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In this study, five cultivars of cut chrysanthemum Chrysanthemum×morifolium Ramat., 'Jinba', 'Yuuka', 'Fenguiren', 'Xueshen', and 'Huangjin' were used to explore the functions of 5-azacytidine (5-azaC) on chrysanthemum growth and flower development. The results showed that 5-azaC had different effects on the growth of the five cultivars during in vitro culture. The final statistics showed that low concentrations promoted plant growth, whereas high concentrations inhibited growth; however, each cultivar had different growth curves, demonstrating that 5-azaC had no consistent inhibitory actions on growth. On the basis of the squaring time and flowering time statistics, we found that 5-azaC had a certain effect on the flowering time of all cut chrysanthemums, and all of these cultivars showed extremely early strains. Summer chrysanthemum ('Yuuka', 'Fenguiren', 'Xueshen', and 'Huangjin') treatments led to both early and delayed flowering. When the statistics were analyzed for different individuals, we found that the treatments shortened the squaring time in early-flowering plants. In 'Jinba', an autumn chrysanthemum, the treatment helped broken juvenile limitations and allowed plants to undergo photoperiod induction in the early stage. Additionally, we also determined the flower diameter differences in these treatments; ray florets from 'Yuuka' and 'Huangjin' trended to show tubular florets, and the location of tubular and ray florets were changed in 'Xueshen' capitulum. In conclusion, on the basis of flowering time in five early varieties of cut chrysanthemum, we propose that 5-azaC may regulate the methylation level of genes that control flower induction and flower development. These results provide phenotypic data and material for exploring the function of DNA methylation in regulating flowering. [ABSTRACT FROM AUTHOR]

Although some species that accumulate only cyanidin (Cy) in nature can produce blue flowers through iron ions, there has been no evidence of blue chrysanthemums being generated in this manner. This study revealed that flavonoid extracts from the ray florets of the chrysanthemum cultivar 'Wandai Fengguang' turned blue when exposed to Fe3+. Samples that could turn blue were labeled as CB (Cy-determined blue flowers), while samples that did not turn blue were labeled as CN (Cy-determined non-blue flowers). After a series of experiments, a stable screening system was established using flavonoid extracts containing NaAc buffer at pH 5.5 and a total anthocyanin concentration (TAC) of 30 μmol.L-1, and the addition of Fe3+ from 0 to 0.25 μmol.L-1 allowed for the selection of five CB samples from 39 chrysanthemum cultivars. All five CB samples exhibited flower color phenotypes that belonged to Cluster-I with redness (a)) values ranging from 29.03 to 45.99, yellowness (b)) values from -11.31 to 3.77, and brightness (L)) values from 29.07 to 45.99. Additionally, the ratio of TAC to total luteolin concentration (TLC) was found to be a critical factor for distinguishing between CB and CN samples. To realize the desired blue hue in the flavonoid extracts with the participation of Fe3+, a TAC to TLC ratio of 2.25 and above is required. Moreover, the protoplasts and ray florets of CB samples that turned blue with the involvement of Fe2+ showed great potential for cultivating blue chrysanthemums through ferriceanthocyanin chelate. Overall, this study reveals that blue flowers can be cultivated through the increase in the iron ion concentration, combined with the accumulation of Cy. [ABSTRACT FROM AUTHOR]

Background: Roses are important plants for human beings with pivotal economical and biological traits like continuous flowering, flower architecture, color and scent. Due to frequent hybridization and high genome heterozygosity, classification of roses and their relatives remains a big challenge. Results: Here, to identify potential markers for phylogenetic reconstruction and to reveal the patterns of natural selection in roses, we generated sets of high quality and comprehensive reference transcriptomes for Rosa chinensis ‘Old Blush’ (OB) and R. wichuriana ‘Basye’s Thornless’ (BT), two species exhibiting contrasted traits of high economical importance. The assembled reference transcriptomes showed transcripts N50 above 2000 bp. Two roses shared about 10,073 transcripts (N50 = 2282 bp), in which a set of 5959 transcripts was conserved within genera of Rosa. Further comparison with species in Rosaceae identified 4447 transcripts being common (Rosaceae-common) in Rosa, Malus, Prunus, Rubus, and Fragaria, while a pool of 164 transcripts being specific for roses (Rosa-specific). Among the Rosaceae-common transcripts, 409 transcripts showed a signature of positive selection and a clustered expression in different tissues. Interestingly, nine of these rapidly evolving genes were related to DNA damage repair and responses to environmental stimulus, a potential associated with genome confliction post hybridization. Coincident with this fast evolution pattern in rose genes, 24 F-box and four TMV resistant proteins were significantly enriched in the Rosa-specific genes. Conclusions: We expect that these Rosaceae-common and Rosa-specific transcripts should facilitate the phylogenetic analysis of Rosaceae plants as well as investigations of Rosa-specific biology. The data reported here could provide fundamental genomic tools and knowledge critical for understanding the biology and domestication of roses and for roses breeding. [ABSTRACT FROM AUTHOR]

