Petunia Flowers Research Articles

Identification and mutagenesis of disease susceptibility genes of Petunia hybrida

Hybrid petunia cultivars are susceptible to infection by powdery mildew (Oidium longipes) and potyviruses (potato Y virus, petunia flower mottle virus) during commercial vegetative propagation. Plant proteins encoded by susceptibility genes are required by powdery mildew and potyviruses to infect plant hosts. To examine the potential of developing genetic resistance to these pathogens, petunia orthologs of the susceptibility genes MLO, eIF4E, and eIF(iso)4E were identified and characterized. High-resolution DNA melting analysis was conducted with a population of chemically-mutagenized petunia plants to identify mutations in these genes. Among 865 M2 families, point mutations were detected in coding regions of PhMLO1, but not eIF4E or eIF(iso)4E. One of the point mutations caused a glycine to glutamate substitution that was predicted to have a deleterious effect on PhMLO function. This study demonstrated the potential of TILLING for the development of pathogen resistance in petunia through the loss of susceptibility gene function.

Flowering and Morphological Responses of Petunia and Pansy as Influenced by Lamp Type and Lighting Period to Provide Long Days

Flowering and Morphological Responses of Petunia and Pansy as Influenced by Lamp Type and Lighting Period to Provide Long Days

Growth and Flowering Responses of Petunia to Various Artificial Light Sources with Different Light Qualities

This study was carried out to investigate the effect of artificial light sources with different light qualities on the growth and flowering characteristics of a herbaceous long-day plant, Petunia × hybrida Hort. Seedlings of petunia cultivar ‘Madness Rose’ were potted, acclimated for one week, and grown in a phytotron equipped with tube- and bulb-type fluorescent lamps (FL tube and bulb), tube-type white light-emitting diodes (LED tube), halogen lamps (HL), metal halide lamps (MH), and high pressure sodium lamps (HPS) for 10 weeks. The temperature, photoperiod, and photosynthetic photon flux density (PPFD) in the phytotron were 22 ± 2℃, 16 h, and 25 ±2 μmolㆍm -2 ㆍs -1 , respectively. Light sources combined with HL promoted stem elongation, and plant height and internode length decreased with increasing red to far-red (R:FR) ratio. FL tube + LED tube, HPS, and FL tube promoted branching, whereas plants grown under light sources combined with HL did not have any branches. Days to flowering (from longest to shortest) occurred as follows: FL tube + HL > FL tube + HL > MH > HPS = FL tube + FL bulb > FL tube + LED tube > LED tube > FL tube, indicating that reducing the R:FR ratio of the light sources promoted flowering. Only 20% of plants grown under an FL tube flowered, whereas under all other treatments, 100% of plants flowered. At 10 weeks after treatment, plants grown under HPS and MH had (cumulatively) 12 open flowers, and those grown under FL tube + FL bulb, LED tube, FL tube + LED tube, and HPS treatment had approximately seven flower buds. These results suggest that light sources with low R:FR ratios promote flowering and stem elongation in petunia, but they reduce its ornamental value due to overgrowth and poor branching.

A basic helix-loop-helix transcription factor, PhFBH4, regulates flower senescence by modulating ethylene biosynthesis pathway in petunia.

The basic helix-loop-helix (bHLH) transcription factors (TFs) play important roles in regulating multiple biological processes in plants. However, there are few reports about the function of bHLHs in flower senescence. In this study, a bHLH TF, PhFBH4, was found to be dramatically upregulated during flower senescence. Transcription of PhFBH4 is induced by plant hormones and abiotic stress treatments. Silencing of PhFBH4 using virus-induced gene silencing or an antisense approach extended flower longevity, while transgenic petunia flowers with an overexpression construct showed a reduction in flower lifespan. Abundance of transcripts of senescence-related genes (SAG12, SAG29) was significantly changed in petunia PhFBH4 transgenic flowers. Furthermore, silencing or overexpression of PhFBH4 reduced or increased, respectively, transcript abundances of important ethylene biosynthesis-related genes, ACS1 and ACO1, thereby influencing ethylene production. An electrophoretic mobility shift assay showed that the PhFBH4 protein physically interacted with the G-box cis-element in the promoter of ACS1, suggesting that ACS1 was a direct target of the PhFBH4 protein. In addition, ectopic expression of this gene altered plant development including plant height, internode length, and size of leaves and flowers, accompanied by alteration of transcript abundance of the gibberellin biosynthesis-related gene GA2OX3. Our results indicate that PhFBH4 plays an important role in regulating plant growth and development through modulating the ethylene biosynthesis pathway.

