Hydrangea Species Research Articles

Differential gene expression in leaves and roots of Hydrangea serrata treated with aluminium chloride.

Hydrangea serrata, also knowen as the Japanese tea hortensia, is known for its sweet taste and health properties of bevarages produced from this plant. The H. serrata 3,4-dihydroisocoumarins, hydrangenol and phyllodulcin harbour a variety of biological activities and pharmacological properties. Therefore, a detailed understanding of dihydroisocoumarin biosynthesis in H. serrata is of major interest. Their biosynthesis is assumed to be enhanced by elicitors and mediated by polyketide synthases like in cases of phenylpropanoid derived phytoalexins. A de-novo transcriptome assembly of leaves and roots from the aluminium chloride treatment group versus the control group alongside with annotation was generated. Secondary plant metabolites were analysed by LC-MS. It revealed that a terpene synthase and a triterpenoid synthase gene as well as lignin biosynthesis encoding genes were upregulated in roots. Many genes for transporters, glycosyl, and other transferases as well as glycosylases were found to be differentially expressed in both organs. As no differentially expressed polyketide synthase gene homolog was found, the relative leaf and root 3,4-dihydroisocoumarin content was analysed by LC-MS measurement. Although Hydrangea species are known for their aluminium detoxification using phenylpropanoid-derived compounds, the levels of 3,4- dihydroisocoumarins were not enhanced. In this metabolite analysis, an organ- specific accumulation profile of hydrangenol, phyllodulcin, hydrangeic acid and their mono- and di-glycosides was figured out.

From macro to micro: A close-up look at Hydrangea luteovenosa and Hydrangea serrata.

Understanding the anatomical traits of the foliar epidermis is essential for making precise species identification and categorization. In this study, scanning electron microscopy (SEM) was used to examine the taxonomically significant foliar epidermal traits of Hydrangea luteovenosa and H. serrata. The qualitative and quantitative traits observed included the epidermal cell form, cuticle presence, trichome morphology, stomatal type, and guard cell features. H. serrata had a thin and smooth cuticle, and epidermal cells organized compactly into cubic or hexagonal shapes. The stomata were of the anomocytic type and dispersed, while the trichomes were straightforward, unbranched, and distributed sparsely. The guard cells had distinct cell walls and a kidney-shaped morphology. These crucial traits for taxonomy were in line with an epidermis composed of three to five layers. Similar polygonal epidermal cells with a compact arrangement were observed in H. luteovenosa, together with a thin and smooth cuticle. The stomata were anomocytic and dispersed, while the trichomes were straightforward, unbranched, and sparsely distributed. The guard cells have distinct cell walls and a kidney-shaped morphology. The traits were indicative of an epidermal structure with three to five layers. These traits helped correctly identify and categorize these two species of Hydrangea. In addition to assisting in the taxonomic classification of these species and advancing knowledge of their ecological and evolutionary links, the SEM study provided insightful information into the structural variety of these species. RESEARCH HIGHLIGHTS: Microscopic characteristics of H. luteovenosa and H. serrata Understanding the anatomical traits of the foliar epidermis is essential for precise species identification and categorization.

First Report of Leaf Spot and Stem Rot Caused by Diaporthe eres on Hydrangea macrophylla in Italy

