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Hydrangea macrophylla (Thunb.) Ser. is one of the widely cultivated plants in home gardens and scenic areas of China. Anthracnose disease is commonly observed during the normal growth of H. macrophylla , significantly impacting its ornamental and economic values. From 2021 to 2023, an investigation on H. macrophylla anthracnose was carried out in nine parks of Beijing, China, and a total of 114 Colletotrichum isolates were obtained from the diseased leaves with typical anthracnose symptoms. Based on morphological characteristics and phylogenetic analysis of six genomic loci including rDNA-ITS, ACT , TUB2 , CAL , CHS-1 , and GAPDH , these isolates were identified as belonging to six Colletotrichum species. Among which, C. gloeosporioides was the most abundant (65 isolates, 57.0%), followed by C. fructicola (33 isolates, 28.9%), C. aenigma (8 isolates, 7.0%), C. truncatum (4 isolates, 3.5%), C. subacidae (2 isolates, 1.8%) and C. sojae (2 isolates, 1.8%). Pathogenicity test conducted on detached leaves of H. macrophylla revealed a distinct variation in virulence among isolates from different Colletotrichum species, and wounding was either essential or conducive to successful infection. Specifically, C. gloeosporioides exhibited greater aggressiveness, resulting in larger lesions, while C. subacidae induced lesions most quickly. Fungicide sensitivity assays demonstrated that prochloraz exerted a remarkable inhibitory effect on the mycelial growth of representative isolates belonging to the three predominant Colletotrichum species. In contrast to difenoconazole and tebuconazole, the mean EC50 values for prochloraz against C. gloeosporioides , C. fructicola , and C. aenigma were 0.062, 0.033, and 0.023 μg/ml, respectively. This is the first report of C. aenigma , C. truncatum , C. subacidae and C. sojae causing H. macrophylla anthracnose worldwide including China. These findings have elucidated the Colletotrichum species associated with H. macrophylla anthracnose as well as their fungicides sensitivities in Beijing, China. This provides a scientific foundation for the accurate diagnosis and local management of H. macrophylla anthracnose. [ABSTRACT FROM AUTHOR]

Abstract Background Bigleaf hydrangea (Hydrangea macrophylla) is a widely cultivated ornamental plant species. Leaf spot disease, caused by Corynespora cassiicola, poses a significant threat to the ornamental quality and economic value of hydrangeas. However, the disease resistance breeding of hydrangea is limited due to the lacking of resistant varieties and genes. Results This study evaluated ten hydrangea varieties for their resistance to leaf spot disease. Among them, ‘White Angel’ and ‘Ocean Heart’ were screened out as representative varieties for resistance and susceptibility, respectively, on the basis of evaluation. Physiological and biochemical indices, phytohormones, and transcriptomic changes were measured in the leaves of both varieties at 0 and 24 h post inoculation with C. cassiicola. The results showed that C. cassiicola infection significantly increased abscisic acid (ABA) contents in both varieties; however, the increase was significantly higher in the susceptible variety ‘Ocean Heart’ compared to the resistant variety ‘White Angel’ (p

Hydrangea macrophylla, renowned for its large inflorescences and a diverse range of colors, highlights a significant limitation in current gene function research, which is the lack of effective molecular genetic tools. This study utilized a tobacco rattle virus (TRV)-based virus-induced gene silencing (VIGS) system to investigate gene function through posttranscriptional gene silencing in H. macrophylla for the first time. The ortholog of phytoene desaturase (PDS) in H. macrophylla, termed HmPDS, was identified. Infection of tissue-cultured seedlings with TRV-HmPDS led to photobleaching of the leaves. Additionally, infection with TRV containing the HmCHS1 fragment in the flowers resulted in decreased anthocyanin production in sepals and a lightening of sepal coloration in the infected flowers. The phenomena and RT-qPCR results proved that the PDS and CHS genes of hydrangea were successfully silenced via the vacuum infiltration method. Furthermore, the introduction of TRV-HmF3′5′H revealed a decrease in delphinidin-3-glucoside content in sepals and caused a color change in the sepals from blue to pink. This study demonstrated that the TRV-VIGS system was successfully established in H. macrophylla and effectively applied to the function analysis of HmF3′5′H. [ABSTRACT FROM AUTHOR]

Hydrangea macrophylla (H. macrophylla), a species in the genus Hydrangea in the family Hydrangeaceae, is widely valued for its ornamental qualities in both domestic and international markets. Notably, H. macrophylla is known for its ability to accumulate aluminum (Al). Moreover, aluminum ions (Al3+) participate in sepal bluing. However, the underlying mechanisms of Al accumulation in the sepals remain unclear. In this study, we utilized transcriptome data from two cultivars to identify genes associated with Al accumulation. In total, 154 differentially expressed isoforms between the CK and Tr groups in the sepals of both cultivars were screened. Through gene enrichment analysis and similarity identification in the CDS (coding sequence) region, 43 differentially expressed genes were identified, including 30 upregulated and 13 downregulated genes, in the sepals of the Al treatment group. Further analysis revealed that seven of these upregulated genes are related to Al accumulation in sepals. Among the seven, the gene HmALS3.1 was identified as a potential key player in Al transport within the sepals of H. macrophylla. This study lays the groundwork for further exploration into the mechanisms by which HmALS3.1 regulates Al accumulation in H. macrophylla. [ABSTRACT FROM AUTHOR]

Steel slag is an industrial solid waste produced during the steelmaking process. To explore the application of steel slag in the agricultural field, the present experiment was carried out to study the effect of substrates with different contents of steel slag on the growth of Hydrangea macrophylla cuttings. The conventional substrate (perlite: vermiculite: peat = 1:1:1) was used as the control (CK), and the treatments were designed as T1 (steel slag: perlite: vermiculite: peat = 1:3:3:3, v/v/v/v), T2 (steel slag: perlite: vermiculite: peat = 1:2:2:2, v/v/v/v), T3 (steel slag: perlite: vermiculite: peat = 1:1:1:1, v/v/v/v), and T4 (steel slag: perlite: vermiculite: peat = 1:0:0:0, v/v/v/v). The results showed that the addition of steel slag significantly increased the substrate's bulk density, EC, and pH and improved its water retention capacity to a certain extent. There were significant differences among different treatments in morphological indicators, root growth and development, and physiological and biochemical characteristics of cutting seedlings. All traits, including plant height, fresh weight, dry weight, root length, root surface area, root volume, the number of root tips, root activity, and soluble protein content of seedlings grown in T3 were significantly higher than those in other substrates. The results indicated that the appropriate addition of steel slag is helpful to hydrangea cuttings' growth, and the optimal mixing ratio is steel slag: perlite: vermiculite: peat = 1:1:1:1 (v/v/v/v). This is a significant innovation in applying steel slag in agricultural production. [ABSTRACT FROM AUTHOR]

Hydrangea macrophylla (Thunb.) Ser. is one of the widely cultivated plants in home gardens and scenic areas of China. Anthracnose disease is commonly observed during the normal growth of H. macrophylla, significantly impacting its ornamental and economic values. From 2021 to 2023, an investigation on H. macrophylla anthracnose was carried out in nine parks of Beijing, China, and a total of 114 Colletotrichum isolates were obtained from the diseased leaves with typical anthracnose symptoms. Based on morphological characteristics and phylogenetic analysis of six genomic loci including rDNA-ITS, ACT, TUB2, CAL, CHS-1, and GAPDH, these isolates were identified as belonging to six Colletotrichum species. Among which, C. gloeosporioides was the most abundant (65 isolates, 57.0%), followed by C. fructicola (33 isolates, 28.9%), C. aenigma (8 isolates, 7.0%), C. truncatum (4 isolates, 3.5%), C. subacidae (2 isolates, 1.8%) and C. sojae (2 isolates, 1.8%). Pathogenicity test conducted on detached leaves of H. macrophylla revealed a distinct variation in virulence among isolates from different Colletotrichum species, and wounding was either essential or conducive to successful infection. Specifically, C. gloeosporioides exhibited greater aggressiveness, resulting in larger lesions, while C. subacidae induced lesions most quickly. Fungicide sensitivity assays demonstrated that prochloraz exerted a remarkable inhibitory effect on the mycelial growth of representative isolates belonging to the three predominant Colletotrichum species. In contrast to difenoconazole and tebuconazole, the mean EC50 values for prochloraz against C. gloeosporioides, C. fructicola, and C. aenigma were 0.062, 0.033, and 0.023 μg/ml, respectively. This is the first report of C. aenigma, C. truncatum, C. subacidae and C. sojae causing H. macrophylla anthracnose worldwide including China. These findings have elucidated the Colletotrichum species associated with H. macrophylla anthracnose as well as their fungicides sensitivities in Beijing, China. This provides a scientific foundation for the accurate diagnosis and local management of H. macrophylla anthracnose.

