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Although the petals of Rosa rugosa are rich in flavonoids and their bioactivity has a significant impact on human health, the flavonoid content decreases during flower development. In this study, R. rugosa 'Feng hua' was used to investigate the effects of the melatonin foliar spray on enhancing the quality of rose by focusing on major flavonoids. The results showed that the contents of total flavonoids in rose petals at the full bloom stage induced by melatonin obeyed a bell-shaped curve, with a maximum at 0.3 mM, indicating the concentration-dependent up-regulation of flavonoid biosynthesis. In the treatment with 0.3 mM melatonin, metabolomic analyses showed that the concentrations of ten main flavonoids were identified to be increased by melatonin induction, with high levels and increases observed in three flavonols and two anthocyanins. KEGG enrichment of transcriptomic analysis revealed a remarkable enrichment of DEGs in flavonoid and flavonol biosynthesis, such as Rr4CL , RrF3H , and RrANS . Furthermore, functional validation using virus-induced gene silencing technology demonstrated that Rr4CL3 is the crucial gene regulating flavonoid biosynthesis in response to the stimulant of melatonin. This study provides insights into the exogenous melatonin regulation mechanism of biosynthesis of flavonoids, thereby offering potential industrial applications.

Rose flowers (Rosa hybrida L.) are highly perishable and have a limited vase life. This study evaluated the effects of preharvest foliar applications of γ-aminobutyric acid (GABA) and calcium chloride (CaCl 2 ), individually and combined, on antioxidant responses and vase life of cut Jumilia rose flowers. Treatments included foliar sprays of GABA at 0, 20, 40, and 60 mM and CaCl 2 at 0, 0.75%, and 1.5%, applied in a factorial design within a completely randomized setup before harvest. Results showed GABA and CaCl 2 interaction (especially, 60 mM GABA and 1.5% CaCl 2 ) significantly increased enzymatic antioxidants including superoxide dismutase, catalase, and peroxidase, as well as non-enzymatic antioxidants such as flavonoids, carotenoids, phenolics, and antioxidant activity in petals compared to control. SOD activity in roses, treated with CaCl 2 (1.5%) and GABA (60 mM), peaked at 7.86 units. mg -1 protein min -1 , showing a nearly 2.93-fold increase over the control (2.68 units. mg -1 protein min -1 ). A parallel trend was observed for CAT activity. These treatments also reduced petal malondialdehyde content and polyphenol oxidase activity. Protein content and vase life duration increased in all treatments. Plants treated with a combination of GABA (20 mM) and CaCl 2 (0.75%), GABA (60 mM) and CaCl 2 (1.5%), or GABA (40 mM) individually exhibited the longest vase life duration. The co-application of GABA and CaCl 2 improved the antioxidant activity and postharvest quality of cut roses by reducing PPO activity and MDA contents, increasing protein content and prolonging vase life. This treatment is a potential postharvest strategy to improve antioxidant capacity and delay senescence in cut roses., (© 2024. The Author(s).)

Roses are among the most popular ornamental plants cultivated worldwide for their great economic, symbolic, and cultural importance. Nevertheless, rapid petal senescence markedly reduces rose (Rosa hybrida) flower quality and value. Petal senescence is a developmental process tightly regulated by various phytohormones. Ethylene accelerates petal senescence, while gibberellic acid (GA) delays this process. However, the molecular mechanisms underlying the crosstalk between these phytohormones in the regulation of petal senescence remain largely unclear. Here, we identified SENESCENCE-ASSOCIATED F-BOX (RhSAF), an ethylene-induced F-box protein gene encoding a recognition subunit of the SCF-type E3 ligase. We demonstrated that RhSAF promotes degradation of the GA receptor GIBBERELLIN INSENSITIVE DWARF1 (RhGID1) to accelerate petal senescence. Silencing RhSAF expression delays petal senescence, while suppressing RhGID1 expression accelerates petal senescence. RhSAF physically interacts with RhGID1s and targets them for ubiquitin/26S proteasome-mediated degradation. Accordingly, ethylene-induced RhGID1C degradation and RhDELLA3 accumulation are compromised in RhSAF-RNAi lines. Our results demonstrate that ethylene antagonizes GA activity through RhGID1 degradation mediated by the E3 ligase RhSAF. These findings enhance our understanding of the phytohormone crosstalk regulating petal senescence and provide insights for improving flower longevity., Competing Interests: Conflict of interest statement. The authors declare no competing interests., (© The Author(s) 2024. Published by Oxford University Press on behalf of American Society of Plant Biologists. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Roses are widely used as cut flowers worldwide. Petal senescence confines the decorative quality of cut rose flowers, an impressively considerable economic loss. Herein, we investigated the SUMO1/SUMO E3 ligase SIZ1 signaling pathway during bud opening, and petal senescence of cut rose flowers. Our results exhibited that the higher expression of SUMO1 and SUMO E3 ligase SIZ1 during bud opening was accompanied by lower endogenous H 2 O 2 accumulation arising from higher expression and activities of SOD, CAT, APX, and GR, promoting proline accumulation by increasing P5CS expression and activity and enhancing GABA accumulation by increasing GAD expression and activity. In harvested flowers, lower expressions of SUMO1 and SUMO E3 ligase SIZ1 during petal senescence were associated with higher endogenous H 2 O 2 accumulation due to lower expression and activities of SOD, CAT, APX, and GR. Therefore, promoting the activity of the GABA shunt pathway as realized by higher expression and activities of GABA-T and SSADH accompanied by increasing OAT expression and activity for sufficiently supply proline in rose flowers during petal senescence might serve as an endogenous antisenescence mechanism for slowing down petals senescence by avoiding endogenous H 2 O 2 accumulation. Following phytosulfokine α (PSKα) application, postponing petal senescence in cut rose flowers could be ascribed to higher expression of SUMO1 and SUMO E3 ligase SIZ1 accompanied by higher expression and activities of SOD, CAT, APX, and GR, higher activity of GABA shunt pathway as realized by higher expression and activities of GAD, GABA-T, and SSADH, higher expression and activities of P5CS and OAT for supplying proline and higher expression of HSP70 and HSP90. Therefore, our results highlight the potential of the PSKα as a promising antisenescence signaling peptide in the floriculture industry for postponing senescence and extending the vase life of cut rose flowers., (© 2021. The Author(s).)

Flowers are the core reproductive structures and key distinguishing features of angiosperms. Flower opening to expose stamens and gynoecia is important in cases where pollinators much be attracted to promote cross-pollination, which can enhance reproductive success and species preservation. The floral opening process is accompanied by the coordinated movement of various floral organs, particularly petals. However, the mechanisms underlying petal movement and flower opening are not well understood. Here, we integrated anatomical, physiological, and molecular approaches to determine the petal movement regulatory network using rose (Rosa hybrida) as a model. We found that PETAL MOVEMENT-RELATED PROTEIN1 (RhPMP1), a homeodomain transcription factor (TF) gene, is a direct target of ETHYLENE INSENSITIVE3, a TF that functions downstream of ethylene signaling. RhPMP1 expression was upregulated by ethylene and specifically activated endoreduplication of parenchyma cells on the adaxial side of the petal (ADSP) base by inducing the expression of RhAPC3b, a gene encoding the core subunit of the Anaphase-Promoting Complex. Cell expansion of the parenchyma on the ADSP base was subsequently enhanced, thus resulting in asymmetric growth of the petal base, leading to the typical epinastic movement of petals and flower opening. These findings provide insights into the pathway regulating petal movement and associated flower-opening mechanisms.�., (� The Author(s) 2021. Published by Oxford University Press on behalf of American Society of Plant Biologists.)