The large-flowered Chinese chrysanthemum is one of the most morphologically complex ornamental plants, and its identification and classification requires a welldefined and reproducible system. The diversity of the capitulum is determined mainly by multiple shapes of ray florets. However, the existing classification systems for ray floret types are incomplete and unsystematic. In this study, 299 ray florets from 151 large- flowered chrysanthemum varieties in China, as well as 12 related traits of ray florets, were selected for quantitative classification. First, as one of the most important indices of ray floret shape, the corolla tube merged degree (CTMD) was defined as the corolla tube length/ray floret length (CTL/RFL). Combined with a probability grading method and linear regression analysis, the CTMD was divided into three groups, flat, spoon, and tubular, of which the CTL/RFL ranged from 0 to 0.20, 0.20 to 0.60, and 0.60 to 1.00, respectively. Second, Q-mode cluster analysis indicated that each group could be further categorized into three types (straight, curved, and atypical), based on other important variables in the ray floret. Finally, the ray floret was classified into nine types, including flat-straight, flat-curve, flat-atypical, spoon-straight, spoon-curve, spoon-atypical, tubular-straight, tubular-curve, and tubular-atypical. This ray floret classification system will be valuable in the classification of capitulum shape and has significance for the identification, breeding, and international standardization of chrysanthemum cultivars. [ABSTRACT FROM AUTHOR]

Conventional crossbreeding remains an effective technique for chrysanthemum (Chrysanthemum ×morifolium Ramat.) breeding. However, there are always many problems when breeding chrysanthemum because of its complex genetic background, such as difficulty matching parents, selecting superior hybrid progenies, quantitatively describing certain target traits, and evaluating breeding results. A recent mathematical analysis method is an effective method for evaluating plant breeding progress. In this study, we used 505 multiflora chrysanthemum germplasm resources as test materials; we divided the flowering time into five groups using a grading analysis method, including extremely early group (genotypes that flowered when daylength was longer than 13.5 hours), early group (genotypes that flowered when daylength was 13.5-12.0 hours), medium group (genotypes that flowered when daylength was 12.0-11.0 hours), late group (genotypes that flowered when daylength was 11.0-10.0 hours), and extremely late group (genotypes that flowered when daylength was shorter than 10.0 hours). Moreover, the breeding objective was to breed early-flowering genotypes. Using 15 phenotypic characters as evaluation factors, 37 excellent genotypes, including four early-flowering genotypes, were screened out from the aforementioned resources according to an analytic hierarchy process (AHP) and weighting of the gray relational grade. We selected one early-flowering genotype and eight medium-flowering genotypes from these 37 genotypes and matched six hybridized combinations based on the genetic distance between genotypes calculated by theQcluster analysis method.Weused a comprehensive evaluation method combining AHP and the gray relational analysis (GRA) method for the evaluation of 367 progenies. Moreover, we screened out 52 superior hybrids, including 36 early-flowering hybrids. The results of this study demonstrate that the mathematical analysis method is an immensely effective method to breed new cultivars of early-flowering multiflora chrysanthemum. This study also provides an effective method to define and improve the flowering time of other cultivated plants. [ABSTRACT FROM AUTHOR]

