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A pair of coumarin-based polycyclic meroterpenoid enantiomers (+)/(−)-gerbeloid A [(+)- 1a and (−)- 1b ] were isolated from the medicinal plant Gerbera piloselloides , which have a unique caged oxatricyclo [4.2.2.03,8] decene scaffold. Their planar and three-dimensional structures were exhaustively characterized by comprehensive spectroscopic data and X-ray diffraction analysis. Guided by the hypothetical biosynthetic pathway, the biomimetic synthesis of racemic 1 was achieved using 4-hydroxy-5-methylcoumarin and citral as the starting material via oxa-6 π electrocyclization and intramolecular [2 + 2] photocycloaddition. Subsequently, the results of the biological activity assay demonstrated that both (+)- 1a and (−)- 1b exhibited potent lipid-lowering effects in 3T3-L1 adipocytes and the high-fat diet zebrafish model. Notably, the lipid-lowering activity of (+)- 1a is better than that of (−)- 1b at the same concentration, and molecular mechanism study has shown that (+)- 1a and (−)- 1b impairs adipocyte differentiation and stimulate lipolysis by regulating C/EBP α /PPAR γ signaling and Perilipin signaling in vitro and in vivo. Our findings provide a promising drug model molecule for the treatment of obesity. A pair of unique caged coumarin-meroterpenoid enantiomers (+)/(−)-gerbeloid A were discovered from Gerbera piloselloides and synthesized biomimetically. (+)- 1a and (−)- 1b showed potent lipid-lowering activities in vitro and in vivo. [Display omitted] [ABSTRACT FROM AUTHOR]

• Salt stress resulted in reduction of growth, chlorophyll contents. • MT treatment alleviated the oxidative damage of gerbera. • MT regulates ion homeostasis and antioxidant strategy in response to salt stress. • MT pretreatment improves growth and biomass of gerbera under salt stress. Salt stress is a major abiotic stress factor that is increasing at a continuos pace and pressurizing global food security in view of climate change. Therefore, plant scientists are developing strategies to ameliorate the negative effects of salt stress on crop production. Melatonin (N-acetyl-5-methoxytryptamine; MT) is a vital biological hormone in plants that modulates growth, development, and tolerance to extreme environmental conditions. Its exogenous application is used to improve resistance to various stressors. Gerbera (Gerbera jamosonii L. cv. Yunnanhong) is a vital ornamental flower crop moderately sensitive against salt stress. A series of experiments were conducted on gerbera plants grown under NaCl stress (150 mM) with or in the absence of MT at 0.1 and 0.2 mM. It was shown that salt stress reduced growth and physiological traits but also caused oxidative stress, as recorded by the induction of oxidative stress markers in cell tissues. Foliar application of MT, especially at the concentration of 0.2 mM, boosted plant growth, biomass production, photosynthetic pigments, and ameliorated oxidative stress. The decrease in oxidative stress was associated with improved antioxidant activity linked to the production of the enzymes catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD). Exogenous MT also improved potassium (K+) uptake and restricted sodium (Na+) uptake in the leaves of gerbera. In conclusion, optimal MT application may serve as a potential ameliorator of salt-induced oxidative stress and help in the regulation of salinity for gerbera production under the threat of climate change. [ABSTRACT FROM AUTHOR]

• Present study report exclusive influence of meta -Topolin (m T) on in vitro regeneration of gerbera. • 100% regenerated plantlets were acclimatized in sand, soil, cow urine and tea leaves extract followed by sand-soil substrata. • Micromorphological studies on shoot, root and leaf revealed systematic plant growth. • Leaf gas exchange analysis revealed photosynthetic and transpiration activities accompanied by significant levels of photosynthetic pigments. • Clonal fidelity was ensured via cytology, flow cytometry, ISSR and SCoT markers. Present study reports meta -Topolin (m T)-induced in vitro mass propagation of Gerbera jamesonii Bolus ex Hooker f. (a cut-flower with high demand in the floriculture industry), subsequent acclimatization, and cyto-genetic fidelity assessment of the plantlets. Different cytokinins (and cytokinin-like plant growth regulators) i.e., 6-benzyladenine, kinetin, m T, thidiazuron and zeatin in variable doses (0.5–1.5 mg L−1) were supplemented in the basal Murashige and Skoog (MS) medium and comparative growth performance of the inoculated shoot tip explants were studied. Maximum number of de novo shoots (∼14) and leaves (∼40) were obtained in 1.5 mg L−1 m T. Earliest (∼9 days) root induction from shoot with maximum number (∼8) and length (∼6 cm) of roots were recorded in MS medium fortified with 1.5 mg L−1 indole-3-acetic acid. All the micropropagated plantlets (100%) were acclimatized in sand, soil, cow urine and tea leaves extract (1:1:1:1; v v −1) followed by sand-soil (1:1; v v −1) mixture. Histological studies on shoots, roots, and leaves along with leaf gas exchange analysis revealed a stimulated growth, cellular development, photosynthetic and transpiration activities accompanied by significant levels of photosynthetic pigments in plantlets during acclimatization. The flow cytometry-, cytology-, as well as Start Codon Targeted (SCoT) Polymorphism and inter simple sequence repeats (ISSR) marker-assisted fidelity assessments of the micropropagated plantlets exhibited ploidy as well as chromosomal stability, and monomorphic banding patterns confirmed no polymorphism within the plantlets and with their mother plant. The developed protocol should be of immense commercial importance to facilitate large-scale production of true-to-type planting materials of gerbera. [ABSTRACT FROM AUTHOR]

• Putrescine increases the rate of mycorrhiza colonization in the root. • Putrescine and mycorrhiza improved the quality of gerbera cut flowers. • Putrescine and mycorrhizal inoculation maintained the quality of gerbera cut flowers during vase life period. Effect of putrescine on the rate of mycorrhiza colonization in root and their effect on the growth and flowering process of gerbera 'Dune' was investigated in the form of factorial trial in a completely randomized design with three replications in a greenhouse. The factors were four concentrations of putrescine (0, 1, 2, and 4 mM) as foliar application and mycorrhizal fungus (without and with inoculation). The Mycorrhizal fungus was inoculated when plantlets transfer to pots, and two weeks after establishment; putrescine foliar application was performed every 15 days-interval for three months. Morphological and physiological characteristics measured in this research were included the number of flowers per plant, the time of bud formation until flowering, flower diameter, fresh and dry weight of flowers, flower longevity, total phenol, and leaf anthocyanin, as well as symbiosis percentages. The results showed that foliar application of putrescine increased mycorrhiza colonization in roots, and the highest colonization was obtained at the concentration of 2 mM putrescine application. Also, their interaction had a positive effect on other measured traits compared to the control. Putrescine and mycorrhiza increased the quality of gerbera cut flowers and reduced ions leakage, hydrogen peroxide, malondialdehyde, and lipoxygenase activity, and increased ascorbate peroxidase activity. [ABSTRACT FROM AUTHOR]

• First report on high cytokinin-induced hyperhydricity in gerbera. • Hyperhydricity resulted in delayed and poor regeneration, lower chlorophyll and higher relative water content. • Leaf folding, lower frequency and size of stomata, along with thinner, shorter and fewer roots observed in hyperhydric plants. • Identified key traits can be utilized to screen the hyperhydric plantlets at an early stage of growth for necessary remediation. Gerbera (Gerbera jamesonii Bolus) ranks amid the top five commercially preferred cut-flowers in global floriculture industry. Conventionally, gerbera is propagated by seed or by vegetative approaches. However, in vitro propagation cropped up as a better alternative with high commercial success since past two decades. Simultaneously, hyperhydricity of shoots has become a matter of serious concern during in vitro propagation. For the first time in gerbera, the present study highlights the morphometrical and physiological changes in hyperhydric shoots developed in high cytokinin-supplemented media. Four concentrations (2.5, 5, 7.5 and 10 mg L −1) of kinetin and N6-benzylaminopurine (BAP) were tested individually in supplementation with Murashige and Skoog basal medium. It was found that occurrence of hyperhydricity was significantly influenced by the type and concentrations of cytokinins used. Nevertheless, gradually increasing hyperhydricity along with significantly poorer multiplication were observed with the increasing concentrations of BAP and kinetin compared to its lower levels. Majority of explants in the presence of high levels (> 5 mg L −1) of kinetin or BAP became hyperhydric, losing their capability to regenerate. Hyperhydric plantlets exhibited lower chlorophyll and higher relative water content, resulting in glassy appearance of leaves and shoots with pale or yellowish green color accompanied with inward folding of the leaf blade towards the midrib. The roots of hyperhydric plantlets were thinner, shorter and fewer in number. Hyperhydricity further resulted in delayed development of plantlets as well as lower frequency and size of stomata. [ABSTRACT FROM AUTHOR]