Developmental transitions in plants require adequate carbon resources, and organ abscission often occurs due to competition for carbohydrates/assimilates. Physiological studies have indicated that organ abscission may be activated by Suc deprivation; however, an underlying regulatory mechanism that links Suc transport to organ shedding has yet to be identified. Here, we report that transport of Suc and the phytohormone auxin to petals through the phloem of the abscission zone (AZ) decreases during petal abscission in rose ( Rosa hybrida ), and that auxin regulates Suc transport into the petals. Expression of the Suc transporter Rh SUC2 decreased in the AZ during rose petal abscission. Similarly, silencing of Rh SUC2 reduced the Suc content in the petals and promotes petal abscission. We established that the auxin signaling protein Rh ARF7 binds to the promoter of Rh SUC2 , and that silencing of Rh ARF7 reduces petal Suc contents and promotes petal abscission. Overexpression of Rh SUC2 in the petal AZ restored accelerated petal abscission caused by Rh ARF7 silencing. Moreover, treatment of rose petals with auxin and Suc delayed ethylene-induced abscission, whereas silencing of Rh ARF7 and Rh SUC2 accelerated ethylene-induced petal abscission. Our results demonstrate that auxin modulates Suc transport during petal abscission, and that this process is regulated by a Rh ARF7- Rh SUC2 module in the AZ., (© 2020 American Society of Plant Biologists. All rights reserved.)

Key Message: H 2 prolonged the vase life and improved the vase quality of cut roses through repressing endogenous ethylene production and alleviating ethylene signal transduction during the entire senescing period. Recently, the application of hydrogen gas (H 2 ) was shown to improve postharvest quality and longevity in perishable horticultural products, but the specific regulation mechanism remains obscure. Here, endogenous ethylene production and the expression of genes in ethylene biosynthesis and signalling pathway were investigated to explore the crosstalk between H 2 and ethylene during the senescence of cut roses. Our results revealed that addition of exogenous ethylene by ethephon accelerated the senescence of cut roses, in which 100 mg L -1 ethephon displayed the most obvious senescent phenotype. While the applied different concentrations (1%, 10%, 50% and 100%) of hydrogen-rich water (HRW) conducted different affects in alleviating the senescence of cut roses, and 1% HRW displayed the best ornamental quality and the longest vase life by reducing ethylene production, supported by the decrease of 1-aminocyclopropene-1-carboxylate (ACC) accumulation, ACC synthase (ACS) and ACC oxidase (ACO) activities, and Rh-ACS3 and Rh-ACO1 expressions in ethylene biosynthesis. In addition, HRW increased the transcripts of ethylene receptor genes Rh-ETR1 at blooming period from day 4 to day 6 and suppressed Rh-ETR3 at senescence phase at day 8 after harvest. Furthermore, the relevant affection of HRW on Rh-ETR1 and Rh-ETR3 expressions still existed when the ethylene production was compromised by adequate addition of exogenous ethylene in HRW-treated cut rose petals, and HRW directly repressed the protein level of Rh-ETR3 in a transient expression assay. Overall, the results suggested that H 2 is involved in neutralizing ethylene-mediated postharvest in cut flowers.

Apical dominance occurs when the growing shoot tip inhibits the outgrowth of axillary buds. Apically-derived auxin in the nodal stem indirectly inhibits bud outgrowth via cytokinins and strigolactones. Recently, sugar deprivation was found to contribute to this phenomenon. Using rose and pea, we investigated whether sugar availability interacts with auxin in bud outgrowth control, and the role of cytokinins and strigolactones, in vitro and in planta. We show that sucrose antagonises auxin's effect on bud outgrowth, in a dose-dependent and coupled manner. Sucrose also suppresses strigolactone inhibition of outgrowth and the rms3 strigolactone-perception mutant is less affected by reducing sucrose supply. However, sucrose does not interfere with the regulation of cytokinin levels by auxin and stimulates outgrowth even with optimal cytokinin supply. These observations were assembled into a computational model in which sucrose represses bud response to strigolactones, largely independently of cytokinin levels. It quantitatively captures our observed dose-dependent sucrose-hormones effects on bud outgrowth and allows us to express outgrowth response to various combinations of auxin and sucrose levels as a simple quantitative law. This study places sugars in the bud outgrowth regulatory network and paves the way for a better understanding of branching plasticity in response to environmental and genotypic factors., (© 2019 INRAE New Phytologist © 2019 New Phytologist Trust.)

The effect of foliar application of polyamines on roses (Rosa hybrida cv. 'Herbert Stevens') was investigated in a factorial experiment based on a completely randomized design with three replications in a greenhouse. Two factors were applied including polyamine type (putrescine, spermidine, and spermine) and polyamine concentration (0, 1, 2 and 4 mM). The recorded traits included root fresh and dry weight, root length, number of flowers, flower longevity, chlorophyll content, carotenoids, antioxidant enzymes activity (catalase, ascorbate peroxidase and guaiacol peroxidase) and some macronutrients such as nitrogen, phosphorus and potassium. The results showed that among polyamines, putrescine had the greatest effect on root dry weight; spermidine showed the greatest effect on root length, chlorophyll content, plant phosphorus and spermine affected root fresh weight and flower longevity most strongly. Polyamine concentration of 1 mM had the strongest effect on flower longevity, carotenoids, nitrogen and phosphorus content. The highest potassium rate was observed in treatments with the concentration of 4 mM. Polyamine treatments had no significant effect on the number of flowers per plant and antioxidant enzymes.

In rose (Rosa hybrida), flower senescence is accelerated by ethylene and delayed by cytokinins (CTKs). However, the effectors that regulate these processes are not currently understood. In this study, we identified an APETALA2/ethylene-responsive factor (AP2/ERF) gene, RhERF113, which was induced by ethylene and up-regulated during flower senescence in most floral organs, including sepal, petal, stamen and pistil. The virus-induced gene silencing (VIGS) of RhERF113 expression accelerated rose flower senescence, which was accompanied by a lower CTK content in the flowers. This accelerated senescence could be restored by exogenous CTK treatment. Moreover, the expression levels of genes related to CTK biosynthesis and signaling, including ISOPENTENYL TRANSFERASE 5 (RhIPT5), RhIPT8, HISTIDINE KINASE 2 (RhHK2), RhHK3, CYTOKININ RESPONSE REGULATOR 3 (RhCRR3), RhCRR5, RhCRR8, HOMEOBOX PROTEIN 6 (RhHB6) and PATHOGENESIS-RELATED 10.1 (RhPR10.1), were decreased in the RhERF113-silenced rose flowers. Taken together, our results demonstrate that RhERF113 delays ethylene-induced flower senescence by increasing the CTK content of the floral tissues.