HomePlant DiseaseAhead of PrintFirst Report of Leaf Spot and Stem Rot Caused by Diaporthe eres on Hydrangea macrophylla in Italy PreviousNext DISEASE NOTE OPENOpen Access licenseFirst Report of Leaf Spot and Stem Rot Caused by Diaporthe eres on Hydrangea macrophylla in ItalyA. Garibaldi, G. Tabone, I. Luongo, and M. L. GullinoA. GaribaldiCentre of Competence AGROINNOVA, University of Torino, 10095 Grugliasco, ItalySearch for more papers by this author, G. TaboneCentre of Competence AGROINNOVA, University of Torino, 10095 Grugliasco, ItalySearch for more papers by this author, I. LuongoCentre of Competence AGROINNOVA, University of Torino, 10095 Grugliasco, ItalySearch for more papers by this author, and M. L. Gullino†Corresponding author: M. L. Gullino; E-mail Address: [email protected]https://orcid.org/0000-0002-7706-1915Centre of Competence AGROINNOVA, University of Torino, 10095 Grugliasco, ItalySearch for more papers by this authorAffiliationsAuthors and Affiliations A. Garibaldi G. Tabone I. Luongo M. L. Gullino † Centre of Competence AGROINNOVA, University of Torino, 10095 Grugliasco, Italy Published Online:9 Jun 2023https://doi.org/10.1094/PDIS-08-22-1786-PDNAboutSectionsPDF ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat Native to the temperate and subtropical regions of Japan and China, Hydrangea macrophylla (big leaf hydrangea) is a shrubby plant in the Hydrangeaceae used to embellish parks, gardens, private terraces, and balconies. Punctiform brown leaf spots and stem necrosis appeared in the summer of 2021 on 10 of approximately 50 H. macrophylla plants. The 20-year-old plants were cultivated in pots and in mixed borders in a private garden located in Piedmont (Biella Province 45°36′00″N, 8°03′00″E). Spots enlarged to encompass the entire surface; eventually affected leaves abscised. Affected leaves at the early stage of disease were randomly collected and fragments, obtained from the margins of necrotic tissues, were disinfected in 1% sodium hypochlorite, rinsed in sterilized water, and distributed on potato dextrose agar (PDA) amended with 25 mg/liter of streptomycin sulfate. Plates were maintained at room temperature (22 to 26°C) and colonies, characterized by white, aerial, fluffy mycelium with a dark pigmentation at the center, appeared after 5 days. Mycelium of one representative pure culture grown on PDA for 20 days became gray with age and developed dark brown pycnidia and black stromata at maturity. Alpha conidia were hyaline, aseptate, fusiform to ellipsoidal, often biguttulate, and 5.1 to 10.2 (average 7.2) × 1.9 to 3.7 (average 3.0) μm (n = 50). Beta conidia were hyaline, aseptate, linear to curved, and 14.5 to 35.7 (average 24.9) × 0.6 to 2.9 (average 1.6) μm (n = 50). These morphological characteristics permitted identification of the fungus as Diaporthe sp. (Gomes et al. 2013). Polymerase chain reaction (PCR) and Sanger sequencing was carried out for ITS, calmodulin (cal) (Cal228F/Cal2Rd), tef1 (EF1-728/EF1-986R), and tub2 (T1/Bt2b) (Udayanga et al. 2014) of the representative isolate 22/12-1 (GenBank accessions OP080713, OP700046, OP14610, and OP700047, respectively). Sequences analyzed with BLASTn (Altschul et al. 1997) showed 99.5% identity for ITS (567/570 bp; KC343097), 99.8% for cal (414/415 bp; KC343339), 100% for tef1 (347/347 bp; KC343823), and 100% for tub2 (690/690 bp; KC344065) with sequences from strain CBS 841.84 of Diaporthe eres. Pathogenicity of the isolate 22/12-1 was verified by performing a pathogenicity test on five healthy 20-year-old H. macrophylla plants grown in pots and in borders. A conidial suspension at a concentration of 1 × 105 conidia/ml, obtained from a pure culture of the isolate grown for 20 days on potato dextrose agar (PDA), was sprayed on the leaves of the H. macrophylla plants (5 ml/plant). Three noninoculated plants sprayed with sterile deionized water were used as a control. Plants were covered with a transparent plastic bag and maintained in the garden at a temperature of 24 to 36°C. Leaf spots and stem necrosis developed on the inoculated plants after 7 to 10 days. Colonies with the same morphological characteristics of the original isolate were isolated from the margins of the necrotic leaf tissue. The pathogenicity test was repeated once, obtaining the same results. D. eres was previously reported on several species of Hydrangea (Farr and Rossman 2022). To our knowledge this is the first report of D. eres on H. macrophylla in Italy. Diaporthe (syn. Phomopsis) is the causal agent of severe disease and could represent a serious problem for the cultivation of H. macrophylla in gardens and a reduction of the ornamental value.The author(s) declare no conflict of interest.