• The application of pH with Ca on two gerbera was explored. • The application of pH alone or in combination increased the number of flowers. • The preharvest application of Ca improves the postharvest life of gerbera flowers. Among the various categories of plant biostimulants currently available on the market, protein hydrolysates, primarily composed of a heterogeneous mixture of peptides and amino acids, have gradually gained prominence. Nevertheless, the positive effects of these products on the production and longevity of cut flowers are still not well-explored. The purpose of this research was thus to fill this gap by assessing the impacts of a plant-derived protein hydrolysate, with and without the addition of calcium (PH and PH+Ca), on the growth, quality, and vaselife of two cultivars of gerbera with different pigmentation (Brunello and Tommy, red and yellow, respectively). Regardless of cultivar, foliar application of PH improved growth, flower production, absorption of key nutrients, and photosynthetic performance, compared to the control. On the other hand, the PH+Ca treatment exhibited the best results during vaselife. For both cultivars, the application of PH+Ca increased the durability of gerbera flowers, reducing the weight loss by an average of 19 % on day 10 compared to untreated flowers. Although cultivar-dependent, the positive effects of the PH+Ca biostimulant were also observed on petal pigmentation during vase life. For the Tommy cultivar, for instance, the Chroma values of treated flowers remained unchanged during the post-harvest period, unlike what was observed for untreated flowers. Therefore, considering the positive effects resulting from the use of PH and PH+Ca on gerbera, it would be interesting to further investigate the use of biostimulants in floriculture to increase the sustainability of the sector and especially with regard to cut flower production, without reducing or even improving the performance that is conventionally achieved. [ABSTRACT FROM AUTHOR]

• Here, the function of GhPOE1 on the senescence of Arabidopsis leaves was studied. • GhPOE1 is an ortholog of AT2G34700, which encodes a Pollen Ole e 1 domain protein. • GhPOE1 promoted leaves yellowing and the expression of SAG12, SAG13, WRKY53 , and SIRK. • GhPOE1 reduced chlorophyll content, Fv/Fm, and expression of CAB2 and RBCS in leaves. • GhPOE1 is a positive regulator capable of promoting leaf senescence in Arabidopsis. Senescence, the final stage of plant development, is a complex and highly controlled physiological process. Senescence occurs in various tissues and organs, and is especially apparent in leaves. Pollen Ole e 1 (POE1) proteins are known to initiate pollen germination, participate in the response to various stresses, and be involved in root development and seed germination. However, their role in plant senescence is not well defined. Using transcriptome data, we isolated a novel protein from Gerbera hybrida (gerbera) which is an ortholog of AT2G34700 (which encodes a Pollen Ole e 1 domain protein in Arabidopsis thaliana) and named GhPOE1. This protein is localized in the cytoplasm and expresses mainly in disk florets, old leaves, and old roots. We transformed GhPOE1 into wild-type Arabidopsis (Col-0) and obtained homozygous transgenic lines OE2, OE3 and OE5. Overexpression of GhPOE1 in these lines led to yellowing rosette leaves with decreased chlorophyll content and photochemical efficiency. Moreover, senescence-associated genes such as SAG12, SAG13, WRKY53 , and SIRK (senescence-induced receptor-like kinase) were significantly up-regulated, and the photosynthesis-associated genes CAB2 (chlorophyll a/b-binding 2) and RBCS (ribulose bisphosphate carboxylase small chain) were down-regulated in the transgenic plants. Our results showed that GhPOE1 is a positive regulator of senescence that can promote leaf senescence in Arabidopsis. GhPOE1 is a new candidate gene for genetic engineering to prolong the vase life of cut gerbera flowers. [ABSTRACT FROM AUTHOR]

• Our study constructed the first genome-wide simple sequence repeat (SSR) markers in G. hybrida. • The big population of 170 gerbera cultivars exhibiting distinct flower patterns and colors were used to analyze genetic variation and diversity. • We successfully constructed the first unique fingerprint map encompassing 170 gerbera germplasm lines, selecting 14 SSR markers for differentiating germplasm. • Our findings will provide valuable insights into the identification of gerbera germplasm resources and kinship studies among various groups. Gerbera hybrida is a highly sought-after cut flower globally, renowned for its diverse flower color and pattern resulting from its complex inflorescence meristem architecture. However, the scarcity of genomic information and molecular markers has impeded efforts to comprehend the genetic diversity of G. hybrida. To address this, our study aimed to construct genome-wide simple sequence repeat (SSR) markers in G. hybrida , utilizing genomic data from an inbred line. We employed 170 gerbera cultivars exhibiting distinct flower patterns and colors to analyze genetic variation and diversity. Our analyses revealed highly polymorphic SSR markers, a total of 69 alleles (Na) were amplified by 14 pairs of primers, in which polymorphic information content (PIC) ranging from 0.380 to 0.700 with an average value of 0.583. The polymorphic results of the observed heterozygosity (Ho) and Shannon's information index (I) were 0.499 and 1.195, respectively, showing a high level of genetic diversity within the enriched sequences of the G. hybrida genome. Leveraging these markers with strong differentiation, we successfully constructed a unique fingerprint map encompassing 170 gerbera germplasm lines. This study involved the construction of an SSR fingerprint library for G. hybrida germplasm resources, employing genetic analysis for screening and molecular-level identification. The findings provide valuable insights into the identification of gerbera germplasm resources and kinship studies among various groups. Moreover, this study lays a solid foundation for future advancements in molecular design breeding improvement and germplasm resource development in G. hybrida. [ABSTRACT FROM AUTHOR]

Phyllotaxis refers to the spatial arrangement of leaves and flowers on a stem. A recent study by Zhang et al. described the developmental process underlying phyllotaxis establishment in the capitulum of Gerbera hybrida. This work represents a cornerstone for studying the development and diversification mechanisms of capitula in the Asteraceae. [ABSTRACT FROM AUTHOR]

Abstract Gerbera (Gerbera jamesonii) is an important commercial species of cut flowers all around the world. Stem bending is a major disorder in cut gerbera flowers caused mainly by the lack of mechanical support in the flower stem. Lignin is the component of plant cell walls that provides strength. Three major enzymes comprise the pathway of lignin anabolism including peroxidase (POD), cinnamyl alcohol dehydrogenase (CAD), and cinnamoyl-CoA reductase (CCR). In this study, three overexpressed mutants for each of these major genes were generated and analyzed for their role in stem bending. Comparing the pod transgenic plants with ccr and cad mutants indicated that pod plants had the highest lignin content. Compared to wild-type (WT) plants, the highest vase life, membrane stability and solution uptake were obtained in gerbera pod mutants. Therefore, it appears that higher lignin contents can decrease stem bending and improve cell wall rigidity of cut gerbera flowers. These results also suggest that POD is a key gene in the biosynthesis of lignin in gerbera. [ABSTRACT FROM AUTHOR]

• The occurrence of stem bending varied significantly between gerbera cultivars. • Cut 'Kentucky' was prone to stem bending whereas 'Kimsey' was less prone to it. • Maximum breaking strength of stems became lower in 'Kentucky' compared to 'Kimsey'. • CaCl 2 treatment suppressed the occurrence of stem bending in 'Kentucky'. • CaCl 2 treatment increased stem diameter and maximum breaking strength in 'Kentucky'. Bacterial proliferation causes stem bending, which shortens the vase life of cut gerbera (Gerbera jamesonii Bolus ex Hook. F.). We investigated the effect of an antimicrobial compound on the symptoms of ornamental value loss using 8 gerbera cultivars. In five different cultivars, the vase life of 11–44% and 11% cut flowers held in distilled water and antimicrobial solution, respectively, was terminated by stem bending. To explore in detail variations in the occurrence of stem bending under condition in which bacterial proliferation is suppressed, the occurrence of stem bending was investigated using cut flowers from 31 cultivars in the presence of the antimicrobial compound. The occurrence of stem bending varied significantly between cultivars. Following that, the stem diameter, stem elongation, and maximum breaking strength of stems were investigated using 'Kentucky', which is prone to stem bending, and 'Kimsey', which is less prone to it. The flower stem diameter of 'Kentucky' became smaller than that of 'Kimsey'. In addition, the maximum breaking strength of the stem became lower in 'Kentucky' compared to 'Kimsey'. Treatment with calcium chloride (CaCl 2) suppressed the occurrence of stem bending in 'Kentucky'. In 'Kentucky' and 'Kimsey', CaCl 2 treatment suppressed transpiration and increased stem diameter and maximum breaking strength. These results suggest stem bending in cut gerbera 'Kentucky' may be caused by a decrease in flower stem diameter and a weakening of stem strength under conditions of suppressing bacterial proliferation. [ABSTRACT FROM AUTHOR]