Wastewater is an alternative to traditional sources of renewable irrigation water in agriculture, particularly in water-scarce regions. However, the possible risks due to heavy metals accumulation in plant tissues are often overlooked by producers. The present study aimed to identify heavy metals-induced structural modifications to roots of scented Rosa species that were irrigated with water of marginal quality. The chemical and mineral contents from the experimental irrigation canal water (control) and treated wastewater were below the limits recommended by the Pakistan Environmental Protection Agency (Pak-EPA) for medicinal plants. The experimentally untreated wastewater contained electrical conductivity (EC), chemical oxygen demand (COD), biological oxygen demand (BOD), and heavy metals (Co, Cu, Cd, Pb) that were above the recommended limits. The responses by wastewater-treated Rosa species (Rosa damascena, R. bourboniana, R. Gruss-an-Teplitz, and R. centifolia) were evaluated. The experimental data revealed that treated wastewater significantly increased the thickness of collenchyma (cortex and pith) and parenchyma tissues (vascular bundle, xylem, and phloem) of R. Gruss-an-Teplitz. Root dermal tissues (epidermis) of R. bourboniana also responded to treated wastewater. R. damascena and R. centifolia were the least affected species, under the experimental irrigation conditions. Collenchyma and dermal tissues were thicker in R. damascena and R. Gruss-an-Teplitz under untreated wastewater conditions. In parenchyma tissues, vascular bundles were thicker in R. damascena in untreated wastewater conditions, while the xylem and phloem of R. Gruss-an-Teplitz were thicker where treated wastewater was applied. In tissues other than the vascular bundle, the differences in anatomical metrics due to the experimental irrigation treatments were greater during the second year of the experiment than in the first year. The contents of metals other than chromium in the roots and stems of roses were below the WHO limits, under all of the experimental irrigation conditions. Rosa centifolia contained higher heavy metals content than the other experimental species, and heavy metals content was associated with anatomical changes due to the treatments. We conclude that, under conditions of wastewater irrigation, R. Gruss-an-Teplitz was highly resistant; R. damascena was moderately resistant while R. bourboniana and R. centifolia were the most susceptible to irrigation with marginal quality water. This is the first report of plant tissue responses to wastewater irrigation by the experimental species. Regarding the accumulation of heavy metals in rose plant tissues, the results confirm that untreated wastewater must be treated to grow Rosa species where water is scarce., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Plants regulate responses to salt stress using biological pathways, such as signal perception and transduction, photosynthesis, and energy metabolism. Little is known about the genetics of salt tolerance in Rosa chinensis. Tineke and Hiogi are salt-tolerant and salt-sensitive varieties of R. chinensis, respectively, and are good choices for studying salt-tolerance genes. We studied leaf and root tissues from 1-year-old Hiogi and Tineke plants simultaneously grown under the same conditions. A 0.4%-mmol/L salt ion mixture was added to the basic growth medium. Illumina sequencing was used to identify differentially expressed transcripts. GO and KEGG pathway enrichment analyses were performed to identify differentially expressed genes. We identified many differentially expressed genes associated with salt tolerance. The abscisic acid-dependent signaling pathway was the main pathway that mediated the salt stress response in R. chinensis. Two pathways (plant hormone signal transduction and glutathione metabolism) were also active in salt stress responses in R. chinensis. The difference in salt tolerance in the cultivars was due to different gene sensitivity to salt in these two pathways. Roots also play a role in salt stress response. The effects of salt stress in the roots are eventually manifested in the leaves, causing changes in processes such as photosynthesis, which eventually result in leaf wilting. In Tineke, Snrk2, ABF, HSP, GSTs, and GSH1 showed high activity during salt stress, indicating that these genes are markers of salt tolerance., Competing Interests: The authors have declared that no competing interests exist.

The current study was designed with the aim to investigate anti-anxiety potential of Hibiscus rosa sinensis roots and its possible mechanism of action. For this purpose hole board test, elevated plus maze test and light/dark exploration test were employed. The ethanol extract of plant was administered orally at two different doses i.e. 100 and 500 mg/kg for consecutive 14 days. The results of present investigation indicate that plant extract significantly (p < 0.05) increased the number of head dips and rearings as compared to control on respective days of observation. The extract increased the time of permanence in open arms and the number of head dips in elevated plus maze. In light/dark test, our study indicate that Hibiscus rosa sinensis significantly (p < 0.05) increased the time spent in light compartment and number of entries as compared to control. In addition the anxiolytic effects of HRS at highest tested dose were blocked by flumazenil, a GABA-A receptor antagonist that indicate that Hibiscus rosa sinensis potentiated the GABAergic actions. The results propose that the ethanol extract of Hibiscus rosa sinensis has prospective anxiolytic effect in mice via inhibition of ionotropic GABA receptors, using different behavioral paradigms.

Beneficial effects of silicon (Si) on growth and development have been witnessed in several plants. Nevertheless, studies on roses are merely reported. Therefore, the present investigation was carried out to illustrate the impact of Si on photosynthesis, antioxidant defense and leaf proteome of rose under salinity stress. In vitro-grown, acclimatized Rosa hybrida 'Rock Fire' were hydroponically treated with four treatments, such as control, Si (1.8 mM), NaCl (50 mM), and Si+NaCl. After 15 days, the consequences of salinity stress and the response of Si addition were analyzed. Scorching of leaf edges and stomatal damages occurred due to salt stress was ameliorated under Si supplementation. Similarly, reduction of gas exchange, photosynthetic pigments, higher lipid peroxidation rate, and accumulation of reactive oxygen species under salinity stress were mitigated in Si treatment. Lesser oxidative stress observed was correlated with the enhanced activity and expression of antioxidant enzymes, such as superoxide dismutase, catalase, and ascorbate peroxidase in Si+NaCl treatment. Importantly, sodium transportation was synergistically restricted with the stimulated counter-uptake of potassium in Si+NaCl treatment. Furthermore, two-dimensional electrophoresis (2-DE) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) results showed that out of 40 identified proteins, on comparison with control 34 proteins were down-accumulated and six proteins were up-accumulated due to salinity stress. Meanwhile, addition of Si with NaCl treatment enhanced the abundance of 30 proteins and downregulated five proteins. Differentially-expressed proteins were functionally classified into six groups, such as photosynthesis (22%), carbohydrate/energy metabolism (20%), transcription/translation (20%), stress/redox homeostasis (12%), ion binding (13%), and ubiquitination (8%). Hence, the findings reported in this work could facilitate a deeper understanding on potential mechanism(s) adapted by rose due to the exogenous Si supplementation during the salinity stress., Competing Interests: The authors declare no conflict of interest.

Bud outgrowth is under the intricate control of environmental and endogenous factors. In a recent paper, 1 we demonstrated that light perceived by Rosa buds triggers cytokinins (CK) synthesis within 3 hours in the adjacent node followed by their transport to the bud. There, CK control expression of a set of major genes (strigolactones-, auxin-, sugar sink strength-, cells division and elongation-related genes) leading to bud outgrowth in light. Conversely, under dark condition, CK accumulation and transport to the bud are repressed and no bud outgrowth occurs. In this paper, we show that the 3 expansin genes RhEXPA1,2,3 are under the control of both light and CK during bud outgrowth. In silico analysis of promoter sequences highlights 2 regions enriched in light and CK cis-regulatory elements as well as a specific cis-element in pRhEXPA3, potentially responsible for the expression patterns observed in response to CK and light.