Extensive characterization of 28 complete chloroplast genomes of Hydrangea species: A perspective view of their organization and phylogenetic and evolutionary relationships

The tribe Hydrangeeae displays a unique, distinctive disjunct distribution encompassing East Asia, North America and Hawaii. Despite its complex trait variations and polyphyletic nature, comprehensive phylogenomic and biogeographical studies on this tribe have been lacking. To address this gap, we sequenced and characterized 28 plastomes of Hydrangeeae. Our study highlights the highly conserved nature of Hydrangeaceae chloroplast (cp) genomes in terms of gene content and arrangement. Notably, synapomorphic characteristics of tandem repeats in the conserved domain of accD were observed in the Macrophyllae, Chinenses, and Dichroa sections within the Hydrangeeae tribe. Additionally, we found lower expression of accD in these sections using structure prediction and quantitative real-time PCR analysis. Phylogenomic analyses revealed the subdivision of the Hydrangeeae tribe into two clades with robust support values. Consistent with polyphyletic relationships, sect. Broussaisia was identified as the basal group in the tribe Hydrangeeae. Our study also provides insights into the phylogenetic relationships of Hydrangea petiolaris in the Jeju and Ulleung Island populations, suggesting the need for further studies with more samples and molecular data. Divergence time estimation and biogeographical analyses suggested that the common ancestors of the tribe Hydrangeeae likely originated from North America and East Asia during the Paleocene period via the Bering Land Bridge, potentially facilitating migration within the tribe between these regions. In conclusion, this study enhances our understanding of the evolutionary history and biogeography of the tribe Hydrangeeae, shedding light on the dispersal patterns and origins of this intriguing plant group with its unique disjunct distribution.

Comprehensive Metabolite Profiling of Hydrangea macrophylla ssp. serrata Extracts Using Liquid Chromatography Coupled with Electrospray Ionization Ion Mobility Quadrupole Time-of-Flight Mass Spectrometry.

A wide range of secondary metabolites has been described for various Hydrangea species, including the sweet-tasting phenyldihydroisocoumarin phyllodulcin, which is found in the leaves of Hydrangea macrophylla ssp. serrata. This work aims at the development and validation of an analytical workflow for comprehensive semi-polar metabolite profiling using liquid chromatography coupled with electrospray ionization ion mobility quadrupole time-of-flight mass spectrometry (UPLC-ESI-IMS-QToF-MS) to complement existing analytical studies. The unsupervised analysis of this data set demonstrates the capability of this analytical workflow to distinguish different H. macrophylla ssp. serrata cultivars. In combination with supervised analysis, a list of metabolites responsible for the differentiation of the cultivars studied has been obtained. Suspect screening of phenyldihydroisocoumarins provides comprehensive information, which could help in the search for key enzymes related to the biosynthesis of phyllodulcin.

Physiological and metabolomics responses of Hydrangea macrophylla (Thunb.) Ser. and Hydrangea strigosa Rehd. to lead exposure

Hydrangea is a potential remediation plant for lead (Pb) pollution. Plant roots communicate with soil through the release of root exudates. It is crucial to study rhizoremediation mechanisms to understand the response of root exudates to contamination stress. Here, we investigated the physiological responses and metabolomic profiling of two Hydrangea species, a horticultural cultivar (Hydrangea macrophylla (Thunb.) Ser.) and a wild type (Hydrangea strigosa Rehd.), under Pb-free and Pb-stressed conditions for 50 days. The results showed that Pb treatment adversely affected the biomass and root growth of the two species. H. strigosa was a Pb-tolerant species with higher superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) activities and more ascorbic acid (AsA) content in roots. Metabolomic profiling showed that 181 and 169 compounds were identified in H. macrophylla and H. strigosa root exudates, respectively, among which 18 showed significant differences between H. macrophylla and H. strigosa under Pb exposure. H. strigosa showed significantly (P < 0.05) higher secretion of sucrose, glycolic acid, and nonanoic acid than H. macrophylla after Pb treatment. Pb stress promoted fatty acid metabolism in H. strigosa, suppressed amino acid metabolism in H. macrophylla, and promoted a higher carbohydrate metabolism in H. strigosa compared with H. macrophylla. This study provides a possible mechanism for the high Pb absorption potential of Hydrangea.

