Histone H3K4 methyltransferase DcATX1 promotes ethylene induced petal senescence in carnation

Petal senescence is controlled by a complex regulatory network. Epigenetic regulation like histone modification influences chromatin state and gene expression. However, involvement of histone methylation in regulating petal senescence is still largely unknown. Here, we found that the trimethylation of histone H3 at Lysine 4 (H3K4me3) is increased during the ethylene induced petal senescence in carnation (Dianthus caryophyllus L.). The H3K4me3 levels are positively associated with the expression of transcription factor DcWRKY75, ethylene biosynthetic genes DcACS1 and DcACO1, and senescence associated genes (SAGs) DcSAG12 and DcSAG29. Further, we identified that carnation DcATX1 (ARABIDOPSIS HOMOLOG OF TRITHORAX1) encodes a histone lysine methyltransferase which can methylate H3K4. Knockdown of DcATX1 delays ethylene induced petal senescence in carnation, which is associated with the downregulated expression of DcWRKY75, DcACO1 and DcSAG12. While overexpression of DcATX1 exhibits the opposite effects. DcATX1 promotes the transcription of DcWRKY75, DcACO1 and DcSAG12 by targeting to their promoters to elevate the H3K4me3 levels. Overall, our results demonstrate that DcATX1 is a H3K4 methyltransferase that promotes the expression of DcWRKY75, DcACO1 and DcSAG12 by regulating H3K4me3 levels, thereby accelerating ethylene induced petal senescence in carnation. This study further indicates that epigenetic regulation is important for plant senescence process.

Efficient Plant Regeneration via Indirect Organogenesis in Carnation (Dianthus Caryophyllus Semperflorens flore pleno) Cultivars

ABSTRACT Callus induction and plant regeneration are important steps of in vitro plant breeding of ornamental plants. In this study, the effects of different combinations of plant growth regulators (PGRs), promoters, and minerals on callus induction and plant regeneration in different carnation cultivars were studied in a completely randomized design with three replications. For callus induction, 16 different combinations of 2,4-dichlorophenoxyacetic acid (2,4-D), 6-benzylaminopurine (BA), 1-naphthaleneacetic acid (NAA), and casein hydrolysate (CH) were studied using in vitro leaf explants. The Murashige and Skoog (MS) medium supplemented with 0.2 mg·dm-3 of 2,4-D and 200 mg·dm-3 of CH showed the highest frequency of callus induction. Among the cultivars, ‘Noblesse’ showed the highest rate of callus induction (91.67%). Regarding regeneration, BA, NAA, silver nitrate (AgNO3), and adenine hemisulfate (As) were used in ten different combinations. The ‘Cameron’, ‘Tabasco’, and ‘Noblesse’ cultivars with 95.24% regeneration percentage showed the highest rate of plant regeneration. Generally, in most cultivars, the highest regeneration rate and shoot number per explant were found in the MS medium supplemented with 3 mg·dm-3 of BA, 0.6 mg·dm-3 of NAA, 5 mg·dm-3 of AgNO3, and 40 mg·dm-3 of As. According to the results, the highest regeneration frequency was obtained when 40 mg·dm-3 of As was added to the medium. Finally, the flow cytometry analysis indicated that there were no significant differences between in vitro regenerated and control plants in terms of DNA ratios.

Cadmium Uptake and Growth Responses of Seven Urban Flowering Plants: Hyperaccumulator or Bioindicator?

The application of flowering plants is the basis of urban forest construction. A newly-found flowering hyperaccumulator is crucial for remediating urban contaminated soil sustainably by cadmium (Cd). This study evaluated growth responses, Cd uptake and bioaccumulation characteristics of seven urban flowering plants. Based on growth responses of these plants, Calendula officinalis L. showed high tolerance to at least 100 mg kg−1 Cd, in terms of significant increase in biomass and with no obvious changes in height. After 60 d exposure to 100 mg kg−1 Cd, the accumulated Cd in shoots of the plant reached 279.51 ± 13.67 μg g−1 DW, which is above the critical value defined for a hyperaccumulator (100 μg g−1 DW for Cd). Meanwhile, the plant could accumulate Cd to as much as 926.68 ± 29.11 μg g−1 DW in root and 1206.19 ± 23.06 μg g−1 DW in plant, and had higher Cd uptake and bioaccumulation values. According to these traits, it is shown that Calendula officinalis L. can become a potential Cd-hyperaccumulator for phytoremediation. By contrast, Dianthus caryophyllus L. is very sensitive to Cd stress in terms of significantly decreased biomass, height and Cd uptake, indicating the plant is considered as a Cd-bioindicator.