To investigate the effect of steel slag used as substrate on the rooting of Hydrangea macrophylla cuttings, and to develop a new mixed substrate that can partially replace conventional cutting substrates and realize the high-efficient utilization of solid waste, we examined the physical and chemical properties of different mixed substrates containing 10% (T,), 20% ( T2), 30% (T3), and 40% (T4) volume fractions of steel slag, and investigated the rooting of H. macrophylla ' Red Beauty' cuttings growing on these substrates, with conventional cutting substrates (peat and perlite) as the control (CK). The results showed that pH value, electrical conductivity, and bulk density of the mixed substrates were significantly higher than those of CK. The aeration porosity of T2 was higher than other treatments, while the total porosity and water holding porosity differed little from others. Both fresh weight and dry weight of all the four treatments were higher than those of CK, with stem diameter being higher than that of CK ( except T4), plant height showing no significant difference compared to CK ( except T4), and leaf chlorophyll content being significantly lower than CK. Root length ranked as T2 >CK>T, >T3 >T4, the root surface area and root volume both ranked as T2>T, >CK>T4>T3, the root tip ranked as T2>CK>T, >T4>T3. Both average root diameter and root activity were significantly higher than that of CK, with the highest value being observed in T2. Soluble sugar content in the leaves of T2 was the highest, followed by T4, T3, CK, and T,. The weight ranking of root growth indices was root activity > average root diameter > root volume > root surface area > root tip number > root length. Redundancy analysis indicated that pH value, electrical conductivity, aeration porosity, and water holding porosity of substrates were key factors influencing root growth and development of cuttings. Our results suggested that substrates mixed with 10% to 40% steel slag could be used for H. macrophylla cutting propagation, and 20% ( T2) being the best one because it could significantly improve the survival rate, growth status, and root development of cuttings. Steel slag would be a novel substrate to partially replace conventional unrenewable substrates such as peat and perlite for flower seedling propagation, which could reduce agricultural production cost and provide a high-value utilization way of industry solid waste. [ABSTRACT FROM AUTHOR]

We confirmed that the hexane layer of Hydrangea macrophylla leaf extract (HLH) is rich in phyllodulcin (PD), an alternative sweetener, through high performance liquid chromatography (HPLC) analysis. To investigate in vivo activity of HLH and its PD, acute toxicity and growth rate of Caenorhabditis elegans were tested and there are no clinical abnormalities at 125-500 µg/mL of HLH. HLH decreased the total lipid and triglyceride contents dose-dependently in glucose-induced obese worms. Also, HLH increased survival rates under oxidative and thermal stress and decreased body reactive oxygen species (ROS) contents significantly. Such antioxidant properties of HLH were attributed to the enhanced activity of the antioxidant enzyme catalase. To determine whether the effect of HLH was due to PD, worms were treated with PD (concentration contained in HLH), and inhibitory effects on total lipids and ROS were observed. Our results suggest that HLH and its PD as a natural alternative sweetener can be used as materials to improve metabolic diseases. [ABSTRACT FROM AUTHOR]

Hydrangea macrophylla is an ornamental plant with varied calyx colors. Interestingly, from red, to purple, to blue, the colors of all Hydrangea macrophylla are formed by unique delphinidin-3-O-glucoside and aluminum ions (Al3+) and 5-O-p-coumaroylquinic acid. The sepals of 'Blue Mama' changed from pink to blue, and the contents of delphinidin-3-O-glucoside and aluminum ions increased under 3 g/L aluminum sulfate treatment. However, the mechanism of the effect of aluminum ions on the synthesis and metabolism of anthocyanins in Hydrangea macrophylla is still unclear. In this project, transcriptome sequencing and anthocyanin metabolome analysis were performed on the sepals of 'Blue Mama' during flower development at the bud stage (S1), discoloration stage (S2) and full-bloom stage (S3) under aluminum treatment. It was found that delphinidin, delphinidin-3-O-glucoside and delphinidin-3-O-galactoside were the main differential metabolites. The structural genes CHS, F3H, ANS, DFR and BZI in the anthocyanin synthesis pathway were up-regulated with the deepening in sepal color. There was no significant difference between the aluminum treatment and the non-aluminum treatment groups. However, seven transcription factors were up-regulated and expressed to regulate anthocyanin synthesis genes CHS, F3H, BZI and 4CL, promoting the sepals to turn blue. The KEGG enrichment pathway analysis of differentially expressed genes showed that the glutathione metabolism and the ABC transporter pathway were closely related to anthocyanin synthesis and aluminum-ion transport. GST (Hma1.2p1_0158F.1_g069560.gene) may be involved in the vacuolar transport of anthocyanins. The expression of anthocyanin transporter genes ABCC1 (Hma1.2p1_0021F.1_g014400.gene), ABCC2 (Hma1.2p1_0491F.1_g164450.gene) and aluminum transporter gene ALS3 (Hma1.2p1_0111F.1_g053440.gene) were significantly up-regulated in the aluminum treatment group, which may be an important reason for promoting the transport of anthocyanin and aluminum ions to vacuoles and making the sepals blue. These results preliminarily clarified the mechanism of aluminum ion in the synthesis and transport of anthocyanin in Hydrangea macrophylla, laying a foundation for the further study of the formation mechanism of 'blue complex' in Hydrangea macrophylla. [ABSTRACT FROM AUTHOR]

Hydrangea macrophylla, a celebrated ornamental worldwide, thrives in semi-shaded growth environments in its natural habitat. This study utilizes Hydrangea macrophylla 'Endless Summer' as the experimental material to delve into its molecular mechanisms for adapting to semi-shaded conditions. Transcriptome analysis was conducted on leaves from four different natural light growth scenarios, showcasing phenotypic variations. From each sample, we obtained over 276,305,940 clean reads. Following de novo assembly and quantitative assessment, 88,575 unigenes were generated, with an average length of 976 bp. Gene ontology analysis of each control group elucidated the terms associated with the suitable environmental conditions for normal growth, development, and flowering, such as "reproductive bud system development" and "signal transduction". The exploration of gene interactions and the identification of key genes with strong connectivity were achieved by constructing a protein–protein interaction (PPI) network. The results indicate that hydrangea grows vigorously and blooms steadily under semi-shaded conditions; the photosynthetic efficiency of hydrangea is stabilized through genes related to photosynthesis, such as PHYB, PSBR, FDC, etc. Hormone signal transduction genes like PIN3, LAX2, TIF6B, and EIN3 play important roles in responding to environmental stimulation and regulating growth and development, while genes such as SOC1, COL4/5/16, and AGL24 promote flowering. The expression of genes such as BGLUs and TPSs provides additional energy substances to support flowering. [ABSTRACT FROM AUTHOR]

Hydrangea macrophylla is a garden plant widely cultivated in Asia, America, and Europe with its inflorescence as main ornamental feature. It is commonly used in interior decoration and landscape creation. To investigate the role of AP3 gene in hydrangea during calyx formation, H. macrophylla ‘Dooley’ was used as the material. The MADS-box Class B gene HmAP3 was cloned, and its gene function was predicted by bioinformatics analysis. To explore methods for quicker breeding new varieties, highly-specific editing targets were screened and CRISPR/Cas9 gene-editing vectors were constructed. The vector sequence was integrated into the H. macrophylla genome by agrobacterium-mediated transformation. The results were as follows: (1) The cDNA sequence full length of HmAP3 was 546 bp, encoding 181 amino acids. Its amino acid sequence was 100% similar to the reference sequence and 58.8% similar to Arabidopsis thaliana. (2) AP3 differed greatly in different genera. Within the same genus, the main structure of AP3 protein was conserved and differed only in a few motifs. (3) There were two highly specific targets in HmAP3. Sequencing results indicated that two single-target CRISPR/Cas9 gene-editing vectors were constructed successfully. (4) There were five resistant buds with Cas9 sequences in their genomes. However, their target sequences did not change due to the absence of Cas9 expression. In this study, the potential of AP3 gene in the breeding work of double flower phenotype was investigated, and a preliminary exploration of CRISPR/Cas9 gene-editing technology for Hydrangea macrophylla was conducted. These results provide a basis for the breeding of H. macrophylla.