CCoAOMT Down-Regulation Activates Anthocyanin Biosynthesis in Petunia.

Anthocyanins and volatile phenylpropenes (isoeugenol and eugenol) in petunia (Petunia hybrida) flowers have the precursor 4-coumaryl coenzyme A (CoA) in common. These phenolics are produced at different stages during flower development. Anthocyanins are synthesized during early stages of flower development and sequestered in vacuoles during the lifespan of the flowers. The production of isoeugenol and eugenol starts when flowers open and peaks after anthesis. To elucidate additional biochemical steps toward (iso)eugenol production, we cloned and characterized a caffeoyl-coenzyme A O-methyltransferase (PhCCoAOMT1) from the petals of the fragrant petunia 'Mitchell'. Recombinant PhCCoAOMT1 indeed catalyzed the methylation of caffeoyl-CoA to produce feruloyl CoA. Silencing of PhCCoAOMT1 resulted in a reduction of eugenol production but not of isoeugenol. Unexpectedly, the transgenic plants had purple-colored leaves and pink flowers, despite the fact that cv Mitchell lacks the functional R2R3-MYB master regulator ANTHOCYANIN2 and has normally white flowers. Our results indicate that down-regulation of PhCCoAOMT1 activated the anthocyanin pathway through the R2R3-MYBs PURPLE HAZE (PHZ) and DEEP PURPLE, with predominantly petunidin accumulating. Feeding cv Mitchell flowers with caffeic acid induced PHZ expression, suggesting that the metabolic perturbation of the phenylpropanoid pathway underlies the activation of the anthocyanin pathway. Our results demonstrate a role for PhCCoAOMT1 in phenylpropene production and reveal a link between PhCCoAOMT1 and anthocyanin production.

Failure to launch: the self-regulating Md-MYB10 R6 gene from apple is active in flowers but not leaves of Petunia.

The Md - MYB10 R6 gene from apple is capable of self-regulating in heterologous host species and enhancing anthocyanin pigmentation, but the activity of MYB10 is dependent on endogenous protein partners. Coloured foliage due to anthocyanin pigments (bronze/red/black) is an attractive trait that is often lacking in many bedding, ornamental and horticultural plants. Apples (Malus×domestica) containing an allelic variant of the anthocyanin regulator, Md-MYB10 R6 , are highly pigmented throughout the plant, due to autoregulation by MYB10 upon its own promoter. We investigated whether Md-MYB10 R6 from apple is capable of functioning within the heterologous host Petunia hybrida to generate plants with novel pigmentation patterns. The Md-MYB10 R6 transgene (MYB10-R6 pro :MYB10:MYB10 term ) activated anthocyanin synthesis when transiently expressed in Antirrhinum rosea (dorsea) petals and petunia leaf discs. Stable transgenic petunias containing Md-MYB10 R6 lacked foliar pigmentation but had coloured flowers, complementing the an2 phenotype of 'Mitchell' petunia. The absence of foliar pigmentation was due to the failure of the Md-MYB10 R6 gene to self-activate in vegetative tissues, suggesting that additional protein partners are required for Md-MYB10 to activate target genes in this heterologous system. In petunia flowers, where endogenous components including MYB-bHLH-WDR (MBW) proteins were present, expression of the Md-MYB10 R6 promoter was initiated, allowing auto-regulation to occur and activating anthocyanin production. Md-MYB10 is capable of operating within the petunia MBW gene regulation network that controls the expression of the anthocyanin biosynthesis genes, AN1 (bHLH) and MYBx (R3-MYB repressor) in petals.

Two showy traits, scent emission and pigmentation, are finely coregulated by the MYB transcription factor PH4 in petunia flowers.

The mechanism underlying the emission of phenylpropanoid volatiles is poorly understood. Here, we reveal the involvement of PH4, a petunia MYB-R2R3 transcription factor previously studied for its role in vacuolar acidification, in floral volatile emission. We used the virus-induced gene silencing (VIGS) approach to knock down PH4 expression in petunia, measured volatile emission and internal pool sizes by GC-MS, and analyzed transcript abundances of scent-related phenylpropanoid genes in flowers. Silencing of PH4 resulted in a marked decrease in floral phenylpropanoid volatile emission, with a concurrent increase in internal pool levels. Expression of scent-related phenylpropanoid genes was not affected. To identify putative scent-related targets of PH4, we silenced PH5, a tonoplast-localized H(+) -ATPase that maintains vacuolar pH homeostasis. Suppression of PH5 did not yield the reduced-emission phenotype, suggesting that PH4 does not operate in the context of floral scent through regulation of vacuolar pH. We conclude that PH4 is a key floral regulator that integrates volatile production and emission processes and interconnects two essential floral traits - color and scent.