The relation between bacteria numbers in vase water and vase life of gerbera cut flowers has recently been challenged because of reported negative effects of bactericidal compounds. This relation is investigated using two types of experiments that do not rely on antimicrobial compounds. The first type controls vase water temperature (4, 15, 22 or 28 °C) independently from air temperature (15, 22 or 28 °C) to investigate whether fresh weight behavior for two mini gerbera cultivars (‘Okidoki’ and ‘Kimsey’) is affected by bacterial growth and leaking of soluble sugars in the vase water, or by senescence of the flower head. Fresh weight loss, when compared at constant water temperatures, was higher at higher air temperatures. At higher water temperatures and constant air temperatures fresh weight loss was not higher, although bacterial levels were high enough to expect water uptake issues. Also sugar consumption in the vase water depended on water temperature. This indicates that senescence was the main reason for the decline in fresh weight for these flowers, not bacterial growth. The second type of experiments was based on adding predetermined levels of bacteria (0, 10 3 or 10 5  CFU mL −1 ) and sugars (0.1% glucose or 0.2% sucrose) into vase water of flowers of three large-bloomed (‘Carambole’, ‘Candela’ and ‘Iceberg’) cultivars harvested with closed stem-ends and had their scapes sterilized before the start of vase life. When bacteria were added varying types of responses were observed. ‘Carambole’ flowers showed lower water uptake and lower transpiration and, early scape bending. Petal wilting was observed for ‘Candela’ flowers. ‘Carambole’ flowers showed higher scape sugar leakage levels in the vase water while ‘Candela’ flowers had higher scape firmness. ‘Iceberg’ flowers were also affected by bacteria, resulting in early scape bending, although sugar levels in the vase water were low. Furthermore, adding sucrose and/or bacteria in the vase water of one ‘Iceberg’ and one ‘Carambole’ flower in the same flask resulted in later scape bending for ‘Iceberg’ flowers compared to having two ‘Carambole’ or two ‘Iceberg’ flowers. The results indicate that bacteria interactions with gerbera flowers depend strongly on genotype. [ABSTRACT FROM AUTHOR]

Stomata present on leaves are the main channels for water vapor exchange between the plant and atmosphere, and contribute to water loss of cut flowers. Although cut gerberas ( Gerbera jamesonii Bolus) are commonly composed of a terminal composite floral head and a scape, and have no leaves, they are also prone to severe water deficits, presumably resulting from water loss exceeding water uptake. We have investigated the distribution and characteristics of stomata of cut ‘Real’ gerberas, and their response to light and abscisic acid (ABA) treatments, to increase understanding of their functionality in postharvest water loss. Stomata were widely distributed on various parts of floral organs and the scape in cut gerberas, including the lower epidermis of the ray floret petals, trans florets, disc florets, lower epidermis of sepals, and the uppermost and middle parts of scape surfaces. The highest stomatal density was observed on the lower epidermis of sepals. Cut gerberas had the largest stomata on the middle scape surface and the smallest on the surface of the uppermost scape. Nonetheless, the lower epidermis of sepals had the highest relative stomatal area, which was higher than that of the other parts. Additionally, the lower sepal epidermis had the highest maximum stomatal conductance of water vapor (g wmax ), and which was higher than that of the lower and upper leaf epidermis. The opening of stomata on various parts of cut gerberas differed in their response to light, and the highest percentage of open stomata and largest aperture were found in the stomata on the lower epidermis of sepals. Changes in water loss in cut gerberas exhibited a distinct circadian rhythm over a four-day vase period with an alternating 12-h light/dark cycle. In the lower epidermis of sepals, ABA painting treatment significantly inhibited stomatal opening and reduced water loss in cut gerberas over a 6 h light period. These findings imply the critical involvement of stomata on the lower epidermis of sepals in water loss of cut gerberas, and improve our understanding of the mechanism underlying their water deficit symptoms. [ABSTRACT FROM AUTHOR]

Senescence is a major problem of gerbera ( Gerbera jamesonii ) cut flowers limiting their long-distance transportation and subsequent marketing. This study was designed to evaluate whether external application of nitric oxide (NO), provided through 150 μM sodium nitroprusside (SNP), could extend the vase life of gerbera cut flowers, as well as the potential physiological and biochemical mechanisms involved. We used two gerbera cultivars ‘Bayadère’ and ‘Sunway’; watered ‘Bayadère’ cut flowers have a better performance than watered ‘Sunway’ cut flowers. NO extended the vase life of cut flowers of both cultivars as compared with their respective control treated with water alone, with ‘Sunway’ showing better postharvest performance than ‘Bayadère’. Application of SNP in vase solution resulted in a decrease in proline content in the stems of cut flowers of both cultivars, providing evidence for alleviation of water deficit in SNP-supplied cut flowers. Improved postharvest performance of SNP-treated gerbera cultivars could be attributed to increases in total phenol and flavonoid contents, which resulted from decreased polyphenol oxidase activity and increased phenylalanine ammonia-lyase activity. A decline in malondialdehyde accumulation in the stems of SNP-treated cut flowers was greater in ‘Sunway’ flowers than in ‘Bayadère’ flowers, which was ascribed to the better performance of antioxidant systems in SNP-treated ‘Sunway’ flowers to reduce the adverse effect of oxidative stress. Taken together, exogenous NO might be promising approaches to improve postharvest performance of flowers. [ABSTRACT FROM AUTHOR]

The chalcone synthase superfamily consists of type III polyketidesynthases (PKSs), enzymes responsible for producing plant secondary metabolites with various biological and pharmacological activities. Anther-specific chalcone synthase-like enzymes (ASCLs) represent an ancient group of type III PKSs involved in the biosynthesis of sporopollenin, the main component of the exine layer of moss spores and mature pollen grains of seed plants. In the latter, ASCL proteins are localized in the tapetal cells of the anther where they participate in sporopollenin biosynthesis and exine formation within the locule. It is thought that the enzymes responsible for sporopollenin biosynthesis are highly conserved, and thus far, each angiosperm species with a genome sequenced has possessed two ASCL genes, which in Arabidopsis thaliana are PKSA and PKSB. The Gerbera hybrida (gerbera) PKS protein family consists of three chalcone synthases (GCHS1, GCHS3 and GCHS4) and three 2-pyrone synthases (G2PS1, G2PS2 and G2PS3). In previous studies we have demonstrated the functions of chalcone synthases in flavonoid biosynthesis, and the involvement of 2-pyrone synthases in the biosynthesis of antimicrobial compounds found in gerbera. In this study we expanded the gerbera PKS-family by functionally characterizing two gerbera ASCL proteins. In vitro enzymatic studies using purified recombinant proteins showed that both GASCL1 and GASCL2 were able to use medium and long-chain acyl-CoA starters and perform two to three condensation reactions of malonyl-CoA to produce tri- and tetraketide 2-pyrones, usually referred to as alpha-pyrones in sporopollenin literature. Both GASCL1 and GASCL2 genes were expressed only in floral organs, with most expression observed in anthers. In the anthers, transcripts of both genes showed strict tapetum-specific localization. [ABSTRACT FROM AUTHOR]

• AgNPs enhanced shoot multiplication and CoNPs enhanced in vitro rooting and subsequent growth. • Abnormal phenomena (vitrification, yellowing of the leaf and browning of the explant) reduced in the rooting stage. • Ethylene, cellulase and pectinase activities reduced and antioxidant activity increased in the rooting stage. The effects of silver nanoparticles (AgNPs) and cobalt nanoparticles (CoNPs) in Murashige and Skoog (MS) medium were investigated with regard to shoot multiplication, in vitro rooting, acclimatization, growth and flowering of Gerbera (Gerbera jamesonii Revolution Yellow) cultivar. The results showed that AgNPs had effects on the shoot multiplication stage, while CoNPs had effects on the in vitro rooting, acclimatization, growth and flowering stages. Single shoots grown on MS medium supplemented with 2 mg L−1 AgNPs recorded optimal shoot multiplication efficiency, with shoots taller than 2 cm in height as well as reduced vitrification and yellowing of the leaf after 4 weeks of culture. In addition, the 2.5 cm shoots cultured on MS medium with 0.0465 mg L−1 CoNPs being used instead of CoCl 2.6H 2 O gave rooting two days earlier and improved in vitro rooting. Moreover, reduction in vitrification, yellowing of the leaf and browning of the explant were observed in the rooting stage. There were reductions in ethylene accumulation and cellulase and pectinase enzyme activities, while the antioxidant activity increased in the rooting stage after 4 weeks, and this all enhanced the survival rate of plantlets in the acclimatization at the nursery stage. [ABSTRACT FROM AUTHOR]