First Report of Golovinomyces orontii Causing Hydrangea macrophylla Powdery Mildew in Qinghai-Tibet Plateau, China.

Hydrangea macrophylla (Thunb.) Ser. (Hydrangeaceae) is the most popular hydrangea species grown in home gardens and landscapes in China. Plants of H. macrophylla with symptoms of powdery mildew were found in a commercial wholesale nursery in Huzhu, Haidong (36°49'11.87" N, 101°57'03.36″E, alt. 2490 m), in May 2020, with disease incidence reaching 80%. Symptoms included yellowing and necrosis of leaves. Upon microscopic observation, masses of conidia and mycelium were observed covering the symptomatic tissues. Fungal isolates displayed nipple-shaped hyphal appressoria, often poorly developed, conidiophores erect, arising laterally or from the upper surface of hyphal mother cells, and positioned almost centrally or towards one end of the cells, up to about 160 μm long (n = 30), with foot cells straight or flexuous, 32 to 86 × 8 to 13 μm (n = 50), followed by one to three shorter cells about 11 to 24 × 10 to 15 μm (n = 50), forming catenescent conidia in usually predominantly chains, conidia doliiform to limoniform, hyaline, 24 to 35 × 13 to 25μm (n = 50). Conidial germination was of the Euoidium type. Chasmothecia were not observed. To confirm fungal classification, single spores were isolated and cultured on detached leaf bioassay following the protocol described in Farinas et al. (2019). Total DNA was extracted directly from single-spore cultures using a Chelex extraction method (Walsh et al. 1991). The rDNA internal transcribed spacer (ITS) regions were amplified by polymerase chain reaction (PCR) utilizing the universal primer pairs ITS1/ITS4 (White et al. 1990). The sequences (726-727 bp) were deposited in GenBank (accessions no. MT568633, MT757924 and MT757925). The ITS sequences showed 99.9-100% identity with a sequence of Golovinomyces orontii reported on Papaver rhoeas (AB769466) in Switzerland. Based on the ITS rDNA phylogenetic tree, the sequences retrieved from the specimen clustered within a strongly supported clade with G. orontii (AB769466), confirming the identity of the pathogen (Takamatsu 2013). Cladistic trees were constructed using the neighbor-joining method with the Kimura 2-parameter substitution model in MEGA 6.0. Branch robustness was assessed via bootstrap analysis with 1,000 replicates. To confirm pathogenicity, eight H. macrophylla plants were sprayed until run-off with a suspension containing 1 × 105 conidia/ml. Four plants were used for fulfilling Koch's postulates and four plants were used as mock-inoculated controls sprayed only with sterile distilled water. Inoculated and non-inoculated plants were covered with plastic bags separately and maintained overnight in a greenhouse at 25 ± 2°C and 50 to 60% relative humidity. Typical powdery mildew colonies developed on inoculated plants 10 to 15 days after inoculation, which were morphologically identical to those originally observed on the diseased plats, whereas the control plants remained symptomless. To our knowledge, this is the first report of powdery mildew caused by G. orontii on H. macrophylla in Qinghai-Tibet Plateau, China (Braun and Cook 2012).

Early Ontogeny of Introduced Hydrangea Species

Early Ontogeny of Introduced Hydrangea Species

On Hydrangea peruviana, an endangered species from Ecuador, and Hydrangea oerstedii, very common in Costa Rica and Panama, and seven threatened Central and South American Hydrangeas, which have been confounded with these.