Antagonistic action of blue and red light on shoot elongation in petunia depends on gibberellin, but the effects on flowering are not generally linked to gibberellin

Plant morphology and flowering are influenced by light quality, but responses vary between species. Here we investigated effects of irradiance (70 or 150μmolm−2s−1) of red (R) and blue (B) compared to white (W) light, provided by light emitting diodes, on growth and flowering in petunia. R light inhibited shoot elongation, but opposite to commonly observed, B light greatly enhanced shoot elongation. Consistent with this, bioactive gibberellins (GA1, GA4) showed higher and lower levels under B and R light, respectively, and GA3 application induced elongation in uniconazole-treated plants, although delayed in R. Inhibited shoot elongation under RB treatment in spite of higher GA level compared to R only, supports that R light inhibits elongation growth, and indicates negative effect of R light on GA signaling. Floral bud formation and flowering occurred earlier under B compared to W light. Whereas no floral buds were observed under low R irradiance, high R irradiance and temporal switching to B light during long-term low R irradiance induced floral development. Except slight trends of promoting effect of the highest GA3 level and delay in uniconazole-response under B light, lack of flowering under low R irradiance was not significantly affected by uniconazole or GA3 application. In conclusion, B and R light are strong signals enhancing and inhibiting shoot elongation, respectively, through modulation of GA content. B light is a strong signal in floral bud formation, whereas effect of R light depends on irradiance, indicating existence of an energy/photosynthesis-related floral pathway in petunia. Although light quality affects flowering and main shoot elongation, these responses do probably not correlate with each other through GA synthesis.

Functional characterization of PhGR and PhGRL1 during flower senescence in the petunia

Petunia PhGRL1 suppression accelerated flower senescence and increased the expression of the genes downstream of ethylene signaling, whereas PhGR suppression did not. Ethylene plays an important role in flowers senescence. Homologous proteins Green-Ripe and Reversion to Ethylene sensitivity1 are positive regulators of ethylene responses in tomato and Arabidopsis, respectively. The petunia flower has served as a model for the study of ethylene response during senescence. In this study, petunia PhGR and PhGRL1 expression was analyzed in different organs, throughout floral senescence, and after exogenous ethylene treatment; and the roles of PhGR and PhGRL1 during petunia flower senescence were investigated. PhGRL1 suppression mediated by virus-induced gene silencing accelerated flower senescence and increased ethylene production; however, the suppression of PhGR did not. Taken together, these data suggest that PhGRL1 is involved in negative regulation of flower senescence, possibly via ethylene production inhibition and consequently reduced ethylene signaling activation.

Aromatic Amino Acid Network: Biosynthesis, Regulation and Transport

Aromatic amino acids are essential constituents of proteins in all living organisms, while in plants phenylalanine (Phe) and tyrosine (Tyr) additionally serve as precursors for thousands of specialized compounds that have a profound impact on plant growth, development, reproduction and defense. Plants direct 20‐30% of photosynthetically fixed carbon to the production of Phe and Phe‐derived compounds, which constitute approximately 30‐45% of plant organic matter. Humans are incapable of synthesizing Phe and must primarily obtain it directly or indirectly from plants. Phe biosynthesis in plants occurs via two alternative routes with either arogenate or phenylpyruvate as a key intermediate. Using petunia flowers as a model system, we have shown that plants predominantly synthesize Phe in plastids via the arogenate pathway while they can also utilize the microbial‐like phenylpyruvate pathway. Moreover, flux through the phenylpyruvate route is increased when the entry point to the arogenate pathway is limiting. Interestingly, the phenylpyruvate pathway utilizes a cytosolic aminotransferase that strongly favors Tyr as the amino donor. These results demonstrate that Phe biosynthesis is not limited to plastids and that there is an interconnection between aromatic amino acid catabolism and biosynthesis in planta. Another aspect of plant metabolism to be discussed is its compartmentalization and metabolite transport within the cell and how this intracellular transport contributes to the interconnections between and within metabolic networks.