1H-NMR guided fractionation led to the isolation of twenty-two coumarin monoterpenes from the whole plant of Gerbera piloselloides , among which fourteen were undescribed. All coumarin monoterpenes were initially found to be racemates without optical activity. Subsequently, eleven pairs of optically pure enantiomers were successfully separated by chiral phase HPLC. Their structures and absolute configurations were unambiguously determined based on their spectroscopic data, calculated/experimental electronic circular dichroism (ECD) data, and X-ray diffraction analysis. Bioassays in LPS-treated RAW 264.7 cells revealed that the four compounds possessed moderate anti-inflammatory activity. In addition, the correlations between the cotton effect (CE) from δ -lactone at approximately 210–220 nm in CD spectra and γ-C or the ring fused at γ-C of the skeleton were reported for the first time. [Display omitted] • 1H-NMR guide isolation of eleven pairs of enantiomeric coumarin monoterpenes. • Seven undescribed pairs of enantiomeric coumarin-monoterpenes were separated. • The γ -C makes great contribution for the cotton effect of δ -lactone. [ABSTRACT FROM AUTHOR]

The species of Gerbera sect. Gerbera are revised in light of collections made over the past 30 years following the last revision of the group, at which time five species were recognized. We now recognize eight species in the section. Most of the species are obligate pyrophytes, flowering only in the spring and summer following a burn. Populations from the Cederberg, Olifants River Mountains and Piketberg previously included in Gerbera crocea but anomalous in that species in their sinuately incised leaves with whitish-grey felted under surface are segregated as Gerbera sinuata . The disjunct Eastern Cape populations of Gerbera tomentosa lack the imbricate involucral bracts diagnostic for that species and are segregated as Gerbera ovata , a new name for G. tomentosa var. elliptica , characterized by small, ovate leaves with involute margins. Gerbera grandis is a new species from the Klein River Mountains recognized by its large size, lanceolate leaves, and long, subulate involucral bracts. We also correct the recorded distribution of G. crocea and G. tomentosa , and transfer the name G. sinuata var. undulata from G. crocea to synonomy under Gerbera viridifolia . All species are fully described and mapped, and a key to their identification is provided. [ABSTRACT FROM AUTHOR]

The vase life of cut Gerbera flowers ( Gerbera jamesonii cv. Tamara) is often short due to stem bending. The purpose of this study was to find a pulse treatment, to be applied directly after harvest, which would delay this bending. Bending was hypothesized to be due, at least in part, to a xylem blockage by bacteria (leading to early turgor loss), to lack of osmotic pressure, and to lack of cell wall stiffness. Chemicals tested included antimicrobial compounds, surfactants (to bypass xylem occlusion), sugars, inorganic ions, and chemicals affecting cell wall rigidity. When used as a pulse treatment, antimicrobial compounds such as chlorine and silver ions had no effect. Only a buffer at pH 3.0–3.5, which inhibits bacterial growth, delayed bending. A range of surfactants tested, many of which had antimicrobial activity, had no effect. Sugars delayed the time to bending, if accompanied by an efficient antimicrobial compound. Cell wall rigidity can be affected by calcium ions and H + concentration. Treatment with calcium chloride delayed bending. Vanadate, an inhibitor of H + transport to the cell wall, almost completely prevented stem bending, but resulted in unwanted petal discoloration. By contrast, fusicoccin, a promoter of H + transport to cell walls, drastically hastened bending. A mixture of chemicals (50 mM calcium chloride, 25 g L −1 sucrose, buffered at pH 3.5 by citric acid and K 2 HPO 4 ) was satisfactory as a 24 h pulse treatment, prior to 24 h of dry storage at 20 °C and vase life at 20 °C. It delayed the time to bending during vase life in cv. Tamara and six other cultivars tested which are prone to stem bending. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO 2 ) enrichment are widely reported to stimulate the plant growth. However, those relative studies in the horticultural plants are quite limited, particularly about the interaction of CO 2 and the physiological phenomenon “midday depression”. Herein, daytime (T1, 7:00–19:00) and morning (T2, 7:00–12:00) CO 2 enrichment treatments (800 ± 50 μmol mol −1 ) were conducted in open-top plastic greenhouses to investigate their effects on photosynthesis and growth in Gerbera jamesonii , compared to the atmospheric CO 2 concentration (CK, approximately 400 μmol mol −1 ). The results showed that the leaf net photosynthetic rate (Pn) of G. jamesonii was averagely increased 52 ± 17% in T1 and 66 ± 8% in T2 by CO 2 enrichment, which remarkably higher ( P < 0.05) in T2 than that in T1 in the later period of the experiment (30–150 d). CO 2 enrichment also significantly increased ( P < 0.01) the contents of photoassimilates (soluble sugar, starch, and chlorophyll), but decreased the contents of soluble proteins ( P < 0.05). The biomass determination in T1 and T2 revealed that plant dry weight was raised 40 ± 9% and 32 ± 6% on 150 days, respectively. In addition, CO 2 enrichment enhanced the quantities and qualities of flowers ( P < 0.05), such as augmented the flower number and size, extended the peduncle length, accumulated anthocyanin concentrations, and prolonged the flower vase life. Even though there were no significant differences between day and morning CO 2 enrichment on the basis of the statistical data, the morning CO 2 enrichment exhibited more favorable cost savings. According to these positive responses, we considered that the morning CO 2 enrichment has a potential application in commential production of G. jamesonii . [ABSTRACT FROM AUTHOR]

Highlights: [•] Stem bending in Gerbera flowers was not delayed or hastened by relatively high concentrations of some antimicrobial compounds. [•] Lack of a positive effect of the compounds on bending was accompanied by visible damage on the stem ends. [•] This toxicity was alleviated by addition of sucrose. [•] The data suggested an effect other than bacteria, probably due to material from dead stem cells that induced xylem blockage. [ABSTRACT FROM AUTHOR]

Highlights: [•] Sucrose in the media increases in vitro development of gerbera plantlets in growth room and greenhouse conditions. [•] Greenhouse growth of in vitro plantlets improved development without contamination problems. [•] Sucrose concentration affected stomatal development and osteole aperture. [•] Best plantlet acclimatization was in sugar-free medium in the greenhouse. [•] In vitro greenhouse culture is an alternative to photoautotrophic culture with reduced micropropagation costs. [ABSTRACT FROM AUTHOR]

Abstract: Gerbera jamesonii (gerbera) is an important cut-flower in the global floricultural industry. Micropropagation is the main system used to clonally propagate gerbera in vitro resulting in the production of millions of plantlets each year. Numerous types of explants and protocols for micropropagation have been established and used for gerbera. Shoot tips are the commonly used explant while adventitious shoot induction from the capitulum is also a popular method. Most papers in the literature have focused on testing the influence of different types and combinations of plant growth regulators with the aim of improving the regeneration and multiplication stage of one or few cultivars. Genotype is one of the most influential factors on the response of gerbera in vitro. Despite this, no successful universal protocol has yet been developed for multiple cultivars, limiting the usefulness of current protocols for commercial biotechnology labs. Slow-growing endogenous bacteria are one of the most important problems in gerbera micropropagation but require more studies on control and prevention. Individual shoots are normally easy to root, usually in excess of 90% of plantlets, but the acclimatization stage requires improvements and new technologies to increase the survival of plants. Epigenetic variations in micropropagated gerbera are frequently observed only with high concentrations of cytokinins in the culture medium but somaclonal variation is rare. [Copyright &y& Elsevier]

• P. indica significantly increased the transplanting survival rate of tissue cultured gerbera seedlings, and improved the aboveground fresh weight, underground fresh weight and chlorophyll content of the fungus colonized transplanted seedlings (PI). • Although P. indica showed no obvious antagonistic effect on Phytophthora cryptogea (the causal agent of gerbera root rot disease), P. cryptogea inoculated PI seedlings (PP) showed much milder diseased symptom compared with the P. cryptogea inoculated seedlings (PC). • P. indica appeared to improve the plant growth and confer gerbera with root rot tolerance through increasing POD, CAT and SOD activities and stimulating IAA and GA accumulation, and suppressing ABA and JA biosynthesis. P. indica can confer gerbera with root rot resistance. Piriformospora indica , a root endophytic fungus with growth-promoting and resistance-enhancing effects on host plants, has been successfully applied as natural biofertilizer and biological control agent. In this study, the effects of P. indica on the growth and root rot disease resistance of gerbera plants were investigated. Results showed that P. indica significantly increased the transplanting survival rate of tissue cultured seedlings, and improved the aboveground fresh weight, underground fresh weight, Fv/Fm and Y(II) values and chlorophyll content of P. indica colonized transplanted seedlings (PI). Although P. indica showed no obvious antagonistic effect on Phytophthora cryptogea, P. cryptogea inoculated PI seedlings (PP) showed much milder diseased symptoms compared with the P. cryptogea inoculated seedlings (PC). The P. indica colonization significantly increased the activities of SOD, CAT, POD and PAL, but greatly suppressed the MDA and H 2 O 2 accumulations in gerbera root. The contents of some growth promoting phytohormones, such as IAA and GA, were induced by P. indica , while the ABA and JA contents was significantly inhibited. After P. cryptogea inoculation, the SOD, POD, CAT and PAL activities and IAA and GA contents decreased in PC but increased in PP. Besides, ABA and JA contents in PP were significantly lower than in PC. Our results indicated that P. indica improved the gerbera growth by increasing chlorophyll content, photosynthetic characteristics and growth-beneficial phytohormones' accumulations. Moreover, it appeared to confer gerbera with root rot resistance through increasing POD, CAT and SOD activities, stimulating IAA and GA accumulations, and suppressing ABA and JA biosynthesis. [Display omitted] [ABSTRACT FROM AUTHOR]

