Flower Senescence Research Articles

Application of 1-MCP as a liquid formulation prevents ethylene-induced senescence in Phalaenopsis orchid flowers and Kalanchoë blossfeldiana inflorescences

ABSTRACT This study provides a very first report on the use of a sprayable formulation of 1-MCP, HarvistaTM, on ornamental plant species. Individual florets of Phalaenopsis and inflorescences of Kalanchoë blossfeldiana were sprayed with 1, 2, 4, or 6% HarvistaTM and this was compared to the commonly used 1-MCP formulation, SmartFreshTM, which is administered as a powder releasing gas. HarvistaTM treatments for Kalanchoë were in addition also compared to plants treated with an alternative ethylene receptor blocker, STS, as well as with transgenic plants expressing the etr1-1 mutant gene of Arabidopsis thaliana. In the presence of ethylene, HarvistaTM at all concentrations (except 1% for Kalanchoë), as well as the conventional SmartFreshTM treatment, prevented wilting of florets and significantly extended their display life compared to that of control treatments: up to twofold for Kalanchoë and up to fourfold for Phalaenopsis. For Kalanchoë the best display life was, however, presented by etr1-1 transgenic plants. The efficacy and suitability of using HarvistaTM, a sprayable formulation of 1-MCP, was compared to using the gaseous application of SmartFreshTM, or the environmental hazardous silver treatment, against having to consider expensive and lengthy genetic modification with etr1-1 as commercial alternatives to achieve protection against the detrimental effects of ethylene. Abbreviations: 1-MCP, 1-methylcyclopropene; STS, silver thiosulfate

Seasonal dynamics of lingonberry and blueberry spectra

Accurate mapping of the spatial distribution of understory species from spectral images requires ground reference data which represent the prevailing phenological stage at the time of image acquisition. We measured the spectral bidirectional reflectance factors (BRFs, 350–2500 nm) at varying view angles for lingonberry ( L.) and blueberry ( L.) throughout the growing season of 2017 using Finnish Geospatial Research Institute’s FIGIFIGO field goniometer. Additionally, we measured spectra of leaves and berries of both species, and flowers of lingonberry. Both lingonberry and blueberry showed seasonality in visible and near-infrared spectral regions which was linked to occurrences of leaf growth, flowering, berrying, and leaf senescence. The seasonality of spectra differed between species due to different phenologies (evergreen vs. deciduous). Vegetation indices, normalized difference vegetation index (NDVI), moisture stress index (MSI), plant senescence reflectance index (PSRI), and red-edge inflection point (REIP2), showed characteristic seasonal trends. NDVI and PSRI were sensitive to the presence of flowers and berries of lingonberry, while with blueberry the effects were less evident. Off-nadir observations supported differentiating the dwarf shrub species from each other but showed little improvement for detection of flowers and berries. Lingonberry and blueberry can be identified by their spectral signatures if ground reference data are available over the entire growing season. The spectral data measured in this study are reposited in the publicly open SPECCHIO Spectral Information System.Vaccinium vitis-idaeaVaccinium myrtillus

The Effect of a Sugar-Containing Preservative on Senescence-Related Processes in Cut Clematis Flowers

Clematis is a new species grown as cut flower, whose vase life is variable and cultivar-depended. Little is known about senescence of its cut flowers and their response to flower preservatives. The aim of the study was to evaluate the effect of a preservative (standard preservative SP, 8-hydroxyquinoline citrate plus sucrose) or a biocide solution (8-HQC) on certain senescence-related processes in cut clematis flowers. Analyses were done immediately after harvest and at the end of the vase life when control flowers held in water were wilting. A possible relationship between senescence parameters and the vase life of clematis taxa was also sought. As in most cut flowers, the contents of reducing sugars and soluble proteins in clematis petals decreased during the vase life while the proteolytic activity, including that of the cysteine protease, increased and was accompanied by accumulation of free proline and ammonium. Cut flower longevity in cultivars under study was not associated with the initial levels of reducing sugars, soluble proteins or free proline. Neither was the initial proteolytic activity or its increase during vase life related to the vase life itself: cultivars having comparable life spans differed dramatically in the initial and final proteolytic activities. Both solutions containing 8-HQC significantly affected the senescence-related processes and flowers held in them had more soluble proteins and lower proteolytic activity (total, and that of the cysteine protease) than control flowers held in water. Approximately a twofold increase in reducing sugars was observed in flowers held in SP relative to those held in water or in 8-HQC while the accumulation of free proline and ammonium was limited in their petals. This suggests a regulating action of exogenous sugar in senescence of clematis flowers. However, the delay of senescence produced by the preservative was not always associated with a longer vase life in any given cultivar. Further studies are needed to elucidate the role of sugar in clematis flower senescence.