Red and blue light effects on morphology and flowering of Petunia × hybrida

To investigate the effects of R and B in environments with different FR levels, Petunia×hybrida ‘Tidal wave’ were grown in a greenhouse during early spring (March) and late spring (May) under plastic film transmitting (+FR) and not transmitting far-red light (−FR) in combination with R and B light emitting diodes (LED) as supplementary light placed underneath the films. The main objective of the study was to test the effect of R (600–700nm, peak 660) and B light (400–500nm, peak 450) on morphology and flowering in a FR-deficient greenhouse environment compared with an environment with FR light in different seasons. R light reduced shoot elongation and resulted in more compact plants in both seasons and the combination of –FR and R light resulted in the most compact plants without much delay in flowering. By contrast, the effect of B light was dependent on the natural background light level and the presence of FR light. In early spring when the natural irradiance was low (1.35molm−2h−1), B light promoted stem elongation, caused a more upright shoot orientation, increased plant height and promoted flowering compared to control and R light, whereas in late spring, when the natural irradiance was higher (2.33molm−2h−1), the effect of B light in a FR-deficient environment was not significantly different from R light in the response to stem elongation and flowering.

Characterization of a fertility-related SANT/MYB gene (PhRL) from petunia

The SANT/MYB transcription factors play a critical role in regulating the development of plants. Recently, various SANT/MYB transcription factors have been reported in some plant species, while none in petunia. In this research, a gene containing the SANT/MYB region, designated as PhRL, was firstly identified in petunia flower buds cDNA library. The open-reading frame of PhRL was 288bp, encoding a putative 10.97kDa protein of 95 amino acids. Sequence alignment exhibited that PhRL contained a high conserved SANT/MYB domain. Phylogenetic comparison showed that PhRL was clustered together with AtRL5 and AtRL6 of Arabidopsis. Different from the reported SANT/MYB transcription factors, PhRL was preponderantly expressed in the anther and then in the pistil, with little/no detection in sepal, petal, stem, root or leaf. RNA interference (RNAi) of the PhRL expression in petunia showed significant decrease in pollen viability, and enlargement in size of sex organs. These results indicated that PhRL was a fertility-related gene, which might be involved in both the anther and pistil development of petunia. Studies on PhRL may further our understanding of the molecular mechanisms of sex organs development in petunia.

Possible Role of Sphingolipids in Developmental Programmed Cell Death of Petunia Petals

A type of programmed cell death (PCD) in animals is due to lysosomal membrane permeabilisation or rupture. One of the suggested reasons is sphingolipid accumulation in the membrane. In plants many examples of PCD, including petal senescence, are due to vacuolar permeabilisation and rupture. Using Petunia flowers, we tested the effect on PCD of sphingolipids and of sphinglolipid synthesis inhibitors. Feeding flowers with five main sphingolipids (sphinganine, phytosphingosine, dihydroceramide, ceramide and sphingosine) hastened PCD. Feeding phytosphingosine together with silver thiosulphate, an inhibitor of ethylene perception, completely prevented the PCD-promoting effect of phytosphingosine, suggesting that its acts through ethylene. Feeding together with the reactive oxygen species scavenger N-acetylcysteine had no effect, while the scavenger ascorbic acid only had a slight alleviating effect. These data suggested that phytosphingosine did not act through reactive oxygen species. Treatments with four inhibitors of sphingolipid synthesis (desipramide, fumonisin B1, myriocin, N,Ndimethylsphingosine) hastened PCD. The data indicate that changes in the endogenous sphingolipid levels resulted in early PCD. The effect of phytosphingosine was abrogated by blocking ethylene perception, suggesting that it acted upstream of ethylene, thus not by directly affecting vacuolar membrane composition.

Changes in cis-regulatory elements of a key floral regulator are associated with divergence of inflorescence architectures.

Higher plant species diverged extensively with regard to the moment (flowering time) and position (inflorescence architecture) at which flowers are formed. This seems largely caused by variation in the expression patterns of conserved genes that specify floral meristem identity (FMI), rather than changes in the encoded proteins. Here, we report a functional comparison of the promoters of homologous FMI genes from Arabidopsis, petunia, tomato and Antirrhinum. Analysis of promoter-reporter constructs in petunia and Arabidopsis, as well as complementation experiments, showed that the divergent expression of leafy (LFY) and the petunia homolog aberrant leaf and flower (ALF) results from alterations in the upstream regulatory network rather than cis-regulatory changes. The divergent expression of unusual floral organs (UFO) from Arabidopsis, and the petunia homolog double top (DOT), however, is caused by the loss or gain of cis-regulatory promoter elements, which respond to trans-acting factors that are expressed in similar patterns in both species. Introduction of pUFO:UFO causes no obvious defects in Arabidopsis, but in petunia it causes the precocious and ectopic formation of flowers. This provides an example of how a change in a cis-regulatory region can account for a change in the plant body plan.