In many plant species, including rose (Rosa hybrida), flower senescence is promoted by the gaseous hormone ethylene and inhibited by the cytokinin (CTK) class of hormones. However, the molecular mechanisms underlying these antagonistic effects are not well understood. In this study, we characterized the association between a pathogenesis-related PR-10 family gene from rose (RhPR10.1) and the hormonal regulation of flower senescence. Quantitative reverse transcription PCR analysis showed that RhPR10.1 was expressed at high levels during senescence in different floral organs, including petal, sepal, receptacle, stamen, and pistil, and that expression was induced by ethylene treatment. Silencing of RhPR10.1 expression in rose plants by virus-induced gene silencing accelerated flower senescence, which was accompanied by a higher ion leakage rate in the petals, as well as increased expression of the senescence marker gene RhSAG12 CTK content and the expression of three CTK signaling pathway genes were reduced in RhPR10.1-silenced plants, and the accelerated rate of petal senescence that was apparent in the RhPR10.1-silenced plants was restored to normal levels by CTK treatment. Finally, RhHB6, a homeodomain-Leu zipper I transcription factor, was observed to bind to the RhPR10.1 promoter, and silencing of its expression also promoted flower senescence. Our results reveal an ethylene-induced RhHB6-RhPR10.1 regulatory module that functions as a brake of ethylene-promoted senescence through increasing the CTK content., (© 2017 American Society of Plant Biologists. All Rights Reserved.)

Anthocyanidin reductase (ANR) is a key enzyme involved in the biosynthesis of proanthocyanidins (PAs) and plays a role in the plant stress response. However, the mechanism by which ANR confers stress tolerance in plants is not understood. Here, we report the isolation of RrANR, the homologous gene from rose, and NtABF, an ABA-response related transcription factor gene from tobacco. These genes were characterized regarding their functions in stress responses through the use of transgenic, transcriptomic and physiological analyses. Over-expression of RrANR in tobacco resulted in an increased accumulation of both PAs and abscisic acid (ABA), and also enhanced stress tolerance. Transcriptomic analysis of these transgenic tobacco lines indicated that RrANR overexpression induced global transcriptomic changes, including these involved in oxidation/reduction, hormone response and secondary metabolism. Genes related to ABA biosynthesis and reactive oxygen species (ROS)-scavenging were up-regulated in RrANR transgenic lines, and these effects were phenocopied by the direct treatment of tobacco plants with PAs and ABA. Transcriptomic data from each of these treatments identified the upregulation of a putative NtABF. Furthermore, the up-regulation of NtABF in RrANR transformants or in PAs- and ABA-treated tobacco plants was associated with enhanced stress tolerance. Overexpression of NtABF in transgenic tobacco mimicked the effects of RrANR-transgenic plants with regard to the up-regulation of ROS-scavenging genes and an increase in oxidative tolerance. Taken together, our findings indicate that overexpression of RrANR results in an increase in plant tolerance to oxidative stress via increased scavenging of ROS and modulation of the ABA signaling pathway., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

Rapid resistance detection is necessary for the adaptive management of acaricide-resistant populations of Tetranychus urticae. Detection of phenotypic and genotypic resistance was conducted by employing residual contact vial bioassay (RCV) and quantitative sequencing (QS) methods, respectively. RCV was useful for detecting the acaricide resistance levels of T. urticae, particularly for on-site resistance detection; however, it was only applicable for rapid-acting acaricides (12 out of 19 tested acaricides). QS was effective for determining the frequencies of resistance alleles on a population basis, which corresponded to 12 nonsynonymous point mutations associated with target-site resistance to five types of acaricides [organophosphates (monocrotophos, pirimiphos-methyl, dimethoate and chlorpyrifos), pyrethroids (fenpropathrin and bifenthrin), abamectin, bifenazate and etoxazole]. Most field-collected mites exhibited high levels of multiple resistance, as determined by RCV and QS data, suggesting the seriousness of their current acaricide resistance status in rose cultivation areas in Korea. The correlation analyses revealed moderate to high levels of positive relationships between the resistance allele frequencies and the actual resistance levels in only five of the acaricides evaluated, which limits the general application of allele frequency as a direct indicator for estimating actual resistance levels. Nevertheless, the resistance allele frequency data alone allowed for the evaluation of the genetic resistance potential and background of test mite populations. The combined use of RCV and QS provides basic information on resistance levels, which is essential for choosing appropriate acaricides for the management of resistant T. urticae.

Small molecules (xenobiotics) that inhibit cell-wall-localised enzymes are valuable for elucidating the enzymes' biological roles. We applied a high-throughput fluorescent dot-blot screen to search for inhibitors of Petroselinum xyloglucan endotransglucosylase (XET) activity in vitro. Of 4216 xenobiotics tested, with cellulose-bound xyloglucan as donor-substrate, 18 inhibited XET activity and 18 promoted it (especially anthraquinones and flavonoids). No compounds promoted XET in quantitative assays with (cellulose-free) soluble xyloglucan as substrate, suggesting that promotion was dependent on enzyme-cellulose interactions. With cellulose-free xyloglucan as substrate, we found 22 XET-inhibitors - especially compounds that generate singlet oxygen ((1)O2) e.g., riboflavin (IC50 29 μM), retinoic acid, eosin (IC50 27 μM) and erythrosin (IC50 36 μM). The riboflavin effect was light-dependent, supporting (1)O2 involvement. Other inhibitors included tannins, sulphydryl reagents and triphenylmethanes. Some inhibitors (vulpinic acid and brilliant blue G) were relatively specific to XET, affecting only two or three, respectively, of nine other wall-enzyme activities tested; others [e.g. (-)-epigallocatechin gallate and riboflavin] were non-specific. In vivo, out of eight XET-inhibitors bioassayed, erythrosin (1 μM) inhibited cell expansion in Rosa and Zea cell-suspension cultures, and 40 μM mycophenolic acid and (-)-epigallocatechin gallate inhibited Zea culture growth. Our work showcases a general high-throughput strategy for discovering wall-enzyme inhibitors, some being plant growth inhibitors potentially valuable as physiological tools or herbicide leads., (Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Many different types of toxins are produced by the fungus, Alternaria alternata (Fr.) Keissler. Little is known, however, regarding the influence of these toxins on insects. In this study, we investigated the toxin-induced inhibitory effects of the toxin produced by A. alternata on the rose aphid, Macrosiphum rosivorum, when the toxin was applied to leaves of the rose, Rosa chinensis. The results demonstrated that the purified crude toxin was non-harmful to rose plants and rose aphids, but had an intensive inhibitory effect on the multiplication of aphids. The inhibitory index against rose aphids reached 87.99% when rose plants were sprayed with the toxin solution at a low concentration. Further results from bioassays with aphids and high performance liquid chromatography (HPLC) analyses demonstrated that tenuazonic acid (TeA) was one of the most important resistance-related active components in the crude toxin. The content of TeA was 0.1199% in the crude toxin under the HPLC method. Similar to the crude toxin, the inhibitory index of pure TeA reached 83.60% 15 d after the rose plants were sprayed with pure TeA solution at the lower concentration of 0.060 μg/ml, while the contents of residual TeA on the surface and in the inner portion of the rose plants were only 0.04 and 0.00 ng/g fresh weight of TeA-treated rose twigs, respectively, 7 d after the treatment. Our results show that TeA, an active component in the A. alternata toxin, can induce the indirect plant-mediated responses in rose plants to intensively enhance the plant's resistances against rose aphids, and the results are very helpful to understand the plant-mediated interaction between fungi and insects on their shared host plants.