Hydrangea macrophylla, renowned for its large inflorescences and a diverse range of colors, highlights a significant limitation in current gene function research, which is the lack of effective molecular genetic tools. This study utilized a tobacco rattle virus (TRV)-based virus-induced gene silencing (VIGS) system to investigate gene function through posttranscriptional gene silencing in H. macrophylla for the first time. The ortholog of phytoene desaturase (PDS) in H. macrophylla, termed HmPDS, was identified. Infection of tissue-cultured seedlings with TRV-HmPDS led to photobleaching of the leaves. Additionally, infection with TRV containing the HmCHS1 fragment in the flowers resulted in decreased anthocyanin production in sepals and a lightening of sepal coloration in the infected flowers. The phenomena and RT-qPCR results proved that the PDS and CHS genes of hydrangea were successfully silenced via the vacuum infiltration method. Furthermore, the introduction of TRV-HmF3′5′H revealed a decrease in delphinidin-3-glucoside content in sepals and caused a color change in the sepals from blue to pink. This study demonstrated that the TRV-VIGS system was successfully established in H. macrophylla and effectively applied to the function analysis of HmF3′5′H.

Hydrangea macrophylla (H. macrophylla), a species in the genus Hydrangea in the family Hydrangeaceae, is widely valued for its ornamental qualities in both domestic and international markets. Notably, H. macrophylla is known for its ability to accumulate aluminum (Al). Moreover, aluminum ions (Al3+) participate in sepal bluing. However, the underlying mechanisms of Al accumulation in the sepals remain unclear. In this study, we utilized transcriptome data from two cultivars to identify genes associated with Al accumulation. In total, 154 differentially expressed isoforms between the CK and Tr groups in the sepals of both cultivars were screened. Through gene enrichment analysis and similarity identification in the CDS (coding sequence) region, 43 differentially expressed genes were identified, including 30 upregulated and 13 downregulated genes, in the sepals of the Al treatment group. Further analysis revealed that seven of these upregulated genes are related to Al accumulation in sepals. Among the seven, the gene HmALS3.1 was identified as a potential key player in Al transport within the sepals of H. macrophylla. This study lays the groundwork for further exploration into the mechanisms by which HmALS3.1 regulates Al accumulation in H. macrophylla.

Steel slag is an industrial solid waste produced during the steelmaking process. To explore the application of steel slag in the agricultural field, the present experiment was carried out to study the effect of substrates with different contents of steel slag on the growth of Hydrangea macrophylla cuttings. The conventional substrate (perlite: vermiculite: peat = 1:1:1) was used as the control (CK), and the treatments were designed as T1 (steel slag: perlite: vermiculite: peat = 1:3:3:3, v/v/v/v), T2 (steel slag: perlite: vermiculite: peat = 1:2:2:2, v/v/v/v), T3 (steel slag: perlite: vermiculite: peat = 1:1:1:1, v/v/v/v), and T4 (steel slag: perlite: vermiculite: peat = 1:0:0:0, v/v/v/v). The results showed that the addition of steel slag significantly increased the substrate’s bulk density, EC, and pH and improved its water retention capacity to a certain extent. There were significant differences among different treatments in morphological indicators, root growth and development, and physiological and biochemical characteristics of cutting seedlings. All traits, including plant height, fresh weight, dry weight, root length, root surface area, root volume, the number of root tips, root activity, and soluble protein content of seedlings grown in T3 were significantly higher than those in other substrates. The results indicated that the appropriate addition of steel slag is helpful to hydrangea cuttings’ growth, and the optimal mixing ratio is steel slag: perlite: vermiculite: peat = 1:1:1:1 (v/v/v/v). This is a significant innovation in applying steel slag in agricultural production.

Hydrangea macrophylla, commonly known as bigleaf, garden, French, or florist hydrangea, is the most economically important member of the Hydrangea genus, with a breeding history spanning hundreds of years. Bigleaf hydrangea breeding improvement has largely focused on aesthetic traits and there are few varieties tolerant or resistant to major diseases such as powdery mildew. Powdery mildew is an obligate biotrophic Ascomycete in the order Erysiphales represented by approximately 900 species worldwide. The disease-causing agent in hydrangeas is Golovinomyces orontii (formerly Erysiphe polygoni DC), which tarnishes the beauty, growth, and salability of bigleaf hydrangea plants, especially those packed closely in production environments. Chemical or biological control is commonly used in production. A recently published haplotype-resolved genome of bigleaf hydrangea enables targeted analyses and breeding techniques for powdery mildew resistance. Analyzing transcriptomes of tolerant and susceptible hydrangeas through RNA sequencing will lead to the identification of differentially expressed genes and/or pathways. Concurrent application of marker-assisted selection, genetic transformation, and gene editing will contribute to the development of powdery-mildew-resistant varieties of bigleaf hydrangea. The aim of this review is to give a general overview of powdery mildew, its impact on bigleaf hydrangea, current control methods, molecular mechanisms, and breeding prospects for powdery mildew resistance in bigleaf hydrangea. [ABSTRACT FROM AUTHOR]

Background: WD40 transcription factors are crucial in plant growth and developmental, significantly impacting plant growth regulation. This study investigates the WD40 transcription factor HmWDR68's role in developing the distinctive blue infertile flower colors in Hydrangea macrophylla 'Forever Summer'. Methods and results: The HmWDR68 gene was isolated by PCR, revealing an open reading frame of 1026 base pairs, which encodes 341 amino acids. Characterized by four WD40 motifs, HmWDR68 is a member of the WD40 family. Phylogenetic analysis indicates that HmWDR68 shares high homology with PsWD40 in Camellia sinensis and CsWD40 in Paeonia suffruticosa, both of which are integral in anthocyanin synthesis regulation. Quantitative real-time PCR (qRT-PCR) analysis demonstrated that HmWDR68 expression in the blue infertile flowers of 'Forever Summer' hydrangea was significantly higher compared to other tissues and organs. Additionally, in various hydrangea varieties with differently colored infertile flowers, HmWDR68 expression was markedly elevated in comparison to other hydrangea varieties, correlating with the development of blue infertile flowers. Pearson correlation analysis revealed a significant association between HmWDR68 expression and the concentration of delphinidin 3-O-glucoside, as well as key genes involved in anthocyanin biosynthesis (HmF3H, HmC3'5'H, HmDFR, and HmANS) in the blue infertile flowers of 'Forever Summer' hydrangea (P < 0.01). Conclusion: These findings suggest HmWDR68 may specifically regulate blue infertile flower formation in hydrangea by enhancing delphinidin-3-O-glucoside synthesis, modulating expression of HmF3H, HmC3'5'H, HmDFR and HmANS. This study provides insights into HmWDR68's role in hydrangea's blue flowers development, offering a foundation for further research in this field. [ABSTRACT FROM AUTHOR]

The efficacy of the fungicide pydiflumetofen + difenoconazole (Postiva) was evaluated at varying application rates and intervals for the control of powdery mildew (Golovinomyces orontii, formerly Erysiphe polygoni) in bigleaf hydrangea (Hydrangea macrophylla 'Nikko Blue'). Container-grown hydrangeas were arranged in a completely randomized design with six single-plant replications. Experiments were done in 2022 and 2023 under both greenhouse and shade house conditions (56% shade). Powdery mildew in hydrangea was developed naturally. Pydiflumetofen + difenoconazole at 1.1, 1.6, and 2.2 ml·L21 and a standard fungicide azoxystrobin + benzovindiflupyr (Mural) at 0.5 g·L21 were sprayed to runoff on 2-, 4-, and 6-week intervals. Plants that were not treated with fungicide served as the control. Plants were evaluated weekly for disease severity (0% to 100% foliage affected) and defoliation (0% to 100% defoliation). The season-long area under the disease progress curve (AUDPC) and defoliation progress curve (AUDFC) were calculated for the evaluation period. The initial and final plant height and width were recorded, and height and width increase were determined. Pydiflumetofen + difenoconazole and azoxystrobin + benzovindiflupyr significantly reduced final disease severity, AUDPC, and defoliation both in the greenhouse and shade house compared with control plants. In both greenhouse trials and the 2022 shade house trial, AUDFC was reduced in all treatments compared with the control plants. However, AUDFC was not reduced by all treatments in the 2023 shade house trial. Pooled over application intervals, the low rate of pydiflumetofen + difenoconazole was as effective as the medium and high rates of pydiflumetofen + difenoconazole and azoxystrobin + benzovindiflupyr in reducing final powdery mildew severity and AUDPC both in the greenhouse and shade house in both 2022 and 2023. No significant differences between application intervals were noted in final disease severity and progress. Control of powdery mildew with fungicides failed to increase plant dimensions (i.e., plant height and width) compared with the no fungicide control. Because all application rates and intervals of pydiflumetofen + difenoconazole provided comparable powdery mildew disease control, it is suggested that using a low rate of pydiflumetofen + difenoconazole with the longest application interval (6 weeks) is the most cost-effective approach for managing powdery mildew in bigleaf hydrangeas. [ABSTRACT FROM AUTHOR]