Hydrangea section Cornidia, currently consisting of 19 accepted taxa, occurs from Mexico to Chile and Argentina, with one species in southeast Asia. Its representatives are root-climbing lianas which may grow up to 60 m high in the tree canopy of temperate to (sub)tropical forests. Our extensive field work throughout its distribution area, study of herbarium specimens and ongoing molecular studies have resulted in the discovery of species new to science, as well as new insights into the circumscription of many taxa. We here present amended descriptions for seven Hydrangea species of Central and South America and discuss the taxonomical situation of two Colombian Hydrangeas, including an identification key, illustrations, and distribution maps. Field work was carried out in Costa Rica, Panama, Ecuador and Peru, including exploration in areas where the genus had not been collected before. These specimens and observations were complemented with the study of specimens of 41 herbaria of North, Central and South America, as well as Europe. Detailed morphological studies of all species were carried out, based on living plants in their natural habitat, as well as on dried specimens from our own collections and all available herbarium material. Type material was studied in detail for all species concerned. Based on an extensive number of morphological characters, combined with distribution patterns, phenological differences and ecological preferences, including molecular data in most cases, Hydrangea peruviana and H. oerstedii are clearly distinct taxa, as well as the other seven species mentioned here, which had been synonymized with either of these two species. The present study results in the recognition of 26 species in section Cornidia and exemplifies the urgent need for profound taxonomic studies in plants, as in many families we do not dispose of well-circumscribed units for conservation to mitigate the already occurring unprecedented loss of biodiversity.

The study of the genus &lt;i&gt;Hydrangea&lt;/i&gt; L. representatives reproduction by cuttings in various environmental conditions in the Republic of Bashkortostan

The paper deals with the study results of the Hydrangea species reproduction by green and lignified cuttings based on the collection of the South-Ural Botanical Garden-Institute of the Ufa Federal Research Centre of the Russian Academy of Sciences. The purpose of the work is to study the reproduction by cuttings of species and varieties of the genus Hydrangea and to identify optimal environmental conditions for the most effective result of cuttings. During the experiments green cuttings were rooted in 5 different types of substrates (sand, peat, a mixture of sand and peat, a mixture of sand and perlite, a mixture of peat and perlite). As rooting stimulants Kornevin and Heteroauxin were used. The reproduction of Hydrangea by lignified cuttings was studied after various storage methods during winter. It was found that the maximum rooting percentage is obtained when peat is used as a substrate (rooting reaches 96,7%). The maximum root-forming ability when reproduced by green cuttings using rooting stimulants (Kornevin and Heteroauxin) was observed in H. arborescens (86,6-93,3%) and its varieties (79,8-96,5%). High results were obtained when tree hydrangea was reproduced by both green and lignified cuttings. The root-forming ability of lignified cuttings increases when they are stored during winter under snow.

South and Central America Cut Flower Production and Postharvest Survey

Imports of cut flowers into the United States have doubled in the last 20 years and come mainly from Colombia and Ecuador. We surveyed the cut flower industry in South and Central America, focusing on Colombia and Ecuador, to determine their production and postharvest problems. We received a total of 51 responses, of which 62% of the respondents had 100 or more employees. The most commonly grown or handled crops were rose (Rosa hybrids), carnation (Dianthus caryophyllus), chrysanthemum (Chrysanthemum ×grandiflorum), alstroemeria (Alstroemeria cultivars), gerbera (Gerbera jamesonii), and hydrangea (Hydrangea species), in order of ranking. The most significant production problem was insect management, with disease management and crop timing the next most important issues. The most important species-specific issues in production were phytosanitary problems, disease (causal organism not specified), leaf miner (Lepidoptera, Symphyta, or Diptera), and thrips (Thysanoptera). The main overall postharvest problem was temperature management, followed by hydration and flower food management and botrytis (Botrytis cinerea). In regard to on-farm postharvest handling, damage to the flowers was the most mentioned issue. For the postharvest during storage and transport phase, temperature management, air transport, damage, and botrytis were the most important problems. The most mentioned customer complaints were damage, botrytis, and phytosanitary problems. The results of this survey can be used by researchers to focus their work on topics of most need. Improved production and postharvest handling will support the continued growth of the cut flower industry.