Extending vase life of carnation flowers by postharvest nano silver, humic acid and Aloe Vera gel treatments

Standard Carnation flowers (Dianthus caryophyllus cv. Dover) were harvested at the paint brush stage in the early morning, pre-cooled at 4° C for 6-h then moved under dry conditions to the laboratory. Flowers were weighted and treated for 24-h with silver nanoparticles (AgNPs) at 0, 5 or 10 ppm in plastic buckets. After pulsing treatments, cut flowers were transferred to 500 mL glass jars containing 300 mL of preservation solution treatments including, individually, humic acid at 200, 400 or 600 ppm and Aloe vera gel at 2.5%, 5.0% or 7.5% (w/v) till the end of the experiment (when flower color began to fade, petals began to roll). Distilled water was used for the control and to prepare the tested solutions. 2% sucrose was added to all treatments including the control. Addition of all preservatives to vase solutions significantly increased all the studied characteristics of cut flowers compared to control (distilled water, least values). Nanosilver treatments have the potential to be used as preservative solutions for improving postharvest vase life and quality of carnation flowers. An increment in vase life, relative fresh weight, vase solution uptake, flower diameter as well as total chlorophylls in leaves, total carbohydrates and total phenols in leaves and petals was observed, in addition to a decrease in bacterial counts in vase solution. Best results were obtained using 5 ppm AgNPs + 5.0% Aloe vera gel followed by 5 ppm AgNPs +7.5% Aloe vera gel solutions. Aloe vera gel, especially 5.0% level, showed better results than humic acid when used alone or combined with AgNPs. Nanosilver at 5 ppm recorded better results than 10 ppm when used as a single treatment.

Typification of 14 names in the Dianthus virgineus group (Caryophyllaceae)

The nomenclature of 14 taxa from Central and Southern Europe within the Dianthus virgineus group is discussed. Dianthus aggericola Jord., D. collivagus Jord., D. consimilis Jord., D. orophilus Jord., D. saxicola Jord., D. juratensis Jord. are here lectotypified by specimens from the Jordan herbarium in LY, while D. godronianus Jord. by a specimen in P. Dianthus subacaulis Vill. is neotypified by a specimen collected on Mont Ventoux (S. France) and housed in MPU. For D. sylvestris Wulfen, a lectotype is here designated and its previous neotypification is discussed. Dianthus caryophyllus var. tenuifolius Moris, D. caryophyllus f. minor Moris and D. sylvestris var. garganicus Ten. are lectotypified by specimens housed in herbarium Moris (TO) and herbarium Tenore (K). Dianthus virgineus var. tergestinus Rchb. is lectotypified by a drawing from the Icones florae Germanicae & Helveticae, while D. contractus var. evolutus Lojac. is neotypified by a specimen in P. For each taxon the currently accepted name is provided including new synonymies. The type indication is followed by nomenclatural and taxonomic notes, in which the original material found is commented and the reasons for the identification of the types are discussed.

An Effective Protocol for Carnation (Dianthus caryophyllus L.) cv. 'Geolei' Explants Sterilization for Successful Callusing and Shoot Regeneration

Carnation is a popular floricultural crop grown widely for its attractive cut flowers. Micro-propagation can be used to create large-scale carnation output. For growth and development, plants require some necessary nutrients as well as growth regulators. Due to the importance of carnation, the present work is carried out using leaf and nodal segments to examine the potential of several plant growth regulators for in vitro callus formation and adventitious shoot regeneration. Explants were sterilized properly with bavistin, sodium hypochlorite and mercuric chloride. The minor contaminated cultures were created by consecutively treating the explants with 0.25% bavistin, 0.50% sodium hypochlorite, and 0.1% mercuric chloride for ten, fifteen, and two minutes. MS media with 2.5 mg/l 2,4-dichlorophenoxy acetic acid (2,4-D) in combination with 0.75 mg/l naphthalene acetic acid (NAA) resulted in the maximum callus induction (90.47%) from leaf explants. Maximum shoots (76.47%) were produced in MS media supplemented with 2.0 mg/l Thidiazuron (TDZ) + 0.25 mg/l NAA. NAA at 1.25 mg/l was most efficient for maximum root induction (83.32%). In the present study, an effective protocol of carnation explants sterilization was optimized for successful callusing and shoot regeneration.