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Hydrangea macrophylla is an ornamental plant with varied calyx colors. Interestingly, from red, to purple, to blue, the colors of all Hydrangea macrophylla are formed by unique delphinidin-3-O-glucoside and aluminum ions (Al3+) and 5-O-p-coumaroylquinic acid. The sepals of ‘Blue Mama’ changed from pink to blue, and the contents of delphinidin-3-O-glucoside and aluminum ions increased under 3 g/L aluminum sulfate treatment. However, the mechanism of the effect of aluminum ions on the synthesis and metabolism of anthocyanins in Hydrangea macrophylla is still unclear. In this project, transcriptome sequencing and anthocyanin metabolome analysis were performed on the sepals of ‘Blue Mama’ during flower development at the bud stage (S1), discoloration stage (S2) and full-bloom stage (S3) under aluminum treatment. It was found that delphinidin, delphinidin-3-O-glucoside and delphinidin-3-O-galactoside were the main differential metabolites. The structural genes CHS, F3H, ANS, DFR and BZI in the anthocyanin synthesis pathway were up-regulated with the deepening in sepal color. There was no significant difference between the aluminum treatment and the non-aluminum treatment groups. However, seven transcription factors were up-regulated and expressed to regulate anthocyanin synthesis genes CHS, F3H, BZI and 4CL, promoting the sepals to turn blue. The KEGG enrichment pathway analysis of differentially expressed genes showed that the glutathione metabolism and the ABC transporter pathway were closely related to anthocyanin synthesis and aluminum-ion transport. GST (Hma1.2p1_0158F.1_g069560.gene) may be involved in the vacuolar transport of anthocyanins. The expression of anthocyanin transporter genes ABCC1 (Hma1.2p1_0021F.1_g014400.gene), ABCC2 (Hma1.2p1_0491F.1_g164450.gene) and aluminum transporter gene ALS3 (Hma1.2p1_0111F.1_g053440.gene) were significantly up-regulated in the aluminum treatment group, which may be an important reason for promoting the transport of anthocyanin and aluminum ions to vacuoles and making the sepals blue. These results preliminarily clarified the mechanism of aluminum ion in the synthesis and transport of anthocyanin in Hydrangea macrophylla, laying a foundation for the further study of the formation mechanism of ‘blue complex’ in Hydrangea macrophylla.

To explain the reason for different flower color adjustabilities of Hydrangea macrophylla, non-adjustable color ‘Tijana’ and adjustable color ‘Ravi Brent’ of Hydrangea macrophylla were used as experimental materials. The extraction conditions were optimized and the components of H. macrophylla anthocyanins were measured. Their physical-chemical stabilities were also explored, aiming to explore the mechanism of flower color adjustability. The optimal extraction conditions of Hydrangea anthocyanins by the ultrasonic method were determined through L9（33）orthogonal experiments. The anthocyanin components were separated and identified by UPLC-Q-TOF-MS. And the effects of temperature, light, metal ions and sugars on the physical-chemical stabilities of H. macrophylla anthocyanins were also explored in vitro conditions. The results were as follows: (1) The optimal conditions for extraction of H. macrophylla anthocyanins were that the ethanol concentration for ‘Tijana’ and ‘Ravi Brent’ were 70% and 80% respectively; the ratio of plant material to extraction solution was both 1∶20; and the extraction time was both 20 m. (2) The main anthocyanin component of the two varieties was both Delphinidin 3-O-glucoside. (3) H. macrophylla anthocyanins were more stable when stored below 70℃ and in the dark. (4) Both Cu2+ and Al3+ change the color of the anthocyanin solution, and Cu2+ specifically improved the stability of the anthocyanin of ‘Tijana’. 10-90 mmol·L-1 Ca2+, Al3+ and 90 mmol·L-1 Mg2+ had significant effects on the stability of anthocyanin of both varieties. Glucose, maltose, sucrose, galactose and 8%-10% concentration of rhamnose increased the stability of the non-adjustable color ‘Tijana’ Hydrangea macrophlla anthocyanins. While 4%-10% concentration of rhamnose promoted the stability of adjustable color ‘Ravi Brent’ Hydrangea macrophylla anthocyanins. The non-adjustable color ‘Tijana’ of H. macrophylla anthocyanins were more stable to light, sugars and most metal ions, compared with the adjustable color ‘Ravi Brent’. Only the anthocyanins of the adjustable color ‘Ravi Brent’ of H. macrophylla turned from pink to blue, and its stability increased after adding low medium concentration (10-30 mmol·L-1) of Al3+. However, the non-adjustable color ‘Tijana’ of H. macrophylla did not have this kind of color change, indicating that the difference in color adjustability of H. flowers is related to its physical-chemical stability. These results provide the theoretical reference for the extraction and observation of H. macrophlla anthocyanins, flower color improvement and dry flower color protection.

Hydrangea macrophylla is popular for its unique physiological characteristics and changeable colors. Previous studies have shown that the pH of the vacuoles of the sepal cells of hydrangea affects the color of the sepals. Located on the vacuolar membrane, NHX1 is an important H+ proton pump that drives the exchange of metal ions. This proton pump affects the physiological environment by controlling the accumulation of H+ in the vacuole. In hydrangea, the HmNHX1 gene has an open reading frame of 1626 bp and encodes a total of 541 amino acids. Bioinformatic analysis showed that HmNHX1, which encodes a Na+/H+ exchanger, is located on the vacuolar membrane. Tissue-specific expression analysis showed that the expression of this gene in the treatment group was higher than that in the control group. The ion flux in the vacuoles of colored hydrangea in the treatment group and the control group were measured, and the results showed that HmNHX1 was indeed a Na+/H+ exchanger. When the results of the HmNHX1 expression analysis and ion flux measurements are combined, it can be seen that HmNHX1 regulates the accumulation of H+ in the vacuole, ultimately affecting the color of the plant.

Hydrangea macrophylla is an important ornamental plant with a high market value and is widely planted in Guizhou, China. Leaf spot disease in H. macrophylla is common in Shibing County, Guizhou Province, where the estimated disease incidence is 70%–80%, seriously affecting its ornamental value. In this study, we isolated the pathogen from diseased samples of H. macrophylla in Shibing, Guizhou, verified the pathogenicity by Koch's postulates and identified the pathogen by combining the morphological characters with molecular systematics based on DNA sequences of the internal transcribed spacer regions (ITS), partial regions of RNA polymerase II second largest subunit (RPB2), β‐tubulin (TUB), and partial 28S large subunit of the nrRNA gene (LSU). The pathogen causing leaf spot disease was identified as Epicoccum sorghinum. The inhibitory effects of six synthetic fungicides on the pathogen were measured using the poison food technique. In this analysis, 25% pyraclostrobin SC exhibited the strongest inhibitory effect, with an EC50 (concentration producing 50% of the maximal effect) of 0.0208 mg/L, followed by 10% difenoconazole WDG, with an EC50 of 0.0995 mg/L. The results of this study provide a theoretical reference for the prevention and control of leaf spot disease. [ABSTRACT FROM AUTHOR]

Hydrangea macrophylla, a celebrated ornamental worldwide, thrives in semi-shaded growth environments in its natural habitat. This study utilizes Hydrangea macrophylla ‘Endless Summer’ as the experimental material to delve into its molecular mechanisms for adapting to semi-shaded conditions. Transcriptome analysis was conducted on leaves from four different natural light growth scenarios, showcasing phenotypic variations. From each sample, we obtained over 276,305,940 clean reads. Following de novo assembly and quantitative assessment, 88,575 unigenes were generated, with an average length of 976 bp. Gene ontology analysis of each control group elucidated the terms associated with the suitable environmental conditions for normal growth, development, and flowering, such as “reproductive bud system development” and “signal transduction”. The exploration of gene interactions and the identification of key genes with strong connectivity were achieved by constructing a protein–protein interaction (PPI) network. The results indicate that hydrangea grows vigorously and blooms steadily under semi-shaded conditions; the photosynthetic efficiency of hydrangea is stabilized through genes related to photosynthesis, such as PHYB, PSBR, FDC, etc. Hormone signal transduction genes like PIN3, LAX2, TIF6B, and EIN3 play important roles in responding to environmental stimulation and regulating growth and development, while genes such as SOC1, COL4/5/16, and AGL24 promote flowering. The expression of genes such as BGLUs and TPSs provides additional energy substances to support flowering.