Pollination-related functions of decorative sterile flowers of nine JapaneseHydrangeaspecies (Hydrangeaceae)

Most species of Hydrangea (Hydrangeaceae) have a flower arrangement in which several large sterile decorative flowers surround a dense cluster of small fertile flowers. These decorative flowers have been hypothesized to attract pollinators, but this has yet to be tested for this genus. To identify whether the decorative flowers have functions related to pollination success, we carried out field manipulation experiments in which we clipped or mounted decorative flowers of nine Hydrangea species, eight with and one without inherent decorative flowers, and recorded insect visits to the intact and treated inflorescences. The results showed that for most of the studied species, the presence of decorative flowers increased the frequency of visits and weakly increased the frequency of visits per unit area to inflorescences. Decorative flowers appeared to act as landing-sites for three species for which flowers represented a high proportion of the inflorescence surface area (i.e., H. scandens, H. luteovenosa, and H. macrophylla). The results suggest that the main function of decorative flowers of the studied Hydrangea species is to boost attractiveness to pollinators by increasing the inflorescence surface area, whereas the landing-site function was evident only in certain species.

Las Hydrangeas trepadoras (Hydrangeaceae) de México, incluyendo la descripción de seis nuevas especies en peligro (crítico)

Antecedentes y Objetivos: El género Hydrangea consta de aproximadamente 200 taxones en Asia y América. Mientras que las especies arbustivas de Asia y los EUA, así como los más de 1000 híbridos y cultivares derivados de estos, son muy conocidos por su valor ornamental, las especies neotropicales son mucho menos apreciadas. Hydrangea sección Cornidia, con 13 taxones aceptados, se distribuye desde México hasta Chile y Argentina, con una especie en el sureste de Asia. Sus representantes son lianas trepadoras que pueden crecer hasta 60 m de altura en el dosel de árboles de bosques templados a selvas (sub)tropicales. Extenso trabajo de campo a lo largo de su área de distribución y estudio de especímenes de herbario ha resultado en el descubrimiento de nuevos taxones. Presentamos una revisión de las diez especies mexicanas actualmente conocidas.Métodos: Se llevó a cabo trabajo de campo en el noroeste, centro y sureste de México, incluida la exploración en áreas donde el género no se había recolectado anteriormente. Se llevaron a cabo estudios morfológicos y arquitectónicos detallados, basados en plantas vivas en su hábitat natural, así como en muestras secas de nuestras colecciones y el material de herbario disponible.Resultados clave: Se describen seis especies nuevas para la ciencia, incluyendo una clave de identificación para las nativas y una ampliamente cultivada, ilustraciones y mapas de distribución. Se presentan descripciones enmendadas para dos especies descritas anteriormente, por lo que todas las Hydrangeas mexicanas conocidas actualmente cuentan con una descripción morfológica detallada.Conclusiones: El género Hydrangea ejemplifica la falta de actividades de recolección botánica específicas de taxones en México. El descubrimiento de estas nuevas especies es aún más sorprendente teniendo en cuenta el tamaño considerable de estas plantas. Todas las especies mexicanas están amenazadas, principalmente debido a la deforestación y cambios en el uso del suelo.