Highlights: [•] Greenhouse soilless gerbera was grown in autumn and spring with fresh or moderately saline water. [•] The Penman–Monteith model and two regression equations, which responded to vapour pressure deficit and/or radiation, were used to predict the hourly transpiration rate. [•] Water salinity affected crop growth and production only in spring, but it influenced neither stomatal resistance nor model calibration. [•] The models explained 80–96% of the variability of measured transpiration. [ABSTRACT FROM AUTHOR]

Abstract: We studied stem bending in cut Gerbera flowers (Gerbera jamesonii cv. Tamara). Bending might be due to turgor loss. During vase life water uptake decreased more rapidly than transpiration, hence the flowers lost water. Net water loss did not occur in the floral head, but was found in the stem. It was largest in the segment (10–15cm below the floral head) where bending was localised. When comparing flowers that showed stem bending with those that did not, on day 7 of vase life, the fresh weight loss of 5cm stem segments was higher in the stems that had bent. Covering the stems with a flexible, thin sleeve of polypropylene plastic reduced transpiration and increased the time to stem bending from d 7 to d 14 of vase life. Additionally, stem bending might relate to stem elongation and to stem morphology and anatomy. Stems elongated by 1–1.5cm, in the uppermost 10cm, during the first two days of vase life. No relationship was found between stem elongation and bending. At harvest, the stems contained a large central cavity, starting at about 5cm from the root–shoot junction, and ending about 10cm below the floral head. The cavity extended upwards and laterally during vase life, but no relationship was found between cavity formation and stem bending. A cylinder of sclerenchyma in the stems was found to end about 20cm below the floral head, in summer. Bending was correlated with the extent of sclerenchyma formation and stem lignin levels. It is concluded that stem bending is due to net water loss from the stem, particularly in the area of bending, and to low mechanical strength in the upper part of the stems, which lack a sclerenchyma cylinder. [Copyright &y& Elsevier]

Abstract: Improving disease resistance has become an important breeding objective in gerbera, one of the most important floricultural crops in the world. Development and application of molecular markers are expected to assist selection of gerberas with improved disease resistance. The availability of resistance gene candidate (RGC) sequences has accelerated the development of molecular markers for disease resistance traits in numerous plants. In this study, 84 gerbera RGC sequences (GhRGCs) were identified from cloned PCR products amplified from powdery mildew (PM)-resistant gerberas with degenerate oligonucleotide primers from two conserved motifs of plant disease resistance genes (R-genes). Nineteen GhRGC sequences could be translated into polypeptides with ≤90% amino acid identity. Multiple sequence alignment analysis of the 19 representative polypeptide sequences suggests two major clusters of gerbera RGCs. Twelve GhRGCs in cluster 1 contain the typical motifs of the toll and interleukin receptor–nucleotide binding site–leucine-rich repeat (TIR–NB–LRR) class R-genes within the nucleotide-binding site (NB) domain, and the seven GhRGCs in cluster 2 possess the typical motifs of the coiled coil–nucleotide binding site–leucine-rich repeat (CC–NB–LRR) class R-genes in the NB domain. The 19 GhRGCs were further divided into nine sub-families that share 15–50% amino acid identity. Thirty specific oligonucleotide primers were designed from 15 GhRGCs and tested on gerbera breeding line UFGE 4033 and ‘Sunburst Snow White’ that are PM-resistant and PM-susceptible, respectively, and are parents of two mapping populations for developing molecular markers for PM resistance. One sequence characterized amplified polymorphism (SCAR) and 11 cleaved amplified polymorphic site (CAPS) markers were developed and were polymorphic between the two parents. When used with the target region amplification polymorphism (TRAP) marker system, the 30 GhRGC-derived primers detected 242 additional DNA bands that were polymorphic between UFGE 4033 and ‘Sunburst Snow White’. This study represents the first effort to sample and characterize R-gene candidate sequences in gerbera. The obtained sequences may provide a valuable entry point to obtain full-length or additional sequences of gerbera NB–LRR genes. The SCAR, CAPS and TRAP markers developed may be valuable for mapping of genes or quantitative trait loci responsible for disease resistance in gerbera. [Copyright &y& Elsevier]

Abstract: Gerbera is one of the most important floricultural crops worldwide, yet few robust and informative molecular markers were available for use in gerbera breeding and genetic studies. Previously we reported the first set of 99 EST-SSR markers. This study further characterized these markers using a much larger group of gerbera accessions and selected 53 robust, informative markers. The selected markers each amplified two to seven alleles, their PIC value ranged from 0.207 to 0.771, observed heterozygosity from 0.100 to 0.775, and expected heterozygosity from 0.224 to 0.801. Observed heterozygosity varied considerably among gerberas, ranging from 0.245 to 0.615. Similar levels of genetic diversity (observed and expected heterozygosity and Shannon''s index) were observed among groups of gerberas for different uses (breeding lines, cut flower, seed-propagated pot-type, and tissue culture-propagated pot-type). The selected markers unequivocally differentiated all gerberas in the study, including six pairs of highly similar varieties that were indistinguishable morphologically. The great majority of the 861 pairwise comparisons among the 40 gerbera accessions showed a Jaccard similarity coefficient between 0.290 and 0.700 and a few pairs between 0.800 and 0.970. The UPGMA dendrogram based on similarity coefficients and population inference analysis with STRUCTURE separated the gerbera accessions into two major clusters that largely correspond to breeding approaches and/or propagation methods. These results showed that the selected markers were very powerful for discriminating gerberas and revealed genetic structures in cultivated gerberas. Application of these markers may also facilitate assessment of clonal fidelity and future DUS tests in gerberas. [Copyright &y& Elsevier]

Abstract: UV-C (λ =254nm) irradiation was effective in reducing Botrytis cinerea floret specking (i.e., lesion development) and maintaining a better postharvest quality of cut gerbera flowers. A range of UV-C doses (0.5–10.0kJm−2) was tested on ‘Ice cream’ and ‘Ecco’ gerbera flowers to activate germicidal and inducible defence mechanisms. Irradiation of B. cinerea cultures with 0.5, 1.0, 2.5 and 5.0kJm−2 UV-C resulted in up to a 10-fold reduction of conidial germination percentages and significant (P <0.05) delay of mycelium growth, compared to the non-irradiated control cultures. Moreover, lesion diameters on gerbera florets inoculated with UV-C irradiated B. cinerea cultures were reduced by up to 70%, suggesting that UV-C had a negative effect on the pathogenic strength of the fungi. Lesion diameters on florets of UV-C irradiated gerberas were reduced by up to 55% giving evidence that defence responses in the host tissue were induced. Concentration of total phenolics seemed to be unaffected by 0.5kJm−2 UV-C treatment in both cultivars, but polyphenol oxidase (PPO) activity increased and remained higher compared to the non-irradiated control flowers throughout the 48h storage period at 20°C. The increase of PPO suggests that this enzyme might play an important role in host defence mechanisms that suppressed B. cinerea floret specking. Gerbera flowers irradiated with 1.0 or 10.0kJm−2 UV-C showed improvement in vase-life by 1.8 and 2.4 d, decrease in stem break percentages by 43 and 29% and delay in stem break incidence by 3.3 and 1.3 d, respectively. [Copyright &y& Elsevier]

Abstract: Greenhouse technology provides favorable microclimate for year round cultivation of crops. Floricultural production in the greenhouse is an attractive venture for subtropical India due to its economic and aesthetic value. However, production and quality of flowers suffer due to high summer temperatures. Hence, development of a reliable model to predict the microclimate of greenhouse is necessary to manage the crop production and to optimize the design. Experiments were conducted in two different shape and size of greenhouses to evaluate the microclimate and crop performance. A simple dynamic model was developed to predict air temperature, vapor pressure and canopy temperatures. Submodels of natural ventilation and crop transpiration constituted the sensible and latent heat transfers in the greenhouse. The model was validated for Gerbera crop cultivation during winter and summer seasons. Good agreement was found between the predicted and observed values of temperature with RMSE values of 0.73°C and 0.87°C during winter and summer seasons, respectively. Sensitivity analysis of the model showed that width of side opening and angle of roof vent influenced the model performance considerably. It was concluded that the model can be used as a design tool for prediction of microclimate in the greenhouse for floricultural production. [Copyright &y& Elsevier]

