Ground-cover Chrysanthemum Research Articles

RNA-Seq analysis of ground-cover chrysanthemum provides insights into the basis of natural low-temperature stress

RNA-Seq analysis of ground-cover chrysanthemum provides insights into the basis of natural low-temperature stress

High humidity air-impingement blanching (HHAIB) improves drying characteristics and quality of ground-cover chrysanthemum heads

Abstract Effects of high humidity air-impingement blanching (HHAIB) temperature, relative humidity over a range of application time and drying temperature on air-impingement drying kinetics, colour attributes, browning index, blanching weight loss and total flavonoids content of chrysanthemum heads were studied. HHAIB could shorten the drying time of chrysanthemum heads significantly (p < 0.05) by up to 52% compared to the control group without blanching. Meanwhile blanching humidity has a greater influence on drying kinetic than other blanching parameters. D eff values of samples declined first and rose later with the growth of blanching humidity, while increased continuously with the growth of blanching temperature. The highest growth of total flavonoids content can be up to 21.6% under the HHAIB blanching conditions (110 °C of blanching temperature, 45% of relative humidity, 150 s of blanching time) in comparison with the control group. Lightness of all blanched samples was lower than the control group, and redness and total colour difference under different blanching conditions showed significant differences compared to the control group, while no obvious variation was observed in terms of yellowness values.

Breeding of new ground-cover chrysanthemum cultivars with a compact plant architecture and lodging resistance

Breeding of new ground-cover chrysanthemum cultivars with a compact plant architecture and lodging resistance

Selection of optimal reference genes for qRT-PCR analysis of shoot development and graviresponse in prostrate and erect chrysanthemums.

The prostrate cultivars of ground-cover chrysanthemum have been used in landscape gardening due to their small stature, large crown width and strong branching ability. qRT-PCR is a rapid and powerful tool for gene expression analysis, while its accuracy highly depends on the stability of reference genes. The paucity of authentic reference genes presents a major hurdle in understanding the genetic regulators of prostrate architecture. Therefore, in order to reveal the regulatory mechanism of prostrate growth of chrysanthemum stems, here, stable reference genes were selected for expression analysis of key genes involved in shoot development and graviresponse. Based on transcriptome data, eleven reference genes with relatively stable expression were identified as the candidate reference genes. After the comprehensive analysis of the stability of these reference genes with four programs (geNorm, NormFinder, BestKeeper and RefFinder), we found that TIP41 was the most stable reference gene in all of the samples. SAND was determined as a superior reference gene in different genotypes and during the process of shoot development. The optimal reference gene for gravitropic response was PP2A-1. In addition, the expression patterns of LA1 and PIN1 further verified the reliability of the screened reference genes. These results can provide more accurate and reliable qRT-PCR normalization for future studies on the expression patterns of genes regulating plant architecture of chrysanthemums.

EVALUATIONS ON FOUR NEW CULTIVARS OF GROUND-COVER CHRYSANTHEMUM FOR TEA USING ANALYTIC HIERARCHY PROCESS

Ground-cover chrysanthemum (Chrysanthemum morifolium) is one of the most famous flowers in China and landscape species in the world. Traditionally cultivated for ornamental purpose, it is also of a great value for both medicinal and potable uses. For example, chrysanthemum flavored tea is very popular to be used as a relaxant in many areas of China. We define those possessing medicinal and potable functions as ground-cover chrysanthemum for tea (“Dibei Chaju” in Chinese). This study has developed a new model for evaluating new cultivars of Dibei Chaju by Analytic Hierarchy Process. Interpretive Structural Modeling was used for establishing the hierarchy structure of this model. A sensitivity analysis was performed to check the consistency of complementary judgment matrix to minimize possible errors in judgment. According to relative weights for evaluated elements, a quantitative analysis was made. Then, a new evaluation system was established to assess the evaluation model and test its results. Among them, the highest average weight was 0.2865 of production per ha per year, followed by Blooming season and the sub-criteria for medicinal quality; aroma had the lowest weight of 0.0319. ‘Yuren Mian’ was the best cultivar with the highest synthetic score (0.3418), followed by ‘Yuren Long’ (0.2388), and then ‘Fanhua Chulong’ (0.2294), whereas ‘Mao Xiangyu’ got the lowest score (0.1902