Optimizing pollen germination and pollen viability estimates for Hydrangea macrophylla, Dichroa febrifuga, and their hybrids

The genus Hydrangea L. is comprised of some of the most popular ornamental plants in the world. The development of interspecific hybrids between Hydrangea species and within the family Hydrangeaceae would increase genetic diversity in the Hydrangea breeding pool and lead to unique combinations of desirable traits. Protocols to estimate Hydrangea pollen viability need to be optimized in order to perform basic studies on self- and cross-incompatibility, fertility of hybrids, formation of unreduced gametes, and pollen storage. Our goal is to quantify pollen production in Dichroa, Hydrangea, and their hybrids, determine the optimal media for pollen germination, and develop a series of correlations between staining and germinating that can be applied to stained pollen for a rapid, precise estimate of viability. Production of round versus oblong pollen grains was heavily influenced by species (F = 335.8, p < 0.001). Dichroa accessions produced an average of 86% round grains while Hydrangea accessions produced 65% round grains. Dichroa x Hydrangea hybrids averaged only 39% round grains. The optimal media composition for all accessions based on iterative test was 7.5% sucrose, 0.01% Ca(NO3)2, and 0.025% H3BO3, and 10 mM 2-(N-morpholino)ethanesulfonic acid pH 5.5. Aniline blue-lactophenol staining overestimated viability by an average of 2.3x for Hydrangea and Dichroa, and an average of 4.1x for hybrids as compared to in vitro germination. The results from this experiment will provide more consistent results within and between laboratories and will easily fit into existing Hydrangea breeding programs.

Occurrence of hydrangea ringspot virus and hydrangea chlorotic mottle virus in hydrangea plants in South Korea

Approximately 25 species of Hydrangea, often grown for cut flowers and landscaping, are widely distributed in Asia, the Americas, Europe, and South Africa and can be affected by multiple viruses. To identify any viruses affecting hydrangea populations in South Korea, we analyzed symptomatic samples from three different regions in South Korea using RT-PCR and sequenced the amplified products. From the 211 hydrangea plants sampled with virus-like symptoms such as chlorotic mottle, chlorotic and brown spots on the leaves and distortion of leaves, hydrangea ringspot virus (HdRSV) was found in 33 plants, and hydrangea chlorotic mottle virus (HdCMV) was detected in 10; two plants were co-infected with HdRSV and HdCMV. The coat proteins of HdRSV and HdCMV had the greatest amino acid sequence homology to HdRSV Hyd-CZ (98.7 % identity, GenBank accession GQ265901) and HdCMV-US (97.9 % identity, GenBank accession DQ412999), respectively. To our knowledge, this study is the first report of HdRSV and HdCMV infection in hydrangea plants in South Korea.

등수국의 종자발아에 미치는 몇 가지 요인

Abstract - This study was carried out to establish seed propagation method of Hydrangea petiolaris Siebold & Zucc., one of the specific and protected plant species for the floral region. Seed size ranged 1.36 × 0.84 ㎜, weight of thousand seeds was 2.3 ± 0.02 ㎎. Observation of seed morphology characters showed wrinkled surface and elliptical shape, indicating amber color and fine seeds. Moisture contents of seeds, increased rapidly by water-soaking treatment, recording maximum moisture contents (31.9%) after 48 hours. Percent germination of seeds was higher under the light than dark condition. Seed germination was the best at 25 ℃ under the light condition (78.0%) among temperature and light conditions treated. Percent germination, germination energy and T 50 was greatly improved by soaking in GA 3 solutions for 48 hours. Especially, 100 ∼500 ㎎·L -1 GA 3 treatment resulted in the highest germination rate as 90.0% and above. Key words - GA 3 , Germination energy, Hydrangea species, Seed propagation, T

Quantitative and qualitative changes in carbohydrates associated with spring deacclimation in contrasting Hydrangea species

Cold deacclimation and associated changes in soluble carbohydrates and water status of two Hydrangea species differing in susceptibility to frost injuries was followed under natural conditions. In fully cold hardy plants of H. macrophylla stem freezing tolerance fluctuated in parallel with changes in air temperature, while in a seasonal perspective increased temperatures caused a sigmoid deacclimation pattern in both H. macrophylla and H. paniculata. Timing of deacclimation was approximately synchronized in the two species, but H. paniculata, the hardier species based on mid-winter hardiness, deacclimated faster than H. macrophylla, indicating that deacclimation kinetics were not correlated with mid-winter hardiness. In both species concentrations of soluble sugars decreased during deacclimation and were highly correlated with stem cold hardiness and air temperatures. This suggests that sugar hydrolysis may be an important temperature-driven mechanism of deacclimation in Hydrangea. Accumulation patterns of specific carbohydrates differed between the two species, suggesting that they utilize different strategies to overcome cold. In H. paniculata, deacclimation was associated with an increase in stem water content, which occurred shortly before bud burst and hence may be a prerequisite for leafing out.