The involvement of NO in ABA-delayed the senescence of cut roses by maintaining water content and antioxidant enzymes activity

Abscisic acid (ABA) coordinates plant growth and development as internal signals. Nitric oxide (NO) as an essential endogenous signal molecule may prolong the vase life of cut flowers. However, the interaction of between ABA and NO during postharvest life of perishable horticultural products was not clear. Here, cut roses were used to investigate the interaction between NO and ABA during the senescence of cut flowers. The results showed that ABA increased the vase life and flower diameter of cut roses in a dose-dependent manner, with maximal biological responses at 0.5 μM. Sodium tungstate, an NO biosynthesis inhibitor, significantly suppressed the vase life and diameter enhanced by ABA, indicating that endogenous NO might be involved in ABA-regulated cut flower senescence. ABA and a NO donor sodium nitroprusside (SNP) effectively increased leaf relative water content and reduced the rate of water loss via inducing stomatal closure. ABA and NO treatments significantly increased the activity of superoxide dismutase, peroxidase and ascorbate peroxidase and the content of leaf chlorophyll. Sodium tungstate also prevented the effects of ABA mentioned above. Altogether, NO may play a crucial role in ABA-delayed the senescence of cut roses by retarding water loss, stimulating enzyme activity and maintaining leaf chlorophyll content.

Flowering profile and ethylene production of a new carnation subspecies 'Mini-tiara'

Ethylene is involved in the senescence of carnation flowers. It is synthesized abundantly after full opening of the flowers and accelerates wilting of petals, which results in withering of the flowers. We investigated the possible involvement of ethylene production in the loss of display value of cut flowers of ‘Mini-tiara’ carnation, a new subspecies derived from Dianthus caryophyllus L. by interspecific cross with wild-type Dianthus species (wild pinks). Flowers of ‘Mini-tiara’ carnation have a unique morphology with pointed-shaped petals, some of which in the middle part of the flowers stand straight and build a dome throughout the display time, and lose their display value when the dome collapses by bending all petals outside (full opening of flowers). Ethylene evolution from ‘Mini-tiara’ carnation was not detected from flowers with upstanding petals, but occurred several days after the collapse of the dome (after full opening of the flowers), the time they already lost their display value. These findings indicated that ethylene production is not engaged in the loss of display value of ‘Mini-tiara’ carnation.

Salicylic acid modulates cutting-induced physiological and biochemical responses to delay senescence in two gerbera cultivars

The postharvest longevity of gerbera (Gerbera jamesonii) flowers has a critical importance in determining their commercial value; and therefore, there is a commercial demand for prolonging their vase life (VL). Here, we tested the efficacy of salicylic acid (SA, 150 µM) preservative in extending longevity of cut flower of two gerbera cultivars, namely the ‘Sunway’ and ‘Bayadere’, of which water-held ‘Bayadere’ has longer VL than water-held ‘Sunway’. The results indicated that exogenous SA could significantly prolong the VL of cut flowers of both ‘Sunway’ and ‘Bayadere’ cultivars, with better preservative effect being observed on ‘Sunway’. SA preservative was more effective in ameliorating relative water uptake and relative fresh weight in ‘Sunway’ than in ‘Bayadere’, which was accompanied by a greater decrease in proline accumulation. Application of SA prolonged the VL of two cut gerbera flower cultivars by inhibiting the activity of polyphenol oxidase involved in browning reaction, and decreasing oxidative stress through improving reactive oxygen species-scavenging antioxidant capacity, which included accumulation of total phenolic compounds and total flavonoids, and enhancement of enzymatic antioxidant activities. As a result, membrane lipid peroxidation levels were reduced in cut flowers of both cultivars, with higher reduction level being observed in ‘Sunway’ than in ‘Bayadere’. Additionally, SA preservative was more efficient in maintaining a greater content of total soluble proteins in ‘Sunway’ than in ‘Bayadere’. These findings clearly demonstrated that SA has higher preservative effects on extending VL of ‘Sunway’ than that of ‘Bayadere’. Taken together, SA can be recommended to farmers for postharvest treatments to maintain quality and delay senescence of gerbera flowers.