Genetic Diversity of Species of Chrysanthemum and Related Genera and Groundcover Cultivars Assessed by Amplified Fragment Length Polymorphic Markers

Chrysanthemums have beautiful flowers with high ornamental value and rich genetic diversity. Amplified fragment length polymorphism (AFLP) markers were used to detect the relationships among 12 wild accessions and 62 groundcover chrysanthemum cultivars. Nineteen EcoRI/MseI primer combinations revealed 452 informative polymorphic bands with a mean of 23.8 bands and 71.5% polymorphic rate per primer pair. Jaccard’s coefficient of similarity varied from 0.64 to 0.89, indicating much genetic variation in chrysanthemums. The 74 accessions were classified into two major groups by unweighted pair group method with the arithmetic averages (UPGMA). The dendrogram showed that AFLP variability was closely correlated with both geographic distribution and traditional classification of the wild accessions. Among all accessions, genetic relationship was the most relevant factor in AFLP-marker clustering, whereas petal type was also informative. AFLP technology could be very efficient for discriminating species of chrysanthemum and its related genera and reconstruct their genetic relatedness.

ESTABLISHMENT OF A REGENERATION SYSTEM FOR THE GENETIC TRANSFORMATION OF GROUND-COVER CHRYSANTHEMUM 'JINDINGHONGXIN'

Ground-cover Chrysanthemum has been used in gardens due to its rich colors, excellent ornamental value. Too much precipitation in summer of north China limits its further use. In order to create chrysanthemum with high resistance to waterlogging, the Vgb (Vitreoscilla hemoglobin) and pmi (phosphomannose isomerase) genes are transferred into the genome of ground-cover chrysanthemum ‘Jindinghongxin’ by Agrobacterium tumefaciens mediated transformation in our research. This research is of profound importance to broaden the usage of ground-cover chrysanthemum in gardens. This research optimized the regeneration system of ‘Jindinghongxin’ including choosing young leaves as explants and the best regeneration culture medium (MS+2.0 mg/L 6-BA+0.5 mg/L NAA), Transformation system for ‘Jindinghongxin’ was established by pre-culturing leaf explants for 2 days. The suitable concentration of Agrobacterium tumefaciens and the suitable dipping time for transformation was OD600=0.4 for 5 minutes. Co-cultivation was done for 2 days at 28°C in the dark after infection and the explants were then put in delayed culture for 4 days. Then the explants were cultured in first selection medium with 6 g/L mannose for 15 days, and then cultured in second selection medium with 7 g/L mannose. Once the regeneration shoot was 1 cm long it was transformed into MS with 350 mg/L carbenicillin for root induction.

Expression profile analysis of genes involved in horizontal gravitropism bending growth in the creeping shoots of ground-cover chrysanthemum by suppression subtractive hybridization

The molecular mechanisms underlying gravitropic bending of shoots are poorly understood and how genes related with this growing progress is still unclear. To identify genes related to asymmetric growth in the creeping shoots of chrysanthemum, suppression subtractive hybridization was used to visualize differential gene expression in the upper and lower halves of creeping shoots of ground-cover chrysanthemum under gravistimulation. Sequencing of 43 selected clones produced 41 unigenes (40 singletons and 1 unigenes), which were classifiable into 9 functional categories. A notable frequency of genes involve in cell wall biosynthesis up-regulated during gravistimulation in the upper side or lower side were found, such as beta tubulin (TUB), subtilisin-like protease (SBT), Glutathione S-transferase (GST), and expensing-like protein (EXP), lipid transfer proteins (LTPs), glycine-rich protein (GRP) and membrane proteins. Our findings also highlighted the function of some metal transporter during asymmetric growth, including the boron transporter (BT) and ZIP transporter (ZT), which were thought primarily for maintaining the integrity of cell walls and played important roles in cellulose biosynthesis. CmTUB (beta tubulin) was cloned, and the expression profile and phylogeny was examined, because the cytoskeleton of plant cells involved in the plant gravitropic bending growth is well known.