Horticultural production systems have to move forwards to an environment-friendly and sustainable plant production. Basic substances can be added to reduce the use of synthetic plant protectant in conventional plant protection strategies. Regarding the protection of ornamental plants, less is known about the usage and behaviour of these alternative strategies and components. In our study, an infection of Podosphaera pannosa and Erysiphe polygoni in two different cultivars of cutting roses and one cultivar of French hydrangea was investigated. We studied the effect of a weekly foliar treatment of the basic substance chitosan (0.05 g/m2) compared to a water control and potassium hydrogen carbonate (VitiSan, Biofa GmbH, Münsing, Germany) in both production systems. As a result, in cutting roses as well as in French hydrangea, we found a significantly decreased infected leaf area following the use of chitosan and VitiSan compared to the water control. In both treatments, we found a stronger effect in French hydrangea, compared to roses. Results also indicate that the basic substance chitosan has to be used at a low pathogen level. We present a promising approach to reduce conventional plant protectants in ornamental plant production. [ABSTRACT FROM AUTHOR]

The flower induction of Hydrangea macrophylla "Endless Summer" is regulated by a complex gene network that involves multiple signaling pathways to ensure continuous flowering throughout the growing season, but the molecular determinants of flower induction are not yet clear. In this study, genes potentially involved in signaling pathway mediating the regulatory mechanism of flower induction were identified through the transcriptomic profiles, and a hypothetical model for this regulatory mechanism was obtained by an analysis of the available transcriptomic data, suggesting that sugar-, hormone-, and flowering-related genes participated in the flower induction process of H. macrophylla "Endless Summer". The expression profiles of the genes involved in the biosynthesis and metabolism of sugar showed that the beta-amylase gene BAM1 displayed a high expression level at the BS2 stage and implied the hydrolysis of starch. It may be a signaling molecule that promotes the transition from vegetative growth to reproductive growth in H. macrophylla "Endless Summer". Complex hormone regulatory networks involved in abscisic acid (ABA), auxin (IAA), zeatin nucleoside (ZR), and gibberellin (GA) also induced flower formation in H. macrophylla. ABA participated in flower induction by regulating flowering genes. The high content of IAA and the high expression level of the auxin influx carrier gene LAX5 at the BS2 stage suggested that the flow of auxin between sources and sinks in H. macrophylla is involved in the regulation of floral induction as a signal. In addition, flowering-related genes were mainly involved in the photoperiodic pathway, the aging pathway, and the gibberellin pathway. As a result, multiple pathways, including the photoperiodic pathway, the aging pathway, and the gibberellin pathway, which were mainly mediated by crosstalk between sugar and hormone signals, regulated the molecular network involved in flower induction in H. macrophylla "Endless Summer". [ABSTRACT FROM AUTHOR]

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Abstract Background Hydrangea macrophylla var. Maculata ‘Yinbianxiuqiu’ (YB) is an excellent plant species with beautiful flowers and leaves with silvery white edges. However, there are few reports on its leaf color characteristics and color formation mechanism. Results The present study compared the phenotypic, physiological and transcriptomic differences between YB and a full-green leaf mutant (YM) obtained from YB. The results showed that YB and YM had similar genetic backgrounds, but photosynthesis was reduced in YB. The contents of pigments were significantly decreased at the edges of YB leaves compared to YM leaves. The ultrastructure of chloroplasts in the YB leaves was irregular. Transcriptome profiling identified 7,023 differentially expressed genes between YB and YM. The expression levels of genes involved in photosynthesis, chloroplast development and division were different between YB and YM. Quantitative real-time PCR showed that the expression trends were generally consistent with the transcriptome data. Conclusions Taken together, the formation of the silvery white leaf color of H. macrophylla var. maculata was primarily due to the abnormal development of chloroplasts. This study facilitates the molecular function analysis of key genes involved in chloroplast development and provides new insights into the molecular mechanisms involved in leaf coloration in H. macrophylla.

Hydrangea macrophylla, commonly known as bigleaf, garden, French, or florist hydrangea, is the most economically important member of the Hydrangea genus, with a breeding history spanning hundreds of years. Bigleaf hydrangea breeding improvement has largely focused on aesthetic traits and there are few varieties tolerant or resistant to major diseases such as powdery mildew. Powdery mildew is an obligate biotrophic Ascomycete in the order Erysiphales represented by approximately 900 species worldwide. The disease-causing agent in hydrangeas is Golovinomyces orontii (formerly Erysiphe polygoni DC), which tarnishes the beauty, growth, and salability of bigleaf hydrangea plants, especially those packed closely in production environments. Chemical or biological control is commonly used in production. A recently published haplotype-resolved genome of bigleaf hydrangea enables targeted analyses and breeding techniques for powdery mildew resistance. Analyzing transcriptomes of tolerant and susceptible hydrangeas through RNA sequencing will lead to the identification of differentially expressed genes and/or pathways. Concurrent application of marker-assisted selection, genetic transformation, and gene editing will contribute to the development of powdery-mildew-resistant varieties of bigleaf hydrangea. The aim of this review is to give a general overview of powdery mildew, its impact on bigleaf hydrangea, current control methods, molecular mechanisms, and breeding prospects for powdery mildew resistance in bigleaf hydrangea.

The lactic acid bacteria, Lactococcus lactis subsp. lactis LM1185 was isolated from Hydrangea macrophylla. Strain LM1185 showed 50.5% of acid tolerance at pH 2.5 for 2 h and 30.4% of 0.3% (w/v) bile salt tolerance for 24 h. The antioxidant activity of this strain was measured at 99.4% of 2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging activity. When RAW 264.7 macrophage cells were treated with strain LM1185, there was no observed cytotoxicity. This strain showed high nitric oxide production and mRNA expression levels of cytokines such as tumor necrosis factor-α and inducible nitric oxide synthase (iNOS). The nuclear factor-kB signaling pathway was activated by this strain resulting in the production of iNOS and cyclooxygenase-2 determined by western blotting. The present results indicated that L. lactis subsp. lactis LM1185 could be used as potential probiotics and may play a crucial role in the immunostimulatory effect on macrophages. [ABSTRACT FROM AUTHOR]

Hydrangea macrophylla is popular for its unique physiological characteristics and changeable colors. Previous studies have shown that the pH of the vacuoles of the sepal cells of hydrangea affects the color of the sepals. Located on the vacuolar membrane, NHX1 is an important H+ proton pump that drives the exchange of metal ions. This proton pump affects the physiological environment by controlling the accumulation of H+ in the vacuole. In hydrangea, the HmNHX1 gene has an open reading frame of 1626 bp and encodes a total of 541 amino acids. Bioinformatic analysis showed that HmNHX1, which encodes a Na+/H+ exchanger, is located on the vacuolar membrane. Tissue-specific expression analysis showed that the expression of this gene in the treatment group was higher than that in the control group. The ion flux in the vacuoles of colored hydrangea in the treatment group and the control group were measured, and the results showed that HmNHX1 was indeed a Na+/H+ exchanger. When the results of the HmNHX1 expression analysis and ion flux measurements are combined, it can be seen that HmNHX1 regulates the accumulation of H+ in the vacuole, ultimately affecting the color of the plant. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the effect of different sugar types on the vase life of cut hydrangea flowers. There were 19 treatments based on concentrations and combinations of sucrose, glucose, and mannitol. The results showed that the vase solution with 5% glucose provided the most extended vase life, which was 12.4 d, while the control solution with distilled water recorded 8.86 d. The results were correlated with the total solution uptake, the number of days for reaching maximum inflorescent diameter, maximum sepal hardness score, chlorophyll content, and sepal electrolyte leakage. It could be implied that glucose alone extends hydrangea vase life by inactivating the ethylene signalling pathway. Based on the sepal size and colour, 3% glucose treatment, which generated the secondhighest vase life, could be the appropriate concentration for improving flower quality and longevity. This study provides the essential information that will lead to understanding hydrangea flower senescence and developing better vase solutions for cut hydrangea flowers. [ABSTRACT FROM AUTHOR]