Rose is an ornamental plant which contains one of the world's top cut flowers. Vase life of cut rose flower is short. Extracts of Mentha pulegium and 8-hydroxy quinoline sulphate (8-HQS) were used as two preservative solutions, aiming to extend the vase life of cut rose (Rosa hybrid L.) flowers. Rose flowers were treated with a vase solution containing the extract of M. pulegium, at concentrations of 0, 10, 20 and 30%, in combination with 8-HQS at concentrations of 0, 200, 400 and 600 mg l(-1). Longevity of cut roses flowers was determined on the basis of wilting and chlorophyll retention. Cut roses flowers were kept at room temperature (20 ± 2 degrees C) under normal day light and natural ventilation. The vase life of cut flowers studied was prolonged by all 8-HQS and extract treatments. The best concentration of 8-HQS and extractwere 400 mg l(-1) and 10%, respectively. Our results indicated that the flowers treated with the extract and 8-HQS had longer vase life, higher rate of solution uptake and lower SPAD value (total chlorophyll) compared to the control. Also, cut flowers treated with the extract and 8-HQS had least bacterial colonies. The greatest longevity of vase life by 11.20 and 10.25 days was related to 400 mg I(-1) 8-HQS and 10% of extract, respectively. These treatments improved cut vase life more than the control treatment. The maximum solution uptake (1.85 ml g(-1) f.wt.) and minimum SPAD value (2.19) were calculated in 30% extract along with 200 mg l(-1) 8-HQS, and 200 mg l(-1) 8-HQS, respectively. The lowest number of bacterial colonies (55.75) was obtained in treatment of 600 mg l(-1) 8-HQS. Flower quality of specimens treated with extract and 8-HQS was better than those of the control. The experiments were repeated three times with three replicates and a completely randomized design had been used. The present study concludes that it would be possible to use preservative solutions containing extract of M. pulegium L. and 8-HQS to extend vase life of cut rose (R. hybrida L.) flowers.

Rose (Rosa hybrida) is one of the most important ornamental plants worldwide; however, senescence of its petals terminates the ornamental value of the flower, resulting in major economic loss. It is known that the hormones abscisic acid (ABA) and ethylene promote petal senescence, while gibberellins (GAs) delay the process. However, the molecular mechanisms underlying the antagonistic effects amongst plant hormones during petal senescence are still unclear. Here we isolated RhHB1, a homeodomain-leucine zipper I transcription factor gene, from rose flowers. Quantitative RT-PCR and GUS reporter analyses showed that RhHB1 was strongly expressed in senescing petals, and its expression was induced by ABA or ethylene in petals. ABA or ethylene treatment clearly accelerated rose petal senescence, while application of the gibberellin GA3 delayed the process. However, silencing of RhHB1 delayed the ABA- or ethylene-mediated senescence, and resulted in higher petal anthocyanin levels and lower expression of RhSAG12. Moreover, treatment with paclobutrazol, an inhibitor of GA biosynthesis, repressed these delays. In addition, silencing of RhHB1 blocked the ABA- or ethylene-induced reduction in expression of the GA20 oxidase encoded by RhGA20ox1, a gene in the GA biosynthetic pathway. Furthermore, RhHB1 directly binds to the RhGA20ox1 promoter, and silencing of RhGA20ox1 promoted petal senescence. Eight senescence-related genes showed substantial differences in expression in petals after treatment with GA3 or paclobutrazol. These results suggest that RhHB1 mediates the antagonistic effect of GAs on ABA and ethylene during rose petal senescence, and that the promotion of petal senescence by ABA or ethylene operates through an RhHB1-RhGA20ox1 regulatory checkpoint., (© 2014 The Authors The Plant Journal © 2014 John Wiley & Sons Ltd.)

The cell-wall pectic domain rhamnogalacturonan-II (RG-II) is cross-linked via borate diester bridges, which influence the expansion, thickness and porosity of the wall. Previously, little was known about the mechanism or subcellular site of this cross-linking. Using polyacrylamide gel electrophoresis (PAGE) to separate monomeric from dimeric (boron-bridged) RG-II, we confirmed that Pb(2+) promotes H3 BO3 -dependent dimerisation in vitro. H3 BO3 concentrations as high as 50 mm did not prevent cross-linking. For in-vivo experiments, we successfully cultured 'Paul's Scarlet' rose (Rosa sp.) cells in boron-free medium: their wall-bound pectin contained monomeric RG-II domains but no detectable dimers. Thus pectins containing RG-II domains can be held in the wall other than via boron bridges. Re-addition of H3 BO3 to 3.3 μm triggered a gradual appearance of RG-II dimer over 24 h but without detectable loss of existing monomers, suggesting that only newly synthesised RG-II was amenable to boron bridging. In agreement with this, Rosa cultures whose polysaccharide biosynthetic machinery had been compromised (by carbon starvation, respiratory inhibitors, anaerobiosis, freezing or boiling) lost the ability to generate RG-II dimers. We conclude that RG-II normally becomes boron-bridged during synthesis or secretion but not post-secretion. Supporting this conclusion, exogenous [(3) H]RG-II was neither dimerised in the medium nor cross-linked to existing wall-associated RG-II domains when added to Rosa cultures. In conclusion, in cultured Rosa cells RG-II domains have a brief window of opportunity for boron-bridging intraprotoplasmically or during secretion, but secretion into the apoplast is a point of no return beyond which additional boron-bridging does not readily occur., (© 2013 The Authors The Plant Journal published by Society for Experimental Biology and John Wiley & Sons Ltd.)

Objective: To explore the optimal plant growth regulator and its suitable concentration for the cutting propagation of Rosa laevigata., Methods: The cuttings were dealt with 6 kinds of plant growth regulators (IAA,IBA, NAA, PP333, 2, 4-D and ABT) at different concentrations (100, 200 and 500 mg/L) for 50 seconds. After 30 days growth, by analysis of variance and multiple comparisons,the most suitable cutting propagation method for Rosa laevigata was found., Results: Under the same condition, different concentration of different kinds of plant growth regulators had different effects on cutting propagation of Rosa laevigata. Generally speaking,cuttings soaked with 200 mg/L PP333 for 50 seconds was the best,with the high multiple effectiveness index and average root number (12.42); Cuttings soaked with 200 mg/L IBA for 50 seconds also had significant effects, with the second high multiple effectiveness index and the highest survival rate (96.67%)., Conclusion: 200 mg/L PP333 can promote cutting propagation of Rosa laevigata best.