Mapping single-locus and epistatic quantitative trait loci for plant architectural traits in chrysanthemum

Plant architecture is important for chrysanthemum cultivation and breeding. To determine the genetic basis of plant architectural traits in chrysanthemum, a population of 142 F1 plants derived from a cross between the creeping ground-cover chrysanthemum cultivar Yuhualuoying and the erect potted cultivar Aoyunhanxiao was used to detect quantitative trait loci (QTL) associated with plant height, plant width, inter-node length and flower neck length. The broad-sense heritability hB2 for the four plant architectural traits ranged from 0.33 to 0.83, and transgressive segregation was observed. Single-locus QTL analysis revealed a total of five QTL, accounting for 6.0–16.1% of the phenotypic variation. Additionally, 11 pairs of epistatic QTL were identified, explaining 3.5–14.5% of the phenotypic variations. The majority of the interactions detected occurred between background loci. These results indicate that both additive and epistatic effects contribute to phenotypic variation in the plant architecture of chrysanthemum. It is expected that the identified markers associated with the additive QTL and epistatic QTL detected in this study will be of importance in future breeding programs to develop chrysanthemum cultivars exhibiting desirable plant architecture.

CgDREBa transgenic chrysanthemum confers drought and salinity tolerance

The drought and salinity tolerances of a creeping ground-cover chrysanthemum variety ‘Yuhuaxunzhang’ were compared to the performance of its two derived transgenic lines carrying a drought-responsive element binding (DREB) factor from chrysanthemum designated as CgDREBa. The over-expression of CgDREBa conferred a measure of tolerance to both stresses. The transgenic lines showed a higher survival rate and were better able to retain fresh weight in the presence of stress. Activities of superoxide dismutase and peroxidase and the proline content were all higher in the leaves of the transgenic plants after a prolonged period of stress, but they accumulated less malondialdehyde. CgDREBa appears to function as a transcription activator of genes within the oxidative and osmotic homeostasis transduction pathways, and represents a promising candidate for a biotechnological approach to improve the level of abiotic stress tolerance in plants.

Effect of Nitric Oxide and Hydrogen Peroxide on Adventitious Root Development from Cuttings of Ground-Cover Chrysanthemum and Associated Biochemical Changes

It is well known that plant adventitious root formation can be stimulated by the application of nitric oxide (NO) and hydrogen peroxide (H2O2) exogenously but the mechanism of this physiological response is still unclear. Ground-cover chrysanthemum (Dendranthema morifolium ‘Beiguozhicun’) was used to understand the effects of NO and H2O2 on the rooting of plant cuttings and the associated biochemical changes of the rooting zone during the rhizogenesis process. The results showed that the effect of NO or H2O2 on rooting of ground-cover chrysanthemum cuttings was dose-dependent, with a maximal biological response at 50 μM of NO donor sodium nitroprusside (SNP) or 200 μM H2O2. There was a synergistic effect between NO and H2O2 on mediating rooting. NO and H2O2 treatments at the proper dosage might increase the activities of polyphenol oxidase (PPO) and indoleacetic acid oxidase (IAAO) and the content of water-soluble carbohydrate (WSC) and total nitrogen, while decreasing the total polyphenol content of ground-cover chrysanthemum cuttings. In addition, rooting percentage was significantly correlated with these biochemical constituent activities or contents. Together, these results indicated that NO and H2O2 treatments enhanced adventitious root development synergistically and independently by stimulating the activities of PPO and IAAO enzymes and the content of carbohydrate and nitrogen and simultaneously repressing the production of polyphenol.