With its large inflorescences and colorful flowers, Hydrangea macrophylla has been one of the most popular ornamental plants in recent years. However, the formation mechanism of its major ornamental part, the decorative floret sepals, is still not clear. In this study, we compared the transcriptome data of H. macrophylla 'Endless Summer' from the nutritional stage (BS1) to the blooming stage (BS5) and annotated them into the Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) databases. The 347 identified differentially expressed genes (DEGs) associated with flower development were subjected to a trend analysis and a protein–protein interaction analysis. The combined analysis of the two yielded 60 DEGs, including four MADS-box transcription factors (HmSVP-1, HmSOC1, HmAP1-2, and HmAGL24-3) and genes with strong connectivity (HmLFY and HmUFO). In addition, 17 transcription factors related to the ABCDE model were screened, and key candidate genes related to the development of decorative floret sepals in H. macrophylla were identified by phylogenetic and expression pattern analysis, including HmAP1-1, HmAP1-2, HmAP1-3, HmAP2-3, HmAP2-4, and HmAP2-5. On this basis, a gene regulatory network model of decorative sepal development was also postulated. Our results provide a theoretical basis for the study of the formation mechanism of decorative floret sepals and suggest a new direction for the molecular breeding of H. macrophylla. [ABSTRACT FROM AUTHOR]

Abstract Climate change has a significant impact on the growth and distribution of vegetation worldwide. Hydrangea macrophylla is widely distributed and considered a model species for studying the distribution and responses of shrub plants under climate change. These results can inform decision‐making regarding shrub plant protection, management, and introduction of germplasm resources, and are of great importance for formulating ecological countermeasures to climate change in the future. We used the maximum entropy model to predict the change, scope expansion/reduction, centroid movement, and dominant climate factors that restrict the growth and distribution of H. macrophylla in China under current and future climate change scenarios. It was found that both precipitation and temperature affect the distribution of suitable habitat for H. macrophylla. Akaike information criterion (AICc) was used to select the feature combination (FC) and the regularization multiplier (RM). After the establishment of the optimal model (FC = QP, RM = 0.5), the complexity and over‐fitting degree of the model were low (delta AICc = 0, omission rate = 0.026, difference between training and testing area under the curve values = 0.0009), indicating that it had high accuracy in predicting the potential geographical distribution of H. macrophylla (area under the curve = 0.979). Overall, from the current period to future, the potential suitable habitat of this species in China expanded to the north. The greenhouse effect caused by an increase in CO2 emissions would not only increase the area of high‐suitability habitat in Central China, but also expand the area of total suitable habitat in the north. Under the maximum greenhouse gas emission scenario (RCP8.5), the migration distance of the centroid was the longest (e.g., By 2070s, the centroids of total and highly suitable areas have shifted 186.15 km and 89.84 km, respectively).

Aluminum toxicity poses a significant threat to plant growth, especially in acidic soils. Heavy metal ATPases (HMAs) are crucial for transporting heavy metal ions across plant cell membranes, yet their role in Al3+ transport remains unexplored. This study identified eight HmHMA genes in the genome of Hydrangea macrophylla, categorizing them into two major clades based on phylogenetic relationships. These genes were found unevenly distributed across six chromosomes. Detailed analysis of their physicochemical properties, collinearity, and gene structure was conducted. RNA-seq and qRT-PCR analyses revealed that specific HmHMA genes, notably HmHMA2, were predominantly expressed in roots and flowers under Al3+ stress, indicating their potential role in Al3+ tolerance. HmHMA2 showed significant expression in roots, especially under Al3+ stress conditions, and when expressed in yeast cells, it conferred resistance to aluminum and zinc but increased sensitivity to cadmium. Overexpression of HmHMA2 in hydrangea leaf discs significantly improved Al3+ tolerance, reduced oxidative stress markers like hydrogen peroxide and malondialdehyde, and enhanced antioxidant enzyme activity such as SOD, POD and CAT compared to controls. These findings shed lights on the potential role of HmHMAs in Al transport and tolerance in H. macrophylla. [Display omitted] • Al3+ toxicity significantly threatens plant growth, particularly in acidic soils. • Eight HmHMA genes in hydrangea were identified and categorized into two clades. • HmHMA2 mainly expressed in roots and flowers under Al3+ stress. • HmHMA2- OE improved Al3+ tolerance and reduced oxidative stress markers. [ABSTRACT FROM AUTHOR]

The compounds hydrangenol and hydrangenol 8-O-glucoside are abundant in Hydrangea macrophylla. This study investigated the effects of hydrangenol and hydrangenol 8-O-glucoside derived from H. macrophylla on atopic dermatitis (AD). Compared with hydrangenol 8-O-glucoside, hydrangenol resulted in more potent inhibition of interleukin 4 (IL-4) gene expression and β-hexosaminidase release, as well as more potent inhibition of the phosphorylation of signal transducer and activator of transcription 6 (STAT6). Ultra High-Performance Liquid Chromatography (UHPLC), the concentrations of hydrangenol were found to be lower than the concentration of hydrangenol 8-O-glucoside in H. macrophylla extracts. To increase the hydrangenol content of H. macrophylla extract, component conversion methods were studied. Conclusion, microwave processing was found to be the optimal method for deglycosylation. [ABSTRACT FROM AUTHOR]

Hydrangea [ Hydrangea macrophylla (Thunb.) Ser.] is a high aluminum-tolerant ornamental plant species, which has a specific characteristic of color change, ie. some cultivars' floral color will change from red to blue or blue-violet planted in acidic soil containing aluminum. This study aims to understand the complex molecular mechanisms of floral color change under Al stress, through comparative biochemistry and transcriptome analyses between an Al3+-sensitive cultivar 'Bailer' and insensitive cultivar 'Ruby' under Al-stress. The results of biochemistry analysis showed that 'Bailer' displayed higher contents of Al3+ and delphinium-3-O-glucoside than that of 'Ruby' after Al 2 (SO 4) 3 treating. Meanwhile, the transcriptome analysis of different tissues identified 12,321 differentially expressed genes (DEGs) in 'Bailer' and 6,703 in 'Ruby'. Transcriptome analysis showed that changes in genes' expression pattern in several genes and pathways [such as including metal transporters, reactive oxygen species (ROS) scavenging enzyme, plant hormone signal transduction and favonoid biosynthesis pathway] were the key contributors to the Al3+-sensitive cultivar 'Bailer'. Besides, gene co-expression network analysis (WGCNA) demonstrated that five hub genes, including ABC transporters (TRINITY_DN1053_c0_g1, TRINITY_DN3377_c0_g2), cationic amino acid transporter (TRINITY_DN9684_c0_g2), oligopeptide transporter (TRINITY_DN1147_c0_g2) and flavonol synthase (TRINITY_DN15902_c0_g1), played vital roles in the networks regulating Al tolerance in hydrangea. Furthermore, HmABCI17 ′s (TRINITY_DN1053_c0_g1) expression enhanced Al tolerance in yeast. The conclusions of this study are helpful to elucidate the differences and molecular mechanisms of different hydrangea cultivars on Al tolerance, and provide new insights into molecular assisted-screening for breeding blue flowers in hydrangea and other ornamental plants. [Display omitted] • Higher contents of Al3+ and delphinium-3-O-glucoside were showed in the Al-sensitive cultivar after Al 2 (SO 4) 3 treating. • Metal transporters, ROS scavenging enzyme, plant hormone signal transduction and favonoid biosynthesis pathway may be involved in the blue flower formation of hydrangea. • Five hub genes, including ABC transporters, play vital roles in the network regulating the Al tolerance in hydrangea. • HmABCI17′s expression enhances Al tolerance in yeast. [ABSTRACT FROM AUTHOR]