Epimutant Induction as a New Plant Breeding Technology

A small interfering RNA (siRNA) can be custom-produced in plant cells when a transgene comprising an inverted-repeat sequence is used to form the corresponding double-stranded (ds)RNA. This siRNA induces methylation of the homologous DNA through the RNA-directed DNA methylation (RdDM) pathway. As methylation of the promoter region causes transcriptional gene silencing (TGS), dsRNA for the promoter sequence of a gene can induce TGS of the gene, accompanied by modification of chromatin. Such epigenetic variation provides a novel technique to induce silencing of a target gene. Furthermore, once epigenetic variation has occurred, the siRNA need not be present to maintain the stable repression of transcription even in the subsequent generation. Thus, the induction of epigenetic changes is a potentially new plant-breeding technology to improve crops. Discipline: Plant breeding Additional key words: DNA methylation, RNA silencing, transcriptional gene silencing, siRNA longdistance transport *Corresponding author: e-mail tharada@cc.hirosakiu.ac.jp Received 10 March 2014; accepted 9 January 2015. Introduction Napoli et al. (1990) and van der Krol et al. (1990) reported an RNA interference (RNAi) phenomenon for the first time. They overexpressed a transgene of chalcone synthase (CHS), a key enzyme in flavonoid biosynthesis and the rate-limiting enzyme in anthocyanin biosynthesis, to generate a darker violet petunia flower, but unexpectedly obtained a white flower. Because the CHS transcription level was 50-fold lower than that in the wild-type flower, they concluded that as well as the transgene, the endogenous CHS gene had also been silenced. A similar phenomenon in a fungus (Neurospora crassa), termed “quelling”, was reported by Romano & Macino (1992). Furthermore, in an animal species (Caenorhabditis elegans), it was reported that introducing sense or antisense RNA of a gene to cells resulted in the mRNA degrading (Guo et al. 1995). Fire et al. (1998), Nobel Prize winner in 2006, clarified the RNAi mechanism by which dsRNA could cause endogenous mRNA to degrade. A number of subsequent studies revealed that dsRNA initiates gene silencing through inhibition at the post-transcriptional level (post-transcriptional gene silencing; PTGS) or the transcriptional level (transcriptional gene silencing; TGS). In the latter case, a small interfering RNA (siRNA) 24 nt long induces methylation of the fifth carbon cytosine residue within the region of sequence identity between the triggering RNA and the homologous DNA (Matzke et al. 2004). Although cytosine methylation is mostly limited to CG dinucleotide sequence contexts in animal genomes, in plants the methylation occurs not only in the symmetrical CG context but also in the CHG and CHH sequence contexts (where H=A, C or T) throughout their genomes. The cytosine methylation of each context is performed by respective methylation enzymes. The process of de novo DNA methylation is triggered by 24 nt siRNAs produced by RdDM. Furthermore, two plant-specific RNA polymerases, PolIV and PolV and the RDR2, DCL3 and AGO4 proteins operate in this pathway (Matzke et al. 2009, Haag & Pikaad 2011). Chemical modifications of DNA influence chromatin structure through histone methylation, while the methylation of histone H3 lysine (H3K9) plays an important role in establishing and maintaining DNA methylation (Grewal & Jia 2007). Epigenetic changes play pivotal roles in the developmental responses of plants. Recent studies have suggested

Manipulation of MKS1 gene expression affects Kalanchoë blossfeldiana and Petunia hybrida phenotypes.

The establishment of alternative methods to chemical treatments for growth retardation and pathogen protection in ornamental plant production has become a major goal in recent breeding programmes. This study evaluates the effect of manipulating MAP kinase 4 nuclear substrate 1 (MKS1) expression in Kalanchoë blossfeldiana and Petunia hybrida. The Arabidopsis thaliana MKS1 gene was overexpressed in both species via Agrobacterium-mediated transformation, resulting in dwarfed phenotypes and delayed flowering in both species and increased tolerance to Pseudomonas syringae pv. tomato in transgenic Petunia plants. The lengths of the stems and internodes were decreased, while the number of nodes in the transgenic plants was similar to that of the control plants in both species. The transgenic Kalanchoë flowers had an increased anthocyanin concentration, and the length of the inflorescence stem was decreased. The morphology of transgenic Petunia flowers was not altered. The results of the Pseudomonas syringae tolerance test showed that Petunia plants with one copy of the transgene reacted similarly to the nontransgenic control plants; however, plants with four copies of the transgene exhibited considerably higher tolerance to bacterial attack. Transgene integration and expression was determined by Southern blot hybridization and RT-PCR analyses. MKS1 in wild-type Petunia plants was down-regulated through a virus-induced gene silencing (VIGS) method using tobacco rattle virus vectors. There were no significant phenotypic differences between the plants with silenced MKS1 genes and the controls. The relative concentration of the MKS1 transcript in VIGS-treated plants was estimated by quantitative RT-PCR.