Background: The flower colour of agricultural products is very important for their commercial value, which is mainly attributed to the accumulation of anthocyanins. Light is one of the key environmental factors that affect the anthocyanin biosynthesis. However, the deep molecular mechanism remains elusive, and many problems regarding the phenotypic change and the corresponding gene regulation are still unclear. In the present study, Chrysanthemum x morifolium 'Purple Reagan', a light-responding pigmentation cultivar, was selected to investigate the mechanism of light-induced anthocyanin biosynthesis using transcriptomic analyses. Results: Only cyanidin derivatives were identified based on the analyses of the pigmentation in ray florets. Shading experiments revealed that the capitulum was the key organ and that its bud stage was the key phase responding to light. These results were used to design five libraries for transcriptomic analyses, including three capitulum developmental stages and two light conditions. RNA sequences were de novo assembled into 103,517 unigenes, of which 60,712 were annotated against four public protein databases. As many as 2,135 unigenes were differentially expressed between the light and dark libraries with 923 up-regulated and 1,212 down-regulated unigenes in response to shading. Next, interactive pathway analysis showed that the anthocyanin biosynthetic pathway was the only complete metabolic pathway both modulated in response to light and related to capitulum development. Following the shading treatment, nearly all structural genes involved in the anthocyanin biosynthetic pathway were down-regulated. Moreover, three CmMYB genes and one CmbHLH gene were identified as key transcription factors that might participate in the regulation of anthocyanin biosynthesis under light conditions based on clustering analysis and validation by RT-qPCR. Finally, a light-induced anthocyanin biosynthesis pathway in chrysanthemums was inferred. Conclusion: The pigmentation of the ray florets of chrysanthemum cultivar 'Purple Reagan' is dependent on light. During the light-induced pigmentation process, the expression of seven structural genes in the anthocyanin biosynthetic pathway (regulated by at least four transcription factors in response to light) are the main contributors to the pigmentation of chrysanthemums. This information will further our understanding of the molecular mechanisms governing light-induced anthocyanin biosynthesis in ornamental plants. [ABSTRACT FROM AUTHOR]

Abstract: Chrysanthemum lavandulifolium (Fisch. ex Trautv.) Makino is a halophyte species that belongs to the Asteraceae family, and the genus Chrysanthemum. It is one of the ancestors of C. × morifolium Ramatella. Understanding the tolerance mechanism associated with salt stress in C. lavandulifolium could provide important information for explaining the salt tolerance of higher plants and could also help enhancing breeding programs of cultivated Chrysanthemum. In this study, cDNA amplified fragment length polymorphism (cDNA-AFLP) was used to detect differential gene expression in leaves of C. lavandulifolium in response to NaCl treatment. The determination of membrane permeablility, peroxidase activity (POD), malon-dialdehyde (MDA), as well as proline and leaf chlorophyll contents under different NaCl concentrations showed that a 200mM NaCl treatment was an optimal condition for the cDNA-AFLP experiment. Using this concentration during different times (0, 3h, 12h, 24h and 48h), we obtained 1930 cDNA fragments using 64 primers. After sequencing 234 randomly chosen cDNA clones and BLASTx analyzing, we got 129 expressed sequence tags (ESTs) which had no significant homology with other sequences, 85 ESTs were homologous to genes with known functions, whereas the rest of ESTs showed homology to unclassified or putative proteins. 25 ESTs that were similar to known functional genes involved in several abiotic and biotic stresses were confirmed by semi-quantitative RT-PCR and qRT-PCR. The expression patterns of these salt-responsive genes not only responded to salt stress but also to plant hormones, such as abscisic acid (ABA), and to other abiotic stresses such as drought and cold. These results indicate an extensive cross-talk among several stresses. Our results provide interesting information for further understanding the molecular mechanisms of salt tolerance in C. lavandulifolium. [Copyright &y& Elsevier]

Chrysanthemum (Chrysanthemum × morifolium) is one of the most important ornamental plants in the world. They are typically used as cut flowers or potted plants. Chrysanthemum can exhibit red, purple, pink, yellow and white flowers, but lack bright red and blue flowers. In this study, we identified two chrysanthemum cultivars, C × morifolium ‘LPi’ and C × morifolium ‘LPu’, that only accumulate flavonoids in their ligulate flowers. Next, we isolated seven anthocyanin biosynthesis genes, namely CmCHS, CmF3H, CmF3’H, CmDFR, CmANS, CmCHI and Cm3GT in these cultivars. RT-PCR and qRT-PCR analyses showed that CmF3′H was the most important enzyme required for cyanidin biosynthsis. To rebuild the delphinidin pathway, we downregulated CmF3’H using RNAi and overexpressed the Senecio cruentus F3′5′H (PCFH) gene in chrysanthemum. The resultant chrysanthemum demonstrated a significantly increased content of cyanidin and brighter red flower petals but did not accumulate delphinidin. These results indicated that CmF3′H in chrysanthemum is important for anthocyanin accumulation, and Senecio cruentus F3′5′H only exhibited F3′H activity in chrysanthemum but did not rebuild the delphinidin pathway to form blue flower chrysanthemum. [ABSTRACT FROM AUTHOR]