Effects of chilling temperatures and short photoperiod on PSII function, sugar concentrations and xylem sap ABA concentrations in two Hydrangea species

Cold injuries are frequently seen in Hydrangea macrophylla but not in Hydrangea paniculata. This may be ascribed to different levels of hardiness in the non-acclimated and the acclimated state, and to differences in responses to short day (SD) and low temperature (LT) and hence in the ability to cold acclimate. In this study H. macrophylla ssp. macrophylla (Thunb.) Ser. ‘Blaumeise’ and H. paniculata Sieb. ‘Kyushu’ were exposed to short photoperiod (10-h) and 4 °C in controlled conditions for 25 days, with measurements and samplings carried out at regular intervals. Chlorophyll fluorescence measurements revealed significant alterations in O–J–I–P fluorescence kinetics and decreases in the photochemical efficiency of photosystem II in stressed plants, followed by less chlorophyll contents. Perturbations of the photosynthetic apparatus were relatively greater in H. macrophylla than in H. paniculata. Likewise, induction of a transient increase in xylem sap abscisic acid concentrations ([ABA] xylem) and accumulation of soluble sugars in leaves and stems were different in the two species. Stem cold hardiness in the non-acclimated state did not differ between H. macrophylla and H. paniculata, indicating equal sensitivity to sudden temperature drops in the growing season. Despite adaptive responses induced by the treatment neither species developed increased stem cold hardiness, suggesting that cold acclimation in Hydrangea may require exposure to temperatures below ca. 4 °C.

French Hydrangea for Gardens in North and Central Florida

ENH-1069, a 7-page illustrated fact sheet by Gary W. Knox, describes this widely grown species of hydrangea, its origin and development, reflowering cultivars, how to grow them in Florida gardens, flowering schedule, types, and characteristics, variations in flower colors, and pest management. Includes references. Published by the UF Department of Environmental Horticulture, April 2007. ENH1069/EP330: Bigleaf and Mountain Hydrangeas for Gardens in North and Central Florida (ufl.edu)

Genetic Diversity Estimates for the Genus Hydrangea and Development of a Molecular Key Based on SSR

Using 14 codominant microsatellite markers that amplify loci across 14 different Hydrangea L. species, we analyzed gene diversity and genetic similarity within Hydrangea. Samples also included Dichroa Lour., Platycrater Sieb. and Zucc., and Schizophragma Sieb. and Zucc. genera to establish their relatedness to Hydrangea species since previous work suggests they may be closely related. Our results support the close affiliation between Macrophyllae E.M. McClint. and Petalanthe (Maxim.) Rehder subsections and their separation from the other Hydrangea species. Most of the Hydrangea species analyzed cluster within their designated sections and subsections; however, genetic distance between species within each subsection varied considerably. Our data suggest that morphological analyses which labeled H. serrata (Thunb.) Ser. as a subspecies of H. macrophylla (Thunb. Ex J.A. Murr.) Ser. are probably more accurate than recent genome size data suggesting H. macrophylla ssp. macrophylla (Thunb.) Ser. and H. macrophylla ssp. serrata (Thunb.) Makino are separate species. Gene diversity estimates indicate that 64.7% of the total diversity is due to differences between species and 49.7% of the overall variation is due to differences between subsections. Low diversity suggests a lack of gene flow between species and subsections and underscores the difficulty in making wide hybrids. Since only 35.3% of the genetic variation is common to all species, unique alleles were used to develop a molecular key for unambiguous species identification and interspecific hybrid verification. Genetic similarity estimates for all 85 samples suggests a roadmap for introgressing horticulturally important traits from different Hydrangea species.