Sensitivity of potted ornamental peppers to ethylene

Many environmental factors affect the post-production shelf life of potted ornamental plants. Exposure to ethylene can reduce the quality of many species, inducing flower, fruit and leaf abscission and senescence. The present study identified ethylene-resistant pepper genotypes during post-production shelf life testing. Potted plants of eleven pepper cultivars were transferred o a 90-L sealed container when they had 30% of ripe fruits and treated with 10 μL L-1 of ethylene for 48 hours. Number of leaves and fruits were counted at the beginning of ethylene exposure and after 48, 96 and 144 hours. The experimental design was completely randomized, with five replicates of individual pots. The cultivars showed varied rates of foliar and fruit abscission. ‘Peloteira’ showed higher resistance to ethylene, with foliar abscission of 19%, after 144 hours. For fruit abscission, the cultivars ‘Peloteira’, ‘Jalapeño’, ‘Stromboli ornamental’, ‘Malagueta’ and ‘Rocoto Vermelha’ presented a lower percentage of leaf drop, varying between 9 and 34%, after 144 hours of exposure to ethylene. This study showed that ornamental peppers have high genetic diversity regarding ethylene sensitivity.

Desenvolvimento de angelônia em vaso, sob doses de adubo de liberação lenta

Angelonia integerrima is a native species that has ornamental potential, being cultivated in flowerbeds, flowerpots, pots, or even used as a complement in floral arrangements. Knowledge of mineral nutrition is required for the cultivation of the species, and slow release fertilization have become widespread in recent years, with a lower risk of toxicity to crops, an economy in relation to complementary fertilizers and may be an alternative to cultivation of potted plants. The aim of this study was to evaluate the development of Angelonia integerrima Sprengel in pot under slow release fertilization doses. Acclimatized seedlings with approximately 1 cm height, from in vitro germinated seeds were transplanted into 1 L pots containing substrate composted Pinus bark. Five doses of Basacote ® 9M slow release fertilizer, formulation 16-8-12 (N - P2O5 - K2O), 9 months: control - 0 g L-1, 2.5 g L-1, 5.0 g L-1, 7.5 g L-1 and 10.0 g L-1. The plants were grown in a greenhouse under drip irrigation. The shoot length, length of the largest inflorescence, number of stems, diameter of the largest stem, mean length of the stems, number of open flowers, fruits and senescent flowers, chlorophyll a, b and total, mass of dry matter of shoot and root system were evaluated after 286 days. The experimental design was completely randomized, with four replicates of six pots per plot. Data were submitted to analysis of variance (ANOVA) followed by polynomial regression by SigmaPlot 11.0. It was possible to adjust a quadratic equation for the variables: shoot length (with maximum response point in 7.2 g L-1), mean length of stems (6.7 g L-1), diameter of the largest stem and the root system (5.9 g L-1), number of open flowers, buds, senescent flowers and total flowers (7.7 g L-1). For the variables, number of stems, number of fruits, chlorophyll a, b and total did not differ between treatments. The slow releaser fertilizer indicated dose for the cultivation of the potted species is 7.2 g L-1.

Endogenous hydrogen gas delays petal senescence and extends the vase life of lisianthus cut flowers

Exogenous hydrogen-rich water (HRW) improves vase life and quality of cut flowers, but the effects of endogenous hydrogen gas (H2) are not known. During the vase of cut lisianthus flowers, endogenous H2 concentrations decreased and redox homeostasis was impaired. The supplementation with HRW containing 0.078 mmol L−1 H2 blocked, but 2,6-dichlorophenolindophenol (DCPIP; a putative inhibitor of H2 synthesis) increased, endogenous H2 production. Senescence of cut flowers was delayed by H2, but accelerated by DCPIP. Also, decreased vase life by DCPIP was blocked by H2 administration. These beneficial roles of H2 were associated with less lipid peroxidation, and the increased activities of superoxide dismutase, ascorbate peroxidase, guaiacol peroxidase, and catalase. Compared with DCPIP alone, the soluble protein, total chlorophyll, and proline contents were elevated when H2 and DCPIP were added together. Overall, endogenous H2 prolongs vase life of lisianthus cut flowers in part by maintaining redox homeostasis.

