ...
A salient feature of flowering plant diversification is the emergence of a novel
suite of floral features coinciding with the origin of the most species-rich lineage,
Pentapetalae. Advances in phylogenetics, developmental genetics and
genomics, including new analyses presented here, are helping to reconstruct
the specific evolutionary steps involved in the evolution of this clade. The enormous
floral diversity among Pentapetalae appears to be built on a highly
conserved ground plan of five-parted (pentamerous) flowers with whorled
phyllotaxis. By contrast, lability in the number and arrangement of component
parts of the flower characterize the early-diverging eudicot lineages subtending
Pentapetalae. The diversification of Pentapetalae also coincides closely
with ancient hexaploidy, referred to as the gamma whole-genome triplication,
for which the phylogenetic timing, mechanistic details and molecular evolutionary
consequences are as yet not fully resolved. Transcription factors
regulating floral development often persist in duplicate or triplicate in
gamma-derived genomes, and both individual genes andwhole transcriptional
programmes exhibit a shift from broadly overlapping to tightly defined
expression domains in Pentapetalae flowers. Investigations of these changes
associated with the origin of Pentapetalae can lead to a more comprehensive
understanding of what is arguably one of the most important evolutionary
diversification events within terrestrial plants.