Vacuolar proton pumping: more than the sum of its parts?

Petunia flower colour is dependent on vacuolar pH and is therefore used to study acidification mechanisms. Recently, it was shown that the concerted action of two tonoplast-localised P3-ATPases is required to hyperacidify vacuoles of petunia petal epidermis cells. Here we discuss how steep cross-tonoplast pH gradients may be established in specific cells.

A Petunia Homeodomain-Leucine Zipper Protein, PhHD-Zip, Plays an Important Role in Flower Senescence

Flower senescence is initiated by developmental and environmental signals, and regulated by gene transcription. A homeodomain-leucine zipper transcription factor, PhHD-Zip, is up-regulated during petunia flower senescence. Virus-induced gene silencing of PhHD-Zip extended flower life by 20% both in unpollinated and pollinated flowers. Silencing PhHD-Zip also dramatically reduced ethylene production and the abundance of transcripts of genes involved in ethylene (ACS, ACO), and ABA (NCED) biosynthesis. Abundance of transcripts of senescence-related genes (SAG12, SAG29) was also dramatically reduced in the silenced flowers. Over-expression of PhHD-Zip accelerated petunia flower senescence. Furthermore, PhHD-Zip transcript abundance in petunia flowers was increased by application of hormones (ethylene, ABA) and abiotic stresses (dehydration, NaCl and cold). Our results suggest that PhHD-Zip plays an important role in regulating petunia flower senescence.

A Research Strategy to Understand the Mechanisms that Govern Flower Color Pattern Formation

The coloration pattern of flower tissue affects the commercial potential of floricultural plants and is also a subject of fundamental biological interest. Transposon insertion or excision and post-transcriptional gene-silencing are well-studied mechanisms involved when flower color patterns form. In this paper, I present a research strategy to understand the mechanisms that govern the formation of flower color patterns. First, I discuss the significance of flower color pattern-formation research and then go on to describe a research system in the following six sections: Observation of flower patterns, Comparison of pigment components, Gene expression analysis, Regulation of target gene expression, Genomic structure, and Factors that can change color pattern-formation. In these sections, reference is made to my own studies on the marginal picotee pattern of Petunia flowers. Post-transcriptional gene-silencing of the chalcone synthase gene is responsible for the formation of white tissue in the white marginal picotee pattern in Petunia flowers. The unusual genomic structure of chalcone synthase is probably related to the operation of position-specific post-transcriptional gene-silencing. In the colored marginal picotee pattern of Petunia flowers, the higher expression of flavonol synthase is a responsible for the central white tissue formation. I also provide a research perspective from which to resolve the remaining questions.

Bioinformatics Analysis of Phenylacetaldehyde Synthase (PAAS), a Protein Involved in Flower Scent Production, in Rose

Rose flowers produce and emit the aromatic volatiles 2-phenylacetaldehyde (PAA) and 2-phenylethanol (2-PE), which have a distinctive flowery/rose-like scent. Previous studies of rose have shown that, similar to Petunia flowers, PAA is formed from L-phenylalanine via pyridoxal-5'-phosphate-dependent L-aromatic amino acid decarboxylase. Rosa phenylacetaldehyde synthase sequence (RhPAAS) is homologous to Petunia phenylacetaldehyde synthase (PhPAAS). Since there is not much experimental data available about different structural properties of that PAAS protein, in the present investigation, we studied the different structural properties of the PAAS protein in petunia and rose using bioinformatics tools. The features of the first, secondary and tertiary structures of this protein were compared between Petunia and Rose. The results indicated that the frequency of negatively charged, Leucine, and frequency of the Ser-Leu, Pro-Glu , Phe-Ser and the, Thr-Thr dipeptides in petunia are more than those in Rose. In contrast, in petunia, the frequencies of hydrophobic and hydrophilic residues, α-helix, β-sheet, β-strands of petunia are lower than those in rose. The features achieved in this study may also provide useful clues for designing scent production pathways using protein engineering techniques.