Abstract: In greenhouse production most floricultural crops are cultivated in soilless substrates with limited concentrations of the beneficial element silicon (Si). Inclusion of supplemental silicon in greenhouse production is reported to affect the quality of several herbaceous plants that accumulate Si in their tissue. The goals of this study were to evaluate the effects of different Si sources and concentrations on the floricultural quality traits, the Si accumulation in plant tissues and the leaf tissue concentrations of other elemental nutrients of greenhouse produced gerbera (Gerbera hybrid L. ‘Acapella’). Potassium silicate (KSiO3) substrate incorporation or weekly substrate drench, sodium silicate (NaSiO3) foliar application, and rice husk ash substrate incorporation were used as Si supplements. Gerbera plants supplemented with several Si source and rate combinations, particularly NaSiO3 foliar sprays, produced thicker flower peduncles, increased flower diameters, increased height, and flowered earlier than non-supplemented controls. Gerbera plants grown in Si-supplemented media all accumulated higher levels of silicon in leaf, peduncle and flower tissues than non-supplemented controls. Leaf concentrations of macronutrients, such as sulfur and potassium, and micronutrients such as, boron, copper, iron, and manganese, were slightly changed among Si-supplemented plants. Foliar sprays of NaSiO3 at a rate of 150mgSiL−1 caused stem shortening and flower deformation. However, silicon supplements can improve the floricultural traits of greenhouse grown gerberas, but forms and rates of Si must be optimized. [Copyright &y& Elsevier]

Abstract: Nanometer-sized silver (Ag+) particles (NS) are used in various applications as an anti-microbial. Effects of NS (2–5nm diam.) pulse solution treatments on vase life of cut gerbera (Gerbera jamesonii) cv. Ruikou flowers were investigated. Compared with the control [pulsed with deionised water (DI) and subsequently held in DI] pulsing for 24h with 5mg/L NS solution followed by holding in DI maintained water uptake and extended vase life. From in vitro and microscopy assessments, NS pulse treatment inhibited bacteria growth in the vase solution and at cut stem ends during the first 2d of the vase period. [Copyright &y& Elsevier]

Abstract: Nutrient deficiencies usually constrain the use of some composted materials as peat-substitute growing media even if some fertilizer is applied to the media. In this work, we assessed the suitability of various composted materials as such or mixed with peat for potted plant production, with special emphasis on their effects on nutrient availability to plants. Further, we examined the effect of vivianite [Fe3(PO4)2·8H2O] as a fertilizer and its mixture with humic substances (HS) on these growing media (particularly their effectiveness in preventing Fe deficiency chlorosis in alkaline substrates). A completely randomized experiment design was developed involving the growth of gerber (Gerbera jamesonii H. Bolus) and two factors, namely (i) the growing medium, specifically composted cork residue (C), compost obtained from a mixture of olive husk and cotton gin trash mixed with rice hulls and peat in a 1:1:1 volume proportion (OH), composted grape marc (GM), Sphagnum peat mixed with spent mushroom compost (M), coconut fibre (CF), and Sphagnum peat; and (ii) the Fe source (control without Fe, Fe-EDDHA, vivianite and vivianite+HS in a weight ratio of 10:1). The highest chlorophyll meter readings were provided by the two media with the lowest pH (peat and CF), and the lowest readings were provided by the medium exhibiting the highest pH (C). Composted grape marc (GM) and M provided the largest amounts of dry matter (DM), whereas peat and M gave the highest flower yields. Flower and DM yield were lower in CF and C than those in other substrates; the low production in the former can be ascribed to Ca deficiency; in fact, the medium was poor in this nutrient; therefore, plants grown on it exhibited low Ca concentration in leaves. On the other hand, the low chlorophyll meter readings and DM yield in C can be largely ascribed to Fe deficiency chlorosis since the application of Fe improved both the parameters, the best results being obtained with the vivianite+HS mixture. Vivianite-based treatments increased P concentrations in leaves, but only in more acidic medium (CF and peat), where the pH of the media facilitated the dissolution of the product. The adverse effects of Fe sources on the Mn and Zn concentrations in leaves were as a result of the antagonistic effect of the Fe supply, which varied with the particular growing medium: Fe-chelate depressed Mn in plants grown on C, whereas vivianite+HS decreased the Mn concentration in plants grown on GM. The results obtained with the different compost-based materials studied and the ability to overcome Fe deficiency in C by using a vivianite+HS mixture are interesting with a view to reduce the use of peat in the potted plant industry. [Copyright &y& Elsevier]

Abstract: The aim of this study was to evaluate the efficacy of silver nanoparticles (SNP) and essential oils as novel antimicrobial agents in extending the vase-life of gerbera (Gerbera jamesonii cv. ‘Dune’) flowers. The vase-life of flowers held in a solution containing 5mgL−1 SNP plus 6% sucrose was found to be significantly higher than with 8-HQC (8-hydroxyquinoline citrate) or control treatments. However, the vase-life was not different to that of flowers held in similar concentrations of silver nitrate. All gerbera flowers held in SNP solutions showed significantly higher relative fresh weight than the control. Vase-life of gerbera flowers was extended by addition of either 50 or 100mgL−1 carvacrol and either 1 or 2mgL−1 SNP from 8.3 to 16d. In addition, the relative fresh weight and solution uptake of gerbera flowers were increased by addition of 100mgL−1 essential oils and 1 or 2mgL−1 SNP as compared to that of control flowers. Our results suggest the potential application of essential oils or SNP as novel alternatives to common chemicals used in preservative solutions for gerbera flowers. [Copyright &y& Elsevier]

Abstract: Genetic diversity was evaluated by RAPD markers and morpho-agronomic characters for a total of 42 accessions of Barberton daisy (Gerbera jamesonii) consisting of 29 commercial and 13 wild accessions. A total of 74 polymorphic bands were obtained employing a set of 12 primer pairs. The average genetic similarity coefficient for the 42 accessions, evaluated by Jaccard index was 0.55 ranging from 0.28 to 1.00. The genetic structure found among Barberton daisy accessions was evaluated by hierarchic classification analyses and UPGMA modeling, revealing six clusters of genotypes where two of them include the wild accessions and the remaining four including commercial material, except for wild genotype number 9. Shannon (H′) index was calculated using the molecular markers to investigate the genetic variation among the Gerbera accessions and showed higher values for the commercial cluster in comparison to the values obtained for the individuals from the non-commercial cluster, namely 0.34 versus 0.27, respectively. Therefore, both calculated indices (Jaccard and Shannon) indicated the presence of higher genetic variation among commercial accessions in comparison to the cluster representing non-commercial accessions, suggesting that genetic breeding programs may focus on commercial accessions to recombine interesting genotypes with commercially important and marketing-desired characteristics. [Copyright &y& Elsevier]

Abstract: Within the present study, a system for the automated harvest of Gerbera jamesonii pedicels with the help of image analytic methods was developed. The study can be divided mainly into two parts: the development of algorithms for the identification of pedicels in digital images and the development of procedures for harvesting these pedicels with a robot. Images of plants were taken with a stereo camera system, which consisted of two high-resolution CCD-cameras with near-infrared filters. The plant was positioned on a rotatable working desk and images of eight different positions were shot. The developed image processing algorithm segmented the potential pedicel regions in the images, removed noise, differentiated overlapping pedicels by using different algorithms and combined the remaining regions to pedicel objects. From the data of both images and eight plant positions three-dimensional models of the pedicels were created by triangulation. The remaining parts of the plants were modeled in a simple fashion. The evaluated 3D model is used to calculate spatial coordinates for the applied robot control. For harvesting the pedicels, an industrial robot with six axes (plus an additional linear axis) was used. A pneumatic harvest grabber was developed, which harvested the pedicels by cutting them off. In order to guarantee the collision free path of the robot, a path planning module was integrated, which includes the three-dimensional model of the plant and the test facility. With the applied techniques it was possible to correctly detect all pedicels on about 72% of the images. Regarding the whole image series of the respective plant, all pedicels could be detected in at least one photographing position in 97% of all cases. In the harvest experiments 80% of all pedicels could be harvested. The harvest rates decreased with increasing numbers of pedicels on a plant. Therefore, 98% of the pedicels could be harvested of plants with one or two pedicels, but only 51% were harvested of plants with five or more pedicels. In horticultural practice, an identification system for evaluating the stage of maturity should be included. An implementation for harvesting pedicels of different species with similar basic characteristics is imaginable. [Copyright &y& Elsevier]