Effects of pre-harvest applications of different source of calcium on the cell wall fractions and stem bending disorder of Gerbera (Gerbera jamesonii L.) cultivar flowers

Gerbera flower belongs to the composite family and is one of the top five cut flowers in the world in terms of production and consumption, which has a great economic value in the international flowering industry. This study was designed to evaluate whether calcium pre-harvest application, provided through 0, 0.5, 1 and 1.5% of calcium chloride (CaCl2) and calcium nitrate (CaNO3), could extend the day of stem bending of gerbera cut flower. In the present study, we used two gerbera cultivars ‘Intense’ and ‘Rosaline’ as resistant and sensitive to stem bending, respectively. For evaluation of associated traits with stem bending, the produced flowers were kept in a vase solution containing 200 mg/L hydroxyquinoline with temperature conditions of 20°C. The results showed that day of stem bending of flowers extended 9.62 and 10.37 days by application of 1% CaCl2 for ‘Rosaline’ and ‘Intense’ respectively. All treatments were effective in the increasing relative water content of flower due to increase water uptake. The results also revealed that the calcium pretreatment delayed flowers senescence and increased antioxidant enzyme activity. Application of calcium resulted in an increase in membrane stability index in the cut flowers of both cultivars, providing evidence for delay of senescence in calcium-treated cut flowers. Also, results showed that calcium application significantly increased lignin, cellulose and hemicellulose content of both cultivars. The maximum and the minimum lignin and cellulose content were observed in resistant and sensitive cultivars, respectively. In general, pre-harvest application of calcium (especially 1% CaCl2) with increasing of antioxidant enzyme activity and stem lignification led to decreasing of stem bending disorder in both cultivars.

FENOLOGIA DE <i>Poincianella pyramidalis</i> (TUL.) L. P. QUEIROZ E SUA RELAÇÃO COM A DISTRIBUIÇÃO TEMPORAL DA PRECIPITAÇÃO PLUVIAL NO SEMIÁRIDO BRASILEIRO

A região Semiárida brasileira tem como característica marcante a alta irregularidade da distribuição da precipitação pluvial no espaço e no tempo, com duas estações marcantes, a estação chuvosa, correspondente a um período curto com precipitações pluviais, erráticas e de intensidade muito variável, e a estação seca, período crítico, em geral, de prolongada estiagem, quando as espécies da Caatinga expressam sua fisionomia mais marcante, a caducifolia. As espécies vegetais, nestas condições, apresentam dinâmica de crescimento e desenvolvimento em consonância com os eventos de chuvas. Assim, o objetivo deste estudo foi caracterizar as fenofases de Poincianella pyramidalis e sua relação com a distribuição temporal da precipitação pluvial, que se dá em forma de pulsos. Para o acompanhamento fenológico, 32 indivíduos arbóreos foram selecionados, marcados e monitorados quinzenalmente, na Fazenda Açude, município de Soledade-PB. Para quantificar os eventos fenológicos, foram usados o percentual de intensidade de Fournier e o índice de atividade, registrando-se a presença e ausência das fenofases: brotamento, botão floral, floração (antese), frutificação e senescência, cujos dados foram relacionados com os pulsos e interpulsos de precipitação. Constata-se que as fenofases, brotamento, botões florais e floração em Poincianella pyramidalis se dão em sincronia com a distribuição temporal dos pulsos de precipitação pluvial na área de sua ocorrência. A intensidade e duração das fenofases do desenvolvimento em Poincianella pyramidalis dependem da amplitude e frequência dos pulsos de precipitação ao longo da estação chuvosa. A senescência total das folhas em Poincianella pyramidalisacontece quando os interpulsos de precipitação pluvial se intensificam à medida que avança a estação seca, caracterizando a caducifolia.