Background: Hydrangea macrophylla var. Maculata 'Yinbianxiuqiu' (YB) is an excellent plant species with beautiful flowers and leaves with silvery white edges. However, there are few reports on its leaf color characteristics and color formation mechanism. Results: The present study compared the phenotypic, physiological and transcriptomic differences between YB and a full-green leaf mutant (YM) obtained from YB. The results showed that YB and YM had similar genetic backgrounds, but photosynthesis was reduced in YB. The contents of pigments were significantly decreased at the edges of YB leaves compared to YM leaves. The ultrastructure of chloroplasts in the YB leaves was irregular. Transcriptome profiling identified 7,023 differentially expressed genes between YB and YM. The expression levels of genes involved in photosynthesis, chloroplast development and division were different between YB and YM. Quantitative real-time PCR showed that the expression trends were generally consistent with the transcriptome data. Conclusions: Taken together, the formation of the silvery white leaf color of H. macrophylla var. maculata was primarily due to the abnormal development of chloroplasts. This study facilitates the molecular function analysis of key genes involved in chloroplast development and provides new insights into the molecular mechanisms involved in leaf coloration in H. macrophylla. [ABSTRACT FROM AUTHOR]

In this study, a new virus was identified in French hydrangea plants, exhibiting chlorotic vein banding and necrotic ring spots on older leaves. The virus was mechanically transmitted to herbaceous hosts, in which it induced local and systemic or only local symptoms. The genome of the new virus was characterized and consisted of three RNA sequences that were 3422 (RNA 1), 2905 (RNA 2) and 2299 (RNA 3) nucleotides long, with five predicted open reading frames; RNA2 was bicistronic and contained conserved domains and motifs typical of ilarviruses. The phylogenetic analysis of the predicted proteins—p1, p2a, p3a and p3b—revealed its close relationship to recognized members of subgroup 2 within the genus Ilarvirus. Homologous antiserum was effective in the detection of the virus in plant extracts and no cross reactions with two other distinct members of subgroup 2 were observed. Overall, the biological features, phylogenetic relationships and serological data suggest that this virus is a new member of the genus, for which we propose the name hydrangea vein banding virus (HdVBV). [ABSTRACT FROM AUTHOR]

Some sweet tasting plant secondary metabolites are non-caloric or low nutritive compounds that have traditional use in food formulations. This mini-review focuses on conventional and advanced cultivation regimes of plants that accumulate sweet tasting or sweet taste modulating secondary metabolites of potential economic importance, in particular mogrosides (Siraitia grosvenorii), phyllodulcin (Hydrangea macrophylla), glycyrrhizin (Glycyrrhiza glabra), steviol glycosides (Stevia grosvenorii), and rubusoside (Rubus suavissimus). Consequential obstacles during the cultivation of Hydrangea macrophylla cultivars outside their natural habitat in a protected cultivation environment are addressed. Culturing at non-habitat locations facilitates short transportation routes of plant material for processing, which can be a key to an economically and environmentally compatible usage. The biosynthetic pathways, as far as known, are shortly mentioned. The proved or hypothetical degradation pathways of the compounds to minimalize environmental contamination are another focal point. [ABSTRACT FROM AUTHOR]

Botrytis cinerea is one of the problematic and notorious postharvest pathogens of bigleaf hydrangea (Hydrangea macrophylla) cut flowers. It causes flower blight, leaf blight, and stem rot, reducing the ornamental value (such as longevity, color, and texture) of flowers, ultimately making them unsalable. The objective of this study was to identify effective conventional fungicides and biorational products for botrytis blight management on bigleaf hydrangea cut flowers that can be easily and readily adopted by growers of ornamentals. Preventive preharvest whole-plant spray and postharvest dip treatment applications were used in this study. For the whole-plant spray applications, bigleaf hydrangea plants were sprayed with treatment solution 3 days before harvesting flowers. For the dip applications, cut flowers were dipped in treatment solutions after harvest. For both application types, flowers were inoculated with B. cinerea spores once treatment solutions dried. Flowers were stored in cold storage for 3 days and then displayed in conditions similar to retail stores. Botrytis blight disease severity, marketability of flower (postharvest vase life), phytotoxicity, and application residue were assessed in the study. Treatments showed variable efficacy in managing postharvest B. cinerea infection in bigleaf hydrangea cut flowers. Preventive preharvest whole-plant spray and postharvest dip applications of isofetamid and fluxapyroxad + pyraclostrobin significantly reduced the postharvest botrytis blight disease severity and area under disease progress curve (AUDPC) compared with the positive control (nontreated, inoculated with B. cinerea). When applied as a postharvest dip, the fungicide fludioxonil and biofungicide Aureobasidium pullulans strains DSM 14940 and DSM 14941 effectively lowered the disease severity and disease progress (AUDPC). These effective treatments also maintained a significantly longer postharvest vase life of bigleaf hydrangea cut flowers compared with the nontreated, inoculated control. The longer vase life may be attributed to lowered botrytis blight disease severity and the resultant proper physiological functioning of flowers.

Hydragea (Hydrangea macrophylla) is a garden plant commonly used in parks and landscapes globally. In late May 2023, brown necrotic spots surrounded by chlorotic halos were observed on the leaves of H. macrophylla (cv. Renate Steiniger) at the Suncheonman National Garden in Suncheon (34°55'45.6" N 127°30'26.5" E), South Korea. The affected area covered approximately 20 m2, with the disease incidence ranging from 2% to 5%. Concentric rings with light brown centers measuring 0.5 to 6 cm were observed on the upper sides of the leaves. To isolate the pathogens, each infected leaf from three different plants was cut into 5 × 5 mm pieces, surface-sterilized with 70% ethanol for 1 min, and rinsed three times with sterile distilled water. The samples were cultured on 1.5% water agar amended with 100 μg/mL of streptomycin in the dark at 25 °C. Single-spore isolation from the grown hyphae was performed on the obtained isolates (SYP-1229 to 1231). The fungal colony on potato dextrose agar was olivaceous gray with floccose aerial mycelia, and black pycnidia developed on the medium after 14 days. The conidia observed were hyaline, cylindrical to ellipsoidal-oblong, and aseptate, measuring 4.9 to 9.1 μm × 1.9 to 4.2 μm (avg. 6.3 × 2.7 μm, n = 100) (length × width). The isolates were identified as Boeremia sp. based on their morphological characteristics (Boerema, 1976; Boerema, 2004). For molecular identification, the internal transcribed spacer (GenBank accession nos.: OR682193-OR682195), actin (OR689851- OR689853), β-tubulin (OR689854- OR689856) and translation elongation factor-1 alpha (OR689857- OR689859) sequences from the isolates SYP-1229 to 1231 exhibited 100% (558/558 bp), 100% (263/263), 100% (314/314), and 100% (316/316) similarity, respectively, with Boeremia exigua (EU167567, EU880846, OP611549, and KY484684, respectively) in GenBank BLAST search. Phylogenetics based on concatenated ITS, ACT, TUB2, and TEF sequences, using the maximum likelihood method of MEGA X (Kumar et al., 2018), showed that sequences of SYP-1229 to 1231 were clustered in the same clade as B. exigua. For pathogenicity tests conducted in pots, 10 mL conidial suspension (1 × 106 conidia/mL) derived from isolate SYP-1229, which had been cultured on PDA for 14 days, was sprayed onto two leaves of each of three independent healthy 1-year-old hydrangeas (cv. Renate Steiniger). The leaves of the control plants were inoculated with sterile distilled water, which was also applied to two leaves of each of the three independent healthy plants. The inoculated plants were placed in clear plastic boxes to maintain high humidity and incubated at 25 °C under 18 h of light. Brown spot lesions were observed on the inoculated two leaves seven days after inoculation, whereas the control were asymptomatic. Similar pathogenicity results were obtained for all three independent biological replicates. The fungus isolated from the lesion was identified as B. exigua through morphological characterization and ITS sequencing, thus fulfilling Koch's postulates. To the best of our knowledge, this is the first report of B. exigua causing brown-spot disease on H. macrophylla in South Korea. The pathogen has been previously reported H. macrophylla in Italy and the United States (Farr and Rossman 2017; Garibaldi et al. 2006), and H. paniculata in Italy (Garibaldi et al. 2018). This study will help in future detection and control to enhance the ornamental value of hydrangeas in Korea.