Cell expansion is crucial for plant growth. It is well known that the phytohormone ethylene functions in plant development as a key modulator of cell expansion. However, the role of ethylene in the regulation of this process remains unclear. In this study, 2,189 ethylene-responsive transcripts were identified in rose (Rosa hybrida) petals using transcriptome sequencing and microarray analysis. Among these transcripts, an NAC (for no apical meristem [NAM], Arabidopsis transcription activation factor [ATAF], and cup-shaped cotyledon [CUC])-domain transcription factor gene, RhNAC100, was rapidly and dramatically induced by ethylene in the petals. Interestingly, accumulation of the RhNAC100 transcript was modulated by ethylene via microRNA164-dependent posttranscriptional regulation. Overexpression of RhNAC100 in Arabidopsis (Arabidopsis thaliana) substantially reduced the petal size by repressing petal cell expansion. By contrast, silencing of RhNAC100 in rose petals using virus-induced gene silencing significantly increased petal size and promoted cell expansion in the petal abaxial subepidermis (P < 0.05). Expression analysis showed that 22 out of the 29 cell expansion-related genes tested exhibited changes in expression in RhNAC100-silenced rose petals. Moreover, of those genes, one cellulose synthase and two aquaporin genes (Rosa hybrida Cellulose Synthase2 and R. hybrida Plasma Membrane Intrinsic Protein1;1/2;1) were identified as targets of RhNAC100. Our results suggest that ethylene regulates cell expansion by fine-tuning the microRNA164/RhNAC100 module and also provide new insights into the function of NAC transcription factors.

MicroRNAs play an important role in plant development and plant responses to various biotic and abiotic stimuli. As one of the most important ornamental crops, rose (Rosa hybrida) possesses several specific morphological and physiological features, including recurrent flowering, highly divergent flower shapes, colors and volatiles. Ethylene plays an important role in regulating petal cell expansion during rose flower opening. Here, we report the population and expression profiles of miRNAs in rose petals during flower opening and in response to ethylene based on high throughput sequencing. We identified a total of 33 conserved miRNAs, as well as 47 putative novel miRNAs were identified from rose petals. The conserved and novel targets to those miRNAs were predicted using the rose floral transcriptome database. Expression profiling revealed that expression of 28 known (84.8% of known miRNAs) and 39 novel (83.0% of novel miRNAs) miRNAs was substantially changed in rose petals during the earlier opening period. We also found that 28 known and 22 novel miRNAs showed expression changes in response to ethylene treatment. Furthermore, we performed integrative analysis of expression profiles of miRNAs and their targets. We found that ethylene-caused expression changes of five miRNAs (miR156, miR164, miR166, miR5139 and rhy-miRC1) were inversely correlated to those of their seven target genes. These results indicate that these miRNA/target modules might be regulated by ethylene and were involved in ethylene-regulated petal growth.

KEY MESSAGE : The P ( SAG12 ) -ipt gene was transferred to miniature rose, as the first woody species, resulting in increased ethylene resistance due to specific up-regulation of the ipt gene under senescence promoting conditions. Transgenic plants of Rosa hybrida 'Linda' were obtained via transformation with Agrobacterium tumefaciens strain harboring the binary vector pSG529(+) containing the P( SAG12 )-ipt construct. A. tumefaciens strains AGL1, GV3850 and LBA4404 (containing P(35S)-INTGUS gene) were used for transformation of embryogenic callus, but transgenic shoots were obtained only when AGL1 was applied. The highest transformation frequency was 10 % and it was achieved when half MS medium was used for the dilution of overnight culture of Agrobacterium. Southern blot confirmed integration of 1-6 copies of the nptII gene into the rose genome in the tested lines. Four transgenic lines were obtained which were morphologically true-to-type and indistinguishable from Wt shoots while they were in in vitro cultures. Adventitious root induction was more difficult in transgenic shoots compared to the Wt shoots, however, one of the transgenic lines (line 6) was rooted and subsequently analyzed phenotypically. The ipt expression levels were determined in this line after exposure to exogenous ethylene (3.5 μl l(-1)) and/or darkness. Darkness resulted in twofold up-regulation of ipt expression, whereas darkness combined with ethylene caused eightfold up-regulation in line 6 compared to Wt plants. The transgenic line had significantly higher content of chlorophyll at the end of the treatment period compared to Wt plants.

Application of 3.6 mm silicon (Si+) to the rose (Rosa hybrida) cultivar Smart increased the concentration of antimicrobial phenolic acids and flavonoids in response to infection by rose powdery mildew (Podosphaera pannosa). Simultaneously, the expression of genes coding for key enzymes in the phenylpropanoid pathway (phenylalanine ammonia lyase, cinnamyl alcohol dehydrogenase, and chalcone synthase) was up-regulated. The increase in phenolic compounds correlated with a 46% reduction in disease severity compared with inoculated leaves without Si application (Si-). Furthermore, Si application without pathogen inoculation induced gene expression and primed the accumulation of several phenolics compared with the uninoculated Si- control. Chlorogenic acid was the phenolic acid detected in the highest concentration, with an increase of more than 80% in Si+ inoculated compared with Si- uninoculated plants. Among the quantified flavonoids, rutin and quercitrin were detected in the highest concentrations, and the rutin concentration increased more than 20-fold in Si+ inoculated compared with Si- uninoculated plants. Both rutin and chlorogenic acid had antimicrobial effects on P. pannosa, evidenced by reduced conidial germination and appressorium formation of the pathogen, both after spray application and infiltration into leaves. The application of rutin and chlorogenic acid reduced powdery mildew severity by 40% to 50%, and observation of an effect after leaf infiltration indicated that these two phenolics can be transported to the epidermal surface. In conclusion, we provide evidence that Si plays an active role in disease reduction in rose by inducing the production of antifungal phenolic metabolites as a response to powdery mildew infection.

Plants of several species, if grown at high relative air humidity (RH ≥85%), develop stomata that fail to close fully in case of low leaf water potential. We studied the effect of a reciprocal change in RH, at different stages of leaf expansion of Rosa hybrida grown at moderate (60%) or high (95%) RH, on the stomatal closing ability. This was assessed by measuring the leaf transpiration rate in response to desiccation once the leaves had fully expanded. For leaves that started expanding at high RH but completed their expansion after transfer to moderate RH, the earlier this switch took place the better the stomatal functioning. Leaves initially expanding at moderate RH and transferred to high RH exhibited poor stomatal functioning, even when this transfer occurred very late during leaf expansion. Applying a daily abscisic acid (ABA) solution to the leaves of plants grown at continuous high RH was effective in inducing stomatal closure at low water potential, if done before full leaf expansion (FLE). After FLE, stomatal functioning was no longer affected either by the RH or ABA level. The results indicate that the degree of stomatal adaptation depends on both the timing and duration of exposure to high RH. It is concluded that stomatal functionality is strongly dependent on the humidity at which the leaf completed its expansion. The data also show that the effect of ambient RH and the alleviating role of ABA are restricted to the period of leaf expansion., (Copyright © Physiologia Plantarum 2011.)