Anatomical structure and gravitropic response of the creeping shoots of ground-cover chrysanthemum ‘Yuhuajinhua’

The chrysanthemum cultivar ‘Yuhuajinhua’ has a creeping habit. The anatomy and distribution of amyloplasts within ‘Yuhuajinhua’ stems were compared to those typical of non-creeping cultivars. ‘Yuhuajinhua’ stems are similar to those of conventional cultivars; but except for the pith, the proportion of the various tissues present in the upper side of stems was higher than that in the lower side. Most of the amyloplasts lie in the centre of the endodermal cells of the ‘Yuhuajinhua’ stems, rather than at the bottom, as is typical for non-creeping cultivars. When ‘Yuhuajinhua’ plants were oriented horizontally and kept in the dark, the stems retained their original growth direction, and the endodermis amyloplasts sedimented according to the gravitational direction. The endodermis amyloplasts responded rapidly to gravistimulation. The content of IAA in the upper side of the ‘Yuhuajinhua’ stems was higher than that in the lower side, associated with the assymetric growth of the stems.

Heterologous expression of the AtDREB1A gene in chrysanthemum increases drought and salt stress tolerance

DNA cassette containing an AtDREB1A cDNA and a nos terminator, driven by a cauliflower mosaic 35S promoter, or a stress-inducible rd29A promoter, was transformed into the ground cover chrysanthemum (Dendranthema grandiflorum) 'Fall Color' genome. Compared with wild type plants, severe growth retardation was observed in 35S:DREB1A plants, but not in rd29A:DREB1A plants. RT-PCR analysis revealed that, under stress conditions, the DREB1A gene was over-expressed constitutively in 35S:DREB1A plants, but was over-expressed inductively in rd29A:DREB1A plants. The transgenic plants exhibited tolerance to drought and salt stress, and the tolerance was significantly stronger in rd29A:DREB1A plants than in 35S:DREB1A plants. Proline content and SOD activity were increased inductively in rd29A:DREB1A plants than in 35S:DREB1A plants under stress conditions. These results indicate that heterologous AtDREB1A can confer drought and salt tolerance in transgenic chrysanthemum, and improvement of the stress tolerance may be related to enhancement of proline content and SOD activity.

Expression of the Arabidopsis DREB1A gene in transgenic chrysanthemum enhances tolerance to low temperature

SummaryThe gene DREB1A, encoding a stress-inducible transcription factor, driven by the cauliflower mosaic virus 35S (CaMV) promoter or by the stress-inducible rd29A promoter, was transferred into chrysanthemum plants [Dendranthema grandiflorum (Ramat.) Kitamura] cv. ‘Fall Color’ by Agrobacterium-mediated transformation. Integration of the target gene, DREB1A was confirmed by PCR and Southern blotting. When exposed to 2°C, expression of DREB1A was enhanced in the roots of young transgenic 35S:DREB1A plant lines, and induced in transgenic rd29A:DREB1A lines. Electrolyte leakage in leaves of rd29A:DREB1A plant lines was significantly lower than in 35S:DREB1A lines. Compared to control plants, superoxide dismutase activities and proline contents increased slowly in transgenic plants at the start of the cold stress treatment and remained at high levels during later periods, especially in rd29A:DREB1A transgenic lines. Young plants of the rd29A:DREB1A line could tolerate –8°C for 12 h, with a survival rate of 37.5%. No survival was observed in 35S:DREB1A lines or in wild-type plants. These results indicate that a combination of the stress-inducible rd29A promoter and the DREB1A gene enhanced the tolerance of ground-cover chrysanthemum plants to cold stress through a transgenic approach.

Fast breeding of ground-cover chrysanthemum

The experiment of tissue culture of ground-cover chrysanthemum with the tip of shoots as the expiant was made. On MS medium, with adding BA 3.0 mg/ L and NAA 0.01 mg / L, the adventitious buds had the best multiplication result. The best result for taking roots was obtained on 1 / 2 MS medium with adding NAA 0.1 mg/ L. It had good result and a high survival rate for transplanting the young test-tube plants into soil when they were 3–4 cm high, with 5–7 rootlets (0.5–1.0 cm in length). 30% of edible powdered sugar was used to replace sucrose in order to lower the cost and the same results were obtained.