• The use of calcium oxide nanoparticles in vase solutions has no precedent. • CaO-NP reduces stem bending of gerbera cut flower. • CaO-NP decreases weight loss, 6% up to 15 days. • CaO-NP applied in vase solutions maintains the postharvest quality of gerberas. • CaO-NP in vase solutions can be an alternative for conserving cut flowers. Gerbera flowers are positioned amongst the most marketed cut flowers worldwide due to their attractive appearance. Their shelf-life is typically short (7-12 days) owing to stem bending that determines its commercial value. Postharvest treatments based on vase solutions with calcium compounds (e. g., CaO, Ca (OH) 2 , CaCO 3 , CaCl 2) are applied to avoid stem bending. The aim of this research was to evaluate the effectiveness of vase solutions based on calcium oxide nanoparticles (CaO-NP) on the postharvest quality of gerbera (Gerbera jamesonii L. cv. 'Forza'). The treatments consisted in distilled water (negative control), 2000 mg·L−1 calcium chloride (positive control, CaCl 2 , 0.2 %), 0.1 % glycerol, and 50, 100 and 150 mg·L−1 of CaO-NP; glycerol (0.1 %) was applied to maintain the CaO-NP dispersed. Results indicated positive effects of CaO-NP on stem firmness, decreasing stem bending, as well as reducing the weight loss and preserving the diameter of the gerbera flowers. Moreover, gerberas treated with CaO-NP preserved their visual quality, and chlorophylls content. The action of CaO-NP did not modify phenolic compounds and antioxidant capacity. Thus, the application of CaO-NP can be considered as an efficient alternative vase solution to preserve gerbera flowers during postharvest. [ABSTRACT FROM AUTHOR]

Abstract: True-to-type clonal fidelity is one of the most important pre-requisites in micropropagation of crop species. Genetic fidelity of in vitro raised 45 plants of gerbera (Gerbera jamesonii Bolus) derived from three different explants, viz., capitulum, leaf and shoot tips, was assessed by 32 ISSR markers, for their genetic stability. Out of 32 ISSR markers, 15 markers produced clear, distinct and scorable bands with an average of 5.47 bands per marker. The markers designed from AG motif amplified more number of bands. The markers anchored at 3′ ends produced high number of consistent bands than unanchored markers. Fifteen ISSR markers generated a total of 3773 bands, out of which 3770 were monomorphic among all the clones. The Jaccard''s similarity coefficient revealed that out of 45 clones derived from different explants, 44 were grouped into a single large cluster alongwith the mother plant with a similarity coefficient value of 1.00, whereas one clone (C38) remained ungrouped. The clones derived from capitulum and shoot tip explants did not show any genetic variation, whereas, one of the leaf-derived clones exhibited some degree of variation. [Copyright &y& Elsevier]

• We used silver nanoparticles and 8-HQC to increase the vase life of Gerbera flowers. • The use of silver nanoparticles and 8-HQC increased the shelf life of Gerbera flowers compared to the control treatment. • Simultaneous use of both Silver Nano Particle and 8-HQC had better effects on increasing the vase life of flowers than using either of these materials alone. • 200 mg L-1 8-HQS + 15 mg L-1 SNP with 6% sucrose treatment had the highest positive effect on improving the vase life of flowers. Gerbera is one of the cut flowers with short vase life. In this research, silver nanoparticles (SNP) (0, 5, 15, and 25 mg L−1) and 8-hydroxyquinoline citrate (8-HQC) (0, 100, 200, and 300 mg L−1) as pulse treatment for 24 h in combination with 6% sucrose were used in order to increase the quality and vase life of cut Gerbera 'Sunway' flowers. The results indicated that the vase life of cut flowers treated with 15 mg L−1 SNP plus 200 mg L−1 of 8-HQC and 6% sucrose was higher than the other treatments (20.68 days). Fresh weight and water uptake of Gerberas were relatively higher than other treatments, and also, this treatment resulted in less protein degradation and lower malondialdehyde, higher carotenoid pigmentation. Treatment with 200 mg L−1 of 8-HQC and 6% sucrose and 15 mg L−1 SNP with 6% sucrose separately showed higher SOD activity than other treatments. The use of nanoparticles and 8- HQC in combination with sucrose in the preservative solution showed the best treatment in delaying senescence and increased the life of cut Gerbera flowers compared to other treatments (Distilled water and sucrose solution). [ABSTRACT FROM AUTHOR]

Abstract: An unique procedure for the mass shoot propagation of Gerbera using receptacle transverse thin cell layer (tTCL) culture procedure was developed. Genotype, flower bud age, explant size, position of receptacle tTCLs and culture media were found to affect the success of culture. Ten interspecific crosses of Gerbera showed different shoot regeneration rates and callus induction via receptacle tTCL culture, all of which had shoot regeneration rates higher than 57%. Flower buds collected on the 10th day resulted in 91% shoot regeneration after 6 weeks of culture on basal MS medium [Murashige, T., Skoog, F., 1962. A revised medium for rapid growth and bioassay with tobacco tissue cultures. Physiol. Plant. 15, 475–497] supplemented with 0.02mgl−1 thidiazuron (TDZ), 0.8mgl−1 adenine and 10% (v/v) coconut water (CW). This was significantly higher than those from flower buds on the 7th and 14th days (22% and 54%), respectively. Shoot regeneration rate was the highest (94–100%) in the middle layers of the receptacle. For mass shoot propagation, shoot clusters were subcultured on half-strength MS medium supplemented with 0.5mgl−1 indole-3-butyric acid (IBA), 0.5mgl−1 6-benzyladenine (BA) and 2.0mgl−1 kinetin after every 4 weeks. Plantlets formed when single shoots were cultured on half-strength MS medium containing 1mgl−1 IBA. All plantlets acclimatized well in the greenhouse. [Copyright &y& Elsevier]

Abstract: To investigate the responses of leaf photosynthesis and plant growth to a moving lighting system, potted gerberas (Gerbera jamesonii H. Bolus ex J.D. Hook “Festival”) were grown under supplemental lighting in a greenhouse with either a stationary or a moving lighting system positioned above the benches. The stationary system consisted of a fixed high pressure sodium (HPS) lighting system, while the moving lighting system consisted of a moving HPS fixture attached to a cable system to move the light fixture back and forth over the crop. In both cases, the supplemental lighting was applied from 6:00 to 24:00h with the same supplemental daily light integral (4.9molm−2 day−1). Moving lamps significantly increased leaf photosynthetic capacity as represented by light saturated net CO2 exchange rate (NCER) (A sat), light- and CO2-saturated rate of NCER (A max), maximum rate of Rubisco carboxylation (V cmax), maximum rate of electron transport (J max) and rate of triose phosphate utilization. However, in situ leaf NCER and stomatal conductance, leaf chlorophyll content index, leaf area, leaf thickness, fresh weight of plants were significantly lower under moving lighting than under stationary lighting. It is suggested that the reduced growth of plants under moving lighting might be due to (1) the overall lower light use efficiency of leaves under moving lighting than those under stationary lighting; (2) the slower response time of the photosynthetic system compared to the rate of change in light intensity under moving lighting. [Copyright &y& Elsevier]

In two separate trials during 2000–2002, the efficacy of slow sand filtration and UV treatment in eliminating Phytophthora cryptogea propagules, artificially added in the recirculating nutrient solution, was evaluated with gerbera plants grown in closed soilless systems. A slow sand filtration technique was tested both alone and in combination with different antagonistic strains belonging to Fusarium spp. and Trichoderma spp., isolated from gerbera rhizosphere and applied into the soilless system. The dynamics of these fungi in the recirculating nutrient solution and in the sand filter was also investigated by plate counts on selective media. Slow sand filtration and UV treatment were both effective in reducing P. cryptogea root rot. However, slow sand filtration may be a more feasible disinfection method than UV because of lower costs of installation and maintenance and for its adaptability to a wide range of production systems. Moreover, this disinfection technique can be successfully combine with the application of antagonistic microorganisms. [Copyright &y& Elsevier]