Summary: *Apoplastic ascorbate has been proposed to confer resistance to oxidative stresses, e.g. ozone. We investigated reactive oxygen species (ROS)-induced secretion and catabolism of ascorbate. *Late-growth-phase cultured cells of rose and Arabidopsis were preloaded with [(14)C]ascorbate. Radiolabelled metabolites and secretion products were analysed by high-voltage electrophoresis. *In both species, exogenous 1 mM hydrogen peroxide (H(2)O(2)) rapidly stimulated [(14)C]ascorbate and [(14)C]dehydroascorbate accumulation in the medium (apoplast). Net (14)C export was most rapid within 100 s of washing, and often showed superimposed pulses, of c. 10-s duration, whose amplitude was greater after H(2)O(2) treatment. Oxidative stress did not cause indiscriminate metabolite leakage from the cells. H(2)O(2) caused c. 20-40% of the intracellular [(14)C]ascorbate to be irreversibly catabolized to [(14)C]oxalyl-threonate and related products; however, the great majority of the extracellular radioactivity remained as [(14)C]ascorbate and [(14)C]dehydroascorbate. Much of the apoplastic dehydroascorbate was probably reabsorbed by the cells and reduced back to ascorbate. *The data show that exported ascorbate can serve an apoplastic antioxidant role in these late-growth-phase cells without being irreversibly lost, whereas in early-growth-phase cells most extracellular ascorbate is irreversibly degraded. In conclusion, cultured plant cells can respond actively to oxidative stress by reversibly exporting ascorbate into the apoplast.

A new protocol for plant regeneration via protocorm-like bodies (PLBs) induced from rhizoids that developed from leaf explants of Rosa spp. (R. canina L., R. multiflora var. cathayensis Rehd. et Wils., and R. multiflora f. carnea Thory.) has been established. Rhizoids were induced from calli of leaf explants incubated under dark conditions on Murashige and Skoog (MS) medium containing 1.5 mg/l 2, 4-D. PLBs developed from the tip of rhizoids cultured under light conditions on (1/2) MS medium containing 20 mg/l TDZ. About 90, 17 and 93% of rhizoid formation were achieved for the above-mentioned Rosa spp., respectively using this protocol. The frequency of PLB clusters formation and the number of PLB clusters per explant reached 50% and 5.1 for R. canina, 46.7% and 0.8 for R. multifolra var. cathayensis, 46.7% and 4.2 for R. multiflora f. carnea, respectively. PLB clusters regenerated on MS medium supplemented with 2 mg/l 6-BA, 0.1 mg/l IBA, and 0.1 mg/l GA(3). The best result of regenerated plantlets per leaf explant achieved via PLBs for the three Rosa spp. mentioned above was 3.6, 0.1, and 1.2, respectively. Environmental scanning electron microscope and histological studies revealed that rhizoids were structurally different from roots grown in vitro, and PLBs developed from proembryos.

Ethylene production, as well as the expression of ethylene biosynthetic (Rh-ACS1-4 and Rh-ACO1) and receptor (Rh-ETR1-5) genes, was determined in five different floral tissues (sepals, petals, stamens, gynoecia, and receptacles) of cut rose (Rosa hybrida cv. Samantha upon treatment with ethylene or the ethylene inhibitor 1-methylcyclopropene (1-MCP). Ethylene-enhanced ethylene production occurred only in gynoecia, petals, and receptacles, with gynoecia showing the greatest enhancement in the early stage of ethylene treatment. However, 1-MCP did not suppress ethylene production in these three tissues. In sepals, ethylene production was highly decreased by ethylene treatment, and increased dramatically by 1-MCP. Ethylene production in stamens remained unchanged after ethylene or 1-MCP treatment. Induction of certain ethylene biosynthetic genes by ethylene in different floral tissues was positively correlated with the ethylene production, and this induction was also not suppressed by 1-MCP. The expression of Rh-ACS2 and Rh-ACS3 was quickly induced by ethylene in gynoecia, but neither Rh-ACS1 nor Rh-ACS4 was induced by ethylene in any of the five tissues. In addition, Rh-ACO1 was induced by ethylene in all floral tissues except sepals. The induced expression of ethylene receptor genes by ethylene was much faster in gynoecia than in petals, and the expression of Rh-ETR3 was strongly suppressed by 1-MCP in all floral tissues. These results indicate that ethylene biosynthesis in gynoecia is regulated developmentally, rather than autocatalytically. The response of rose flowers to ethylene occurs initially in gynoecia, and ethylene may regulate flower opening mainly through the Rh-ETR3 gene in gynoecia.

An experiment was conducted to evaluate the performance of various levels of indole-3-acetic acid (IAA) and naphthalene acetic acid (NAA) treatments i.e., 0, 25, 50, 75, 100 mg L(-1) on the regeneration of damask rose (Rosa damascena Mill.) cuttings in different growing media at the research farm of Arid Zone Research Institute D.I. Khan during 2004. The data revealed significant effect of different levels of growth regulators and growing media on the rose establishment parameters viz., plant height, plant spread, number of primary shoots, secondary shoots and survival percentage. Maximum plant height (134.2 cm), plant spread (46.3 cm), primary shoots (6.3), secondary shoots (25) and survival percentage (94.72%) were recorded when the rose cuttings were applied with NAA at the rate of 50 mg L(-1). Among the plant growth regulators, Naphthalene Acetic Acid (NAA) was found to be superior to indole-3-acetic acid (IAA) for its stronger effect regarding all parameters. The optimum level of Naphthalene Acetic Acid (NAA) was found in the range of 50 and 75 mg L(-1), while no such conclusion could be drawn for indole-3-acetic acid (IAA) as all growth parameters were linearly increased up to the highest concentrations of IAA i.e., 100 mg L(-1). Regarding growing media, the leaf mould appeared the best in terms of its positive effect on establishment of rose cuttings by giving the maximum plant height (125.1 cm), plant spread (37 cm), primary shoots (5.2), secondary shoots (19.48) and survival percentage (85.67%), followed by soil + leaf mould, while soil media was least effective.

In many states, Japanese beetle, Popilliajaponica Newman (Coleoptera: Scarabeidae), is no longer quarantined, and management is left to professional applicators and consumers. Adult management in hybrid tea rose, Rosa L., was compared among biorational insecticides, novel imidacloprid applications (tablet, gel, and root dip), and conventional insecticides. Efficacy of biorational insecticides used by consumers varied widely and may not offer predictable management: mortality was 3.0% with Garlic Barrier, 5.0% with Monterey Neem Oil, 15.1% with Pygenic (1.4% pyrethrins), and 27.3% with Orange Guard (D-limonene). Only JB Killer (0.02% pyrethrins plus 0.2% piperonyl butoxide) had mortality of 90.9%, probably due to piperonyl butoxide. Professional biorationals did not show significant mortality: 7.7% with Azatin XL (azadirachtin) and 3.7% Conserve (spinosad). In contrast, conventional insecticides demonstrated significant mortality; 88.4% with Decathlon 20 WP (cyfluthrin) and 83.3% with Discus SC (imidacloprid plus cyfluthrin). New imidacloprid applications (tablet, gel, and root dip) worked as well as standard drench and granular methods, but they showed 9.1-42.7% mortality. However, beetles were incapacitated as demonstrated by inability to walk (82-106-s flip time) compared with controls (30-s flip time). No phytotoxicity was observed in any treatments. However, some imidacloprid treatments produced growth enhancement: higher leaf chlorophyll (1X, 3X granular, and one tablet), and larger leaf area and higher nitrogen (3X granular, drench). The highest (active ingredient) imidacloprid was in 3X granular treatment, which in an unplanned infestation, showed highest numbers of twospotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae). Effects of imidacloprid on leaf quality and mite outbreaks deserves research.