Ectopic Expression of Two FOREVER YOUNG FLOWER Orthologues from Cattleya Orchid Suppresses Ethylene Signaling and DELLA Results in Delayed Flower Senescence/Abscission and Reduced Flower Organ Elongation in Arabidopsis

Two orthologues of Arabidopsis FOREVER YOUNG FLOWER (FYF), CaFYF1 and CaFYF2, were identified from Cattleya intermedia. To investigate the function of these two genes, we performed ectopic expression of CaFYF1/2 in Arabidopsis. Delayed flower senescence and abscission were observed in 35S::CaFYF1/2 transgenic Arabidopsis plants. Furthermore, once CaFYF1/2 was fused with the strong repressor domain SRDX, severe delayed flower senescence and abscission were observed in 35S::CaFYF1/2+SRDX transgenic Arabidopsis plants. In contrast, when 35S::CaFYF1/2 was converted to a potent activator by fusion with the VP16-AD motif, flower senescence and abscission were promoted in these 35S::CaFYF1/2+VP16 transgenic dominant-negative mutant Arabidopsis plants. These results indicated that similar to Arabidopsis FYF, CaFYF1/2 also act as repressors in controlling floral organ senescence and abscission in transgenic Arabidopsis plants. The delayed senescence and abscission of the flower organs in 35S::CaFYF1/2 and 35S::CaFYF1/2+SRDX transgenic Arabidopsis plants were unaffected by ethylene treatment. Genes of the ethylene signaling and abscission-associated pathways, such as EDF1/2/3/4, BOP1/2, and IDA, were repressed in 35S::CaFYF1/2 and 35S::CaFYF1/2+SRDX transgenic Arabidopsis plants. Furthermore, 35S::CaFYF1/2 and 35S::CaFYF1/2+SRDX transgenic Arabidopsis plants showed additional morphological defects, such as short sepals and petals, which were correlated with the upregulation of the DELLA genes RGA, GAI, RGL1, and RGL2. These results suggested a possible role for Cattleya orchid CaFYF1/2 in controlling floral senescence/abscission by suppressing ethylene signaling and abscission-associated genes as well as controlling flower organ elongation through negative regulation of GA response by activating the expression of the DELLA genes during flower development.

Biochemical, physiological changes and antioxidant responses of cut gladiolus flower 'White Prosperity' induced by nitric oxide

Sodium nitroprusside (SNP), as nitric oxide (NO) donor, has been considered by postharvest researchers as one of the best option for slowing the processes controlling senescence in cut flowers. Here, we investigate the role of NO on postharvest physiology and vase life of the Gladiolus grandiflorus cv. White Prosperity. Vase life markedly extended by SNP at 150 μM from 3 day to 7.33 day and thus those inducer effects were dose- and time-dependent. SNP at 125 μM interdependent on vase life time period was observed to be the optimal dose for improving of relative fresh weight (RFW), peroxidase (POD), and total monomeric anthocyanin (TMA) in cut flowers. Supplementing vase solution with SNP indicated significant increase in water uptake of cut flowers and consequently protected to decline in RFW due to alleviate water losses stress. SNP was maintained the level of total soluble protein, lipid peroxidation, and POD, whereas it enhanced the level of catalase (CAT) and TMA in flower petals. Summary of our results revealed that SNP exogenous prolongs vase life via maintaining protein degrade, scavenging free radical in term of anthocyanin and enzymes antioxidant, decreasing polyphenol oxidase, inhibiting lipid peroxidation, and improving membrane stability in ‘White Prosperity’ cut flowers.

Involvement of Calcium and Calmodulin in Nitric Oxide-Regulated Senescence of Cut Lily Flowers.