The effects of recycling the drainage solution by adding nutrients to replenish it at three different K:(K+Ca+Mg) ratios (0.40, 0.48, 0.56, equivalent basis) on yield, flower quality and nutritional status of soilless-grown gerbera were investigated. The recycling treatments were compared also to a control with free drainage and a standard K:(K+Ca+Mg) equivalent ratio of 0.40 in the irrigation solution. The ratios between NH4 and total N, Ca and Mg, macronutrient anions, and micronutrients, were identical in all treatments when injecting concentrated solutions of fertilizers to prepare fresh nutrient solution, and similar to standard recommendations for open systems, regardless of recycling or not. Furthermore, the target electrical conductivity and pH in the irrigation solution were identical in all treatments.When the drainage solution was recycled, the highest yield was obtained with the highest K:(K+Ca+Mg) injection ratio. However, both the number of flowers per plant and the flower stem length were significantly lower in all recycling treatments compared to those obtained when the effluents were discharged. This was attributed to a profound decline of the NH4 concentration in the drainage solution and, thus, also in the irrigation solutions prepared by reusing it, which resulted in increased pH in the root environment and restricted supply of Mn to the plants. In addition to Mn, the leaf P and Fe concentrations were also reduced by the increased pH in the root zone when recycling was applied. Hence, to prevent nutrient imbalances in closed hydroponic systems, it is suggested to supply potassium and nitrogen at higher K:(K+Ca+Mg) and NH4/total-N ratios than those recommended for open systems. [Copyright &y& Elsevier]

• Successful induction of multiple pure tetraploids in gerbera daisy by applying colchicine to emerging seedlings using a new simple method. • Determined the genome sizes of diploid and tetraploid gerbera (5.22 and 10.41 pg/2C, respectively). • Induced tetraploidization increased gerbera flower size by 23 %. • Induced gerbera tetraploids showed good pollen stainability (75 %) and can be used as as a seed or pollen parent in interploidy crosses for triploid production. • Induced gerbera tetraploids were characterized by lower stomatal density, thicker leaves and thicker scapes, which may enhance gerbera tolerance to abiotic stresses. Cultivated gerbera (Gerbera hybrida ; Asteraceae) is an economically important flower worldwide. It is also used as a model plant for studying flower development and understanding biosynthesis of secondary metabolites. Genetic variation in cultivated gerbera is narrow; therefore, increased genetic variation is much needed for further improvement of gerbera. Polyploidization has played an extremely important role in the diversification, evolution, domestication and breeding of many plant species. In this study, tetraploids were induced by treating the apical meristems of gerbera seedlings with colchicine. The nuclear DNA content of tetraploid gerbera was increased to 10.41 pg/2C from 5.22 pg/2C. Induced tetraploids had larger, fewer stomata and wider, thicker leaves than diploids, resulting an increased leaf index. With tetraploidization, flower scapes became thicker, flowers were larger, ray florets became wider, and the center eye (composed of disc florets) was larger. Induced tetraploids showed lower but still high pollen stainability and are expected to be quite fertile and be able to serve as parents for production of triploids. Some of the morphological changes associated with induced tetraploidy, including larger flowers, thicker ray florets, larger eyes and/or thicker scapes, will be beneficial for gerbera flower quality and vase life, while other changes such as stomatal size and density and thicker leaves may change and improve gerbera tolerance to stresses. Induced gerbera tetraploids may be valuable for breeding, genetic research and increasing genetic diversity in gerbera. [ABSTRACT FROM AUTHOR]

Abstract: The goal of this study was to evaluate the effect of cold cathode fluorescent lamps (CCFLs) on the growth of Gerbera jamesonii var. ‘Rui Kou’ plantlets in vitro in six different light quality ratios: 100% red CCFL (R), 80% R+20% blue CCFL (B), 70% R+30% B, 60% R+40% B, 100% B and white CCFLs (W). Control radiation was provided by conventional heat-generating plant growth fluorescent lamps (PGFLs). Plantlets under CCFLs showed better plantlet height, SPAD value (i.e., leaf chlorophyll content) and root activity (as assessed by root dehydrogenase activity) than those growing under PGFLs while all other growth parameters were comparable with plants under conventional lighting systems. [Copyright &y& Elsevier]

Gerbera, an important cut flower in the floriculture industry, is sensitive to early wilting and bent neck, which consequently reduce its postharvest vase life. To investigate the anti-bacterial properties of Tashenehdari (Scrophularia striata Boiss.), the effects of 0, 0.5, 1, 1.5, and 2% Tashenehdari extract were studied on the bacterial population, vase life, and physiochemical attributes of "Stanza" and "Pink Elegance" gerbera cut flowers. The results showed that bacterial populations increased with time in vase solutions and the stem ends of cut flowers, which drastically decreased flower quality. However, treatments significantly reduced the bacterial population and increased the vase life of gerbera cut flowers. The gram-positive bacteria were affected more rapidly compared to gram-negative bacteria by Tashenehdari extract. "Stanza" showed higher quality and longer vase life compared to "Pink Elegance". At ninth day postharvest, by increasing the concentration of Tashenehdari extract (from 0 to 2%), bacterial populations decreased in vase solutions and stem ends, along with electrolyte leakage (EL) of petals and stems, malondialdehyde (MDA), proline content, and polyphenol oxidase activity (PPO) https://www.ncbi.nlm.nih.gov/pubmed/15472151. Consequently, the vase life of cut flowers, relative fresh weight (RFW), vase solution uptake (VSU), total soluble solids (TSS), total phenol content, and the activities of catalase (CAT), peroxidase (POD), superoxide dismutase (SOD), and phenylalanine ammonia lyase (PAL) increased. Our results suggest that the antibacterial properties of Tashenehdari extract due to the presence of chlorogenic acid, catechin and quercetin compounds. Since the best results were obtained using 1.5 and 2% Tashenehdari extract, these treatments may be useful as a natural antibacterial solution in the storage and transportation of gerbera cut flowers. • Scrophularia striata Boiss.(Tashenehdari) is a member of Scrophulariaceae family with antibacterial properties. • Tashenehdari extracts decreased bacteria populations in vase solutions and stem ends of flowers. • Gram-positive bacteria were affected more rapidly compared to gram-negative bacteria. • Extract of 1.5% and 2% significantly controlled bacterial growth and caused vase life improvement in cut flowers. [ABSTRACT FROM AUTHOR]

• Gold nanoparticles are less toxic than silver nanoparticles to in vitro plant explants. • Silver nanoparticles inhibit rhizogenesis in chrysanthemum and gerbera. • Gold nanoparticles enhance root regeneration in gerbera. • Silver and gold nanoparticles improve the efficiency of Cape Primrose micropropagation. • Silver nanoparticles inhibit the formation of adventitious shoots in chrysanthemum. Despite an increasing interest in nanoparticles influence on plant metabolism and growth is recently observed, still it is an under-explored area of research, especially in the context of nanoparticles impact on the in vitro adventitious organogenesis in ornamental plants. The work presents the results of three independent experiments, in which silver and gold nanoparticles, 20 nm-in-size, were poured on the culture medium immediately after explants inoculation. The aim of the Experiment 1 was to evaluate the effect of 10 and 30 ppm silver and gold nanoparticles on the adventitious roots regeneration in Chrysanthemum × grandiflorum (Ramat.) Kitam. 'Bydgoszczanka' and Gerbera × jamesonii H. Bol 'Suri'. Chrysanthemum shoot fragments and gerbera single rosettes were polarly inoculated on the modified MS medium with 2 mg∙L−1 indole-3-acetic acid (IAA) for rooting. Chrysanthemum explants treated with 10 and 30 ppm silver nanoparticles regenerated less adventitious roots than control explants. These roots were also of the smallest area and diameter, but the length of the longest root was the highest in the experiment. Roots parameters after gold nanoparticles treatment were similar to those reported for the control object, expect for one parameter – the biggest values of root diameter (for 10 and 30 ppm). As for gerbera, the efficiency of adventitious roots regeneration was also reduced by 10 and 30 ppm silver nanoparticles, but the addition of 10 ppm gold nanoparticles stimulated rhizogenesis. Similarly to chrysanthemum, the greatest length of the longest root, the smallest root system area and root diameter were also observed under the influence of silver nanoparticles. In the Experiment 2 the effect of 10 and 30 ppm silver and gold nanoparticles on the adventitious shoots regeneration in Streptocarpus × hybridus Voss. was tested. Leaf explants were horizontally inoculated on the modified MS medium with 0.1 mg∙L−1 1-naphthaleneacetic acid (NAA). The best effects in the stimulation of the rosulate and phyllomorphs regeneration were reported for both silver and gold nanoparticles at the concentration of 10 ppm. The aim of the Experiment 3 was to evaluate the effect of 50 and 100 ppm silver nanoparticles on the adventitious shoots regeneration in Chrysanthemum × grandiflorum (Ramat.) Kitam. 'Lilac Wonder' and 'Richmond'. Internodes used as explants were horizontally put onto the modified MS medium with 0.6 mg∙L−1 BAP (benzylaminopurine) and 2 mg∙L−1 IAA. Formation of adventitious shoots was inhibited as a result of silver nanoparticles application at high concentrations. [ABSTRACT FROM AUTHOR]