In this work, the effect of ethylene on flower opening of cut rose (Rosa hybrida) cv. Samantha was studied. However, although ethylene hastened the process of flower opening, 1-MCP (1-methylcyclopropene), an ethylene action inhibitor, impeded it. Ethylene promoted ethylene production in petals, but 1-MCP did not inhibit this process. Of the four ethylene biosynthetic genes tested, Rh-ACS1 and Rh-ACS2 were undetectable; Rh-ACS3 and Rh-ACO1 expression was enhanced by ethylene slightly and greatly, respectively. However, their mRNA amounts were not inhibited by 1-MCP compared with controls. Expression of seven signalling component genes was also studied, including three ethylene receptors (Rh-ETR1, Rh-ETR3, and Rh-ETR5), two CTRs (Rh-CTR1 and Rh-CTR2), and two transcription factors (Rh-EIN3-1 and Rh-EIN3-2). Transcripts of Rh-ETR5, Rh-EIN3-1, and Rh-EIN3-2 were accumulated in a constitutive manner and had no or little response to ethylene or 1-MCP, while transcript levels of Rh-ETR1 and Rh-CTR1 were substantially elevated by ethylene, and those of Rh-ETR3 and Rh-CTR2 were greatly enhanced by ethylene; 1-MCP reduced all the four genes to levels much less than those in control flowers. These results show that ethylene triggers physiological responses related to flower opening in cut rose cv. Samantha, and that continued ethylene perception results in flower opening. Ethylene may regulate flower opening mainly through expression of two ethylene receptor genes (Rh-ETR1 and Rh-ETR3) and two CTR (Rh-CTR1 and Rh-CTR2) genes.

Oxaziclomefone [OAC; IUPAC name 3-(1-(3,5-dichlorophenyl)-1-methylethyl)-3,4-dihydro-6-methyl-5-phenyl-2H-1,3-oxazin-4-one] is a new herbicide that inhibits cell expansion in grass roots. Its effects on cell cultures and mode of action were unknown. In principle, cell expansion could be inhibited by a decrease in either turgor pressure or wall extensibility. Cell expansion was estimated as settled cell volume; cell division was estimated by cell counting. Membrane permeability to water was measured by a novel method involving simultaneous assay of the efflux of (3)H(2)O and [(14)C]mannitol from a 'bed' of cultured cells. Osmotic potential was measured by depression of freezing point. OAC inhibited cell expansion in cultures of maize (Zea mays), spinach (Spinacia oleracea) and rose (Rosa sp.), with an ID(50) of 5, 30 and 250 nm, respectively. In maize cultures, OAC did not affect cell division for the first 40 h. It did not affect the osmotic potential of cell sap or culture medium, nor did it impede water transport across cell membranes. It did not affect cells' ability to acidify the apoplast (medium), which may be necessary for 'acid growth'. As OAC did not diminish turgor pressure, its ability to inhibit cell expansion must depend on changes in wall extensibility. It could be a valuable tool for studies on cell expansion.

The purpose of this paper is to investigate the differential responses of flower opening to ethylene in two cut rose cultivars, 'Samantha', whose opening process is promoted, and 'Kardinal', whose opening process is inhibited by ethylene. Ethylene production and 1-aminocyclopropane-1-carboxylate (ACC) synthase and oxidase activities were determined first. After ethylene treatment, ethylene production, ACC synthase (ACS) and ACC oxidase (ACO) activities in petals increased and peaked at the earlier stage (stage 3) in 'Samantha', and they were much more dramatically enhanced and peaked at the later stage (stage 4) in 'Kardinal' than control during vasing. cDNA fragments of three Rh-ACSs and one Rh-ACO genes were cloned and designated as Rh-ACS1, Rh-ACS2, Rh-ACS3 and Rh-ACO1 respectively. Northern blotting analysis revealed that, among three genes of ACS, ethylene-in- duced expression patterns of Rh-ACS3 gene corresponded to ACS activity and ethylene production in both cultivars. A more dramatic accumulation of Rh-ACS3 mRNA was induced by ethylene in 'Kardinal' than that of 'Samantha'. As an ethylene action inhibitor, STS at concentration of 0.2 mmol/L generally inhibited the expression of Rh-ACSs and Rh-ACO in both cultivars, although it induced the expression of Rh-ACS3 transiently in 'Kardinal'. Our results suggests that 'Kardinal' is more sensitive to ethylene than 'Samantha'; and the changes of Rh-ACS3 expression caused by ethylene might be related to the acceleration of flower opening in 'Samantha' and the inhibition in 'Kardinal'. Additional results indicated that three Rh-ACSs genes were differentially associated with flower opening and senescence as well as wounding

Shoot tips of the diploid rose Thérèse Bugnet were treated in vitro to oryzalin at concentrations of 5 and 15 microM. Tetraploid shoots were obtained in highest frequencies (40%) after exposure to 5 microM oryzalin for 14 days. Thin (1 mm) nodal sections were treated with 5 microM oryzalin and the highest frequency of tetraploids (66%) was obtained after exposure for only 1 day. The shorter exposure times required to induce chromosome doubling in thin nodal sections is attributed to the more efficient delivery of oryzalin to the meristem. Tetraploids were obtained from four diploid roses and hexaploids from two triploid roses. Chromosome doubling was accompanied by increases in thickness and a darker green colouration of the leaves and, in all diploid to tetraploid and one triploid to hexaploid conversion, the breadth/length ratio of leaflets was significantly increased. Internodes were longer in tetraploids than diploids but significantly shorter in hexaploids than triploids. The number of petals per flower in the tetraploid form of Thérèse Bugnet was double that of the diploid. Significant increases in pollen viability accompanied chromosome doubling of all four diploids and one of the two triploids.

The efficacy and eventual phytotoxicity of oils from rape, sunflower seed (vegetable oil) and paraffin (Atpolan 80 EC) in the control of Sphaerotheca pannosa var. rosae were evaluated on roses grown in greenhouse or plastic tunnel. Oils were applied curativelly as plant spray 4-times at 7-day-intervals in concentrations from 0.25 to 4%. All used oils, gave as good effect as triforine (standard) or even better. On shrubs protected with oils at concentrations 0.25% and 0.5%, disease symptoms were noted only sporadically. Rose shrubs sprayed with higher concentration of oils were almost completely protected. Efficacy of tested oils increased with their concentrations. Paraffin oil was better in the control of S. pannosa var. rosae than vegetable oils. After 2 oil applications at conc. 2% or higher, first phytotoxicity symptoms on leaves were noted, particularly during warm and sunny days. Observations of treated leaves, 24 h after spraying under microscope, showed that all tested oils caused hyphae and spores degeneration or their visible deformation suggesting partial loss of turgidity. Depends on oil concentrations used, sporadically regular and unchanged shape hyphae and spores were visible.