Both nitric oxide (NO) and calcium ion (Ca2+)/calmodulin (CaM) have been shown to regulate the senescence of cut flowers. However, not much is known about the crosstalk between NO and Ca2+/CaM during the senescence of cut flowers. In this study, cut Oriental × Trumpet hybrid lily “Manissa” were used to investigate the roles and relationship between NO and Ca2+/CaM during postharvest freshness. The results show that the effects of CaCl2 or NO donor SNAP on the vase life, maximum flower diameter and hours until full opening were dose-dependent, with an optimum concentration of 20 mM CaCl2 or 100 μM SNAP. However, Ca2+ chelators EGTA or BAPTA/AM, Ca2+ channel inhibitors LaCl3 or nifedipine and CaM antagonists W-7 or TFP inhibited the promotion of SNAP. SNAP applied alone significantly increased the endogenous Ca2+/CaM contents in cut lily flowers, while EGTA, BAPTA/AM, LaCl3, nifedipine, W-7, and TFP decreased the advancement of SNAP. In addition, the SNAP-induced Ca2+-ATPase activity was more than twice as much as the control, but EGTA, BAPTA/AM, LaCl3, nifedipine, W-7, and TFP also reversed the enhancement. Moreover, EGTA, BAPTA/AM, LaCl3, nifedipine, W-7, and TFP prevented the SNAP-induced upregulation of gene expression of CaM, CBL1, and CBL3, which is associated with calcium signaling pathway. Overall, these results suggest that Ca2+/CaM may function as downstream molecules in NO-regulated senescence of cut flowers.

The influence of polyamine and polyamine inhibitors in herbaceous peony postharvest physiology

By spraying the exogenous polyamine spermidine (Spd) and the polyamine biosynthesis inhibitor d-arginine (d-Arg) in cut Paeonia lactiflora flowers, the dynamic change of superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA), soluble protein, endogenous polyamines and endogenous hormones were studied. The results showed that, the effect of exogenous polyamines and polyamine inhibitors could significantly affect the content of the vase life, which Spd decreased the vase life of flowers 1.4 days. d-Arg extended the vase life 1.8 days, improved the contents of soluble protein, activities of antioxidant enzymes, endogenous GA3, IAA, putrescine (Put), ZR and decreased the MDA content, endogenous ABA, Spd in cut herbaceous peony flowers. The effect of Spd and d-Arg might control the flower senescence through the way of affecting the hormones by affecting the endogenous polyamines or through the way of affecting the hormones and endogenous polyamines directly.

Hydrogen Sulfide: A Gaseous Molecule in Postharvest Freshness.

Hydrogen sulfide (H2S), as a signaling molecule, is involved in the regulation of growth and development in plants. Recent studies have indicated that H2S also plays important roles in regulating postharvest senescence of horticultural products. The focus of this review is to summarize the synthesis of H2S in plants and its potential roles in alleviating the senescence of cut flowers, fruits, and vegetables during postharvest storage. During postharvest of horticultural products, H2S could scavenge reactive oxygen species via promoting the activity of antioxidant enzymes, thereby, sustaining the integrity of the membrane. In fruits, H2S effectively enhanced the tolerance of chilling by increasing the content of proline and polyphenol compounds. During postharvest storage of perishable fruits and vegetables, H2S significantly alleviated decay, which was caused by fungi by inhibiting the growth of fungi spores. Moreover, H2S interacted with other molecules synergistically (NO) or antagonistically (ethylene) to alleviate senescence of horticultural products. At the transcriptional level, H2S regulated the expression of senescence-related genes, which were related to degradation of proteins and chlorophyll, to delay the senescence of horticultural products. Thus, H2S does not only possess positive antioxidant and antifungal properties, but also significantly regulates the senescence-related gene during postharvest of horticultural products. Future studies of H2S in postharvest storage should focus on its molecular mechanism in the posttranslational modifications of proteins as well as its safety attributes in treated fruits and vegetables.

Flower age expressed in thermal time: is nectar secretion synchronous with pistil receptivity in oilseed rape (Brassica napus L.)?