Severe stem and root rot was found on potted common hydrangeas (Hydrangea macrophylla) in commercial greenhouses in Shimane Prefecture, Japan. Pythium and Globisporangium spp. that were consistently isolated from the plants were identified as Pythium myriotylum, Globisporangium splendens, G. spinosum, and an undescribed species of Globisporangium based on morphological analysis and rDNA-internal transcribed spacer and cox1 gene sequences. All four species reproduced stem and root rot on inoculated potted hydrangea. Plant cultivars significantly differed in their susceptibility to the pathogens. The cultivar Mangekyo was the most susceptible to all the pathogens. [ABSTRACT FROM AUTHOR]

To investigate the effect of steel slag used as substrate on the rooting of Hydrangea macrophylla cuttings, and to develop a new mixed substrate that can partially replace conventional cutting substrates and realize the high-efficient utilization of solid waste, we examined the physical and chemical properties of different mixed substrates containing 10% (T 1 ), 20% (T 2 ), 30% (T 3 ), and 40% (T 4 ) volume fractions of steel slag, and investigated the rooting of H. macrophylla 'Red Beauty' cuttings growing on these substrates, with conventional cutting substrates (peat and perlite) as the control (CK). The results showed that pH value, electrical conductivity, and bulk density of the mixed substrates were significantly higher than those of CK. The aeration porosity of T 2 was higher than other treatments, while the total porosity and water holding porosity differed little from others. Both fresh weight and dry weight of all the four treatments were higher than those of CK, with stem diameter being higher than that of CK (except T 4 ), plant height showing no significant difference compared to CK (except T 4 ), and leaf chlorophyll content being significantly lower than CK. Root length ranked as T 2 >CK>T 1 >T 3 >T 4 , the root surface area and root volume both ranked as T 2 >T 1 >CK>T 4 >T 3 , the root tip ranked as T 2 >CK>T 1 >T 4 >T 3 . Both average root diameter and root activity were significantly higher than that of CK, with the highest value being observed in T 2 . Soluble sugar content in the leaves of T 2 was the highest, followed by T 4 , T 3 , CK, and T 1 . The weight ranking of root growth indices was root activity > average root diameter > root volume > root surface area > root tip number > root length. Redundancy analysis indicated that pH value, electrical conductivity, aeration porosity, and water holding porosity of substrates were key factors influencing root growth and development of cuttings. Our results suggested that substrates mixed with 10% to 40% steel slag could be used for H. macrophylla cutting propagation, and 20% (T 2 ) being the best one because it could significantly improve the survival rate, growth status, and root development of cuttings. Steel slag would be a novel substrate to partially replace conventional unrenewable substrates such as peat and perlite for flower seedling propagation, which could reduce agricultural production cost and provide a high-value utilization way of industry solid waste.

Hydrangea macrophylla has a large inflorescence and rich colors, which has made it one of the most popular ornamental flowers worldwide. Thus far, the molecular mechanism of flower color formation in H. macrophylla flowers is unknown. By comparing the pigment content and transcriptome data of the bud period (FSF1), discoloration period (FSF2) and full-bloom stage (FSF3) of infertile blue flowers of H. macrophylla cv. “Forever Summer,” we found that genes associated with anthocyanin production were most associated with the formation of blue infertile flowers throughout development. The anthocyanin biosynthesis pathway is the main metabolic pathway associated with flower color formation, and the carotenoid biosynthesis pathway appeared to have almost no contribution to flower color. There was no competition between the flavonoid and flavonol and anthocyanin biosynthesis pathways for their substrate. At FSF1, the key genes CHS and CHI in the flavonoid biosynthesis pathway were up-regulated, underlying the accumulation of a substrate for anthocyanin synthesis. By FSF3, the downstream genes F3H, C3′5′H, CYP75B1, DFR, and ANS in the anthocyanin biosynthesis pathway were almost all up-regulated, likely promoting the synthesis and accumulation of anthocyanins and inducing the color change of infertile flowers. By analyzing protein–protein interaction networks and co-expression of transcription factors as well as differentially expressed structural genes related to anthocyanin synthesis, we identified negatively regulated transcription factors such as WER-like, MYB114, and WDR68. Their site of action may be the key gene DFR in the anthocyanin biosynthesis pathway. The potential regulatory mechanism of flower color formation may be that WER-like, MYB114, and WDR68 inhibit or promote the synthesis of anthocyanins by negatively regulating the expression of DFR. These results provide an important basis for studying the infertile flower color formation mechanism in H. macrophylla and the development of new cultivars with other colors.

Vase life is one of the most important factors determining the marketability of cut flowers and influenced by water balance strongly. In recent years, the consumption of hydrangeas as a cut flower has gradually increased. However, the vase life of cut hydrangea flowers is short depends on wilting. Thus, this study was conducted to determine the effects of different treatments [thymol (100, 150 and 200 mgL–1), 8-hydroxyquinoline sulfate (8-HQS) (200 mgL–1)], and their combination with and without 1% sucrose on the vase life, relative fresh weight, daily (solution uptake for 3 days) and total solution uptake of hydrangeas (Hydrangea macrophylla ‘Green Shadow’) harvested freshly. Distilled water was used as the control. Compared to the control, thymol 150 mgL–1 treatment with 1% sucrose significantly increased the vase life of hydrangeas flowers in 5.80 days (from 10.7 to 16.5 days). It was also determined that same treatment increased the total solution uptake and delayed relative fresh weight loss. These results indicated that thymol treatments in combination with sucrose can be used to extend the vase life of cut hydrangea.

Summary: Hydrangea sepals exhibit a wide range of colors, from red, through purple, to blue; the purple color is a color mosaic. However, all of these colors are derived from the same components: simple anthocyanins, 3‐O‐glycosyldelphinidins, three co‐pigment components, acylquinic acids and aluminum ions (Al3+). We show the color mosaic is a result of graded differences in intravacuolar factors.In order to clarify the mechanisms of mosaic color, we performed single‐cell analyses of vacuolar pH, and anthocyanin, co‐pigment and Al3+ content. From the sepals, a protoplast mixture of various colors was obtained. The cell color was evaluated by microspectrophotometry and vacuolar pH then was recorded by using a pH microelectrode. The organic and Al3+ contents were quantified by micro‐HPLC.We found that the bluer the cell, the greater the ratio of 5‐O‐acylquinic acids and Al3+ to anthocyanins. Furthermore, reproducing experiments were conducted by mixing the components under various pH condition; all the colors could be reproduced in the various mixing conditions.Based on the above, we provide experimental evidence for cell color variation in hydrangea. Our study demonstrates the expression of phenotypic differences without any direct genomic control. [ABSTRACT FROM AUTHOR]

Hydrangea macrophylla has a large inflorescence and rich colors, which has made it one of the most popular ornamental flowers worldwide. Thus far, the molecular mechanism of flower color formation in H. macrophylla flowers is unknown. By comparing the pigment content and transcriptome data of the bud period (FSF1), discoloration period (FSF2) and full-bloom stage (FSF3) of infertile blue flowers of H. macrophylla cv. "Forever Summer," we found that genes associated with anthocyanin production were most associated with the formation of blue infertile flowers throughout development. The anthocyanin biosynthesis pathway is the main metabolic pathway associated with flower color formation, and the carotenoid biosynthesis pathway appeared to have almost no contribution to flower color. There was no competition between the flavonoid and flavonol and anthocyanin biosynthesis pathways for their substrate. At FSF1, the key genes CHS and CHI in the flavonoid biosynthesis pathway were up-regulated, underlying the accumulation of a substrate for anthocyanin synthesis. By FSF3, the downstream genes F3H , C3′5′H , CYP75B1 , DFR , and ANS in the anthocyanin biosynthesis pathway were almost all up-regulated, likely promoting the synthesis and accumulation of anthocyanins and inducing the color change of infertile flowers. By analyzing protein–protein interaction networks and co-expression of transcription factors as well as differentially expressed structural genes related to anthocyanin synthesis, we identified negatively regulated transcription factors such as WER-like, MYB114, and WDR68. Their site of action may be the key gene DFR in the anthocyanin biosynthesis pathway. The potential regulatory mechanism of flower color formation may be that WER-like, MYB114, and WDR68 inhibit or promote the synthesis of anthocyanins by negatively regulating the expression of DFR. These results provide an important basis for studying the infertile flower color formation mechanism in H. macrophylla and the development of new cultivars with other colors. [ABSTRACT FROM AUTHOR]