Floral longevity can vary substantially with temperature in a given plant species. Thermal time has been widely used to measure developmental age of plants and poikilothermic organisms. We tested whether thermal time was suitable to express flower age to characterise the duration of pistil receptivity and that of nectar secretion in undisturbed flowers of oilseed rape (OSR), and whether these two functional processes were synchronous. Flower age was measured in a male fertile hybrid F1 line and in its male sterile (MS) parental line to determine if the presence of pollen affected the nectar secretion period. Hand pollinations and nectar samplings were conducted throughout the lifespan of OSR flowers on several flower cohorts from plants grown under tunnels under various temperature conditions. The number of seeds produced per flower was used as a proxy to assess the level of pistil receptivity at the time of hand-pollination. Thermal time was more suitable than calendar time to express OSR flower age. A phase of maturity followed by a phase of senescence took place in the two processes, and both proceeded faster as temperature increased. Nectar was secreted during the phase of full pistil receptivity, and, in the MS line, was then reabsorbed during the gradual decline of pistil receptivity. However, the nectar secretion period was extended beyond the onset of pistil senescence in the F1 line. OSR flowers invest in nectar secretion to attract insect pollinators at least to cover the whole receptivity period of their female part. Nectar secretion may be prolonged in pollen-laden male fertile flowers to attract insect pollinators longer to ensure as long as possible the probability of their pollen being disseminated. Flower senescence is triggered by pistil senescence, while the presence of pollen in anthers acts as an inhibitor and therefore delays flower senescence. Thermal time should henceforth be used to express more universally the age of plant organs and to model the duration of processes in relation to temperature, especially in the advent of global warming.

RhERF113 Functions in Ethylene-Induced Petal Senescence by Modulating Cytokinin Content in Rose.

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.

Transcriptome profiling and identification of functional genes involved in H2S response in grapevine tissue cultured plantlets.

Hydrogen sulfide (H2S), a small bioactive gas, has been proved functioning in plant growth and development as well as alleviation of abiotic stresses, which including promoting seed germination, accelerating embryonic root growth, regulating flower senescence, inducing stomatal closure, and defending drought, heat, heavy metals and osmotic stresses etc. However, the molecular functioning mechanism of H2S was still unclear. The primary objective of this research was to analyze the transcriptional differences and functional genes involved in the H2S responses. In details, 4-week-old plantlets in tissue culture of grapevine (Vitis vinifera L.) cultivar 'Zuoyouhong' were sprayed with 0.1mM NaHS for 12h, and then transcriptome sequencing and qRT-PCR analysis were used to study the transcriptional differences and functional genes involved in the H2S responses. Our results indicated that 650 genes were differentially expressed after H2S treatment, in which 224 genes were up-regulated and 426 genes were down-regulated. The GO enrichment analysis and KEGG enrichment analysis results indicated that the up-regulated genes after H2S treatment focused on carbon metabolism, biosynthesis of amino acids, and glycolysis/gluconeogenesis, and the down-regulated genes were mainly in metabolic pathways, biosynthesis of secondary metabolites, and plant hormone signal transduction. Analyzing the transcription factor coding genes in details, it was indicated that 10 AP2/EREBPs, 5 NACs, 3 WRKYs, 3 MYBs, and 2 bHLHs etc. transcription factor coding genes were up-regulated, while 4 MYBs, 3 OFPs, 3 bHLHs, 2 AP2/EREBPs, 2 HBs etc. transcription factor coding genes were down-regulated. Taken together, H2S increased the productions in secondary metabolites and a variety of defensive compounds to improve plant development and abiotic resistance, and extend fruits postharvest shelf life by regulating the expression of AP2/EREBPs, WRKYs, MYBs, CABs, GRIP22, FERRITINs, TPSs, UGTs, and GHs etc.

Impact of GA3 and spermine on postharvest quality of anthurium cut flowers (Anthurium andraeanum) cv. Arizona

Abstract Anthurium cut flowers exposed to low temperatures may be subjected to chilling injury, whereas higher temperatures may accelerate their metabolism and induce premature senescence. Plant growth regulators, as gibberellic acid (GA3) and spermine (SPM), have been described to extend the postharvest life of flowers. In this study, both compounds were applied by spraying or pulsing in anthurium cv. Arizona before storage at 20 °C. The solutions were constituted of 144 μM GA3 and 2 μM SPM, which were used separately or in combination, and analyzed for 12 d. Spraying with GA3 + SPM extended the vase life and kept the commercial quality. These treatments increase the phenols content, as well as, the activity of polyphenol oxidase (PPO), peroxidase (POD), and superoxide dismutase (SOD). Spadix sprayed with GA3 or SPM retained high amounts of spermidine (SPD), and in the combination of GA3 + SPM, there were higher contents of spermidine. These results suggest that the application of GA3 + SPM by spraying can be used to reduce the senescence in anthurium cut flowers stored at 20 °C, and improve the commercial quality of the inflorescences.