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Salvia miltiorrhiza (commonly known in China as Danshen) is widely used in traditional Chinese medicine, and it is applied in the treatment of many diseases, particularly cardiovascular disease. Commercial propagation of Danshen is carried out either through seed germination or in vitro regeneration (micropropagation). However, it is not clear if the different propagation methods affect the chemical properties of the derived plants. In the present study, we first established a highly efficient tissue culture system for Danshen propagation. The addition of 1.0 mg·L−1 6-benzyladenine (BA) and 0.1 mg·L−1 α-naphthalene acetic acid (NAA) to Murashige and Skoog (MS) medium was optimal for inducing adventitious shoots; the highest rate of rooting was recorded on MS medium with 0.2 mg·L−1 NAA, on which the survival rate of transplanted plantlets was 95%. Next, we assessed antioxidant properties in the different tissues of plants of the same age, derived from micropropagation or seed germination, and measured tanshinone, total phenol, and total flavonoid contents. Our results showed that tissues of micropropagated plantlets had higher antioxidant activities than tissues of seed-derived plantlets; the micropropagated plantlets also had higher tanshinone contents in their roots. Thus, a rapid and efficient micropropagation system was established for Danshen, and it can be used for cultivating this plant to obtain therapeutic compounds.
Cytokinins play an important role in regulating plant growth and development. The cytokinin gene, isopentenyl transferase (ipt), was placed under the control of the ACC oxidase promoter from the LEACO1 gene from Lycopersicon esculentum and introduced into Nicotiana tabacum (cv. Havana) and chrysanthemum (Dendranthema × grandiflorum `Iridon'). Transformants were confirmed by PCR reaction and Southern blot and analyzed for phenotypical changes under both greenhouse and growth chamber conditions. With both species, LEACO1-ipt transgenic plants displayed a wide range of vegetative and generative phenotypes. With plants growing in the vegetative state, some LEACO1-ipt transgenic lines appeared similar to the non-transgenic wild-type cultivars while other lines showed excessive lateral branch development and short internodes. With plants grown under generative conditions, several LEACO1-ipt transgenic lines showed a 2 to 10-fold increase in the number of flower buds relative to the wild-type cultivars. With chrysanthemum, dramatic increases in bud count were observed on transgenic lines that otherwise displayed a morphology similar to the non-transgenic lines. Analysis of ipt expression indicated a marked change in gene expression between the most extreme phenotypes observed in this study. LEACO1-ipt lines that express normal vegetative development but increased flower bud counts appear to have great potential for ornamental crop improvement.
Seasonal deacclimation was investigated during Jan. to Mar. 2014 in leaves of 10 azalea cultivars (Rhododendron section Tsutsusi) under natural conditions in eastern China. Based on the midwinter leaf freezing tolerance (LFT), these cultivars were grouped as “more-hardy” vs. “less-hardy.” Eight of the 10 cultivars first showed deacclimation when daily mean temperature over 2-week period preceding the LFT measurement was ≈9.5 °C. Deacclimation for other two cultivars was somewhat delayed and might have involved deacclimation–reacclimation cycling before eventual deacclimation. Our data indicate that the “more-hardy” group deacclimated slower than the “less-hardy” ones over the first half of the deacclimation period. This trend reversed during the second half of the deacclimation period. Accordingly, “more-hardy” and “less-hardy” cultivars depicted a “curvilinear” and “reverse curvilinear/linear” deacclimation kinetics. “More-hardy” cultivars generally had higher total soluble sugars (TSS) than “less-hardy” ones at acclimated state. TSS declined during deacclimation in all cultivars, and the loss was positively correlated with the loss in LFT. Leaf starch content generally followed opposite trend to that of TSS, i.e., it was at lowest during acclimated state and increased during deacclimation.
Abstract results showed that many germplasms of P. Armeniaca. P. persica and a few germplasms of P. Salicina had immersed into those of P. mume. Some cultivars (strains) possessed species characteristics coming from 2 or 3 of the 3 species in a single plant. All of the plants tested were transition types of the related varieties such as var. bungo and so on. Some new characteristics of P. mume were found in a few strains. The resources were classified into highly, mediumly and lightly backcrossed types. The mean yield index and fruit weight of highly back-crossed type (HB) were significantly higher than those of the other 2 types. The setting rate of HB was higher and significantly higher than that of lightly and mediumly type, respectively. There were no significant differences in mean bitter index and flower index among them.
Salvia splendens is a widely used ornamental bedding plant; however, the limited propagation method has decreased its quality and yield. Through years of selection, we have obtained a new variety of S. splendens with weak apical dominance and named it as ‘Cailinghong’. To establish an effective method for regeneration of S. splendens ‘Cailinghong’, different explants, including leaves, receptacles, petioles, stem nodes, and stem segments were used for adventitious bud induction. Next, various combinations of plant growth regulators (PGRs) were selected for bud and root induction, which were assessed by adventitious bud initiation rate and proliferation rate, as well as root induction rate. Meanwhile, the survival rate of transplanted plantlets was also calculated. As a result, stem nodes were found easy to be induced to form buds, and the optimum medium component was 1/2 Murashige and Skoog (MS) medium supplemented with 0.45 µM naphthalene acetic acid (NAA), 8.88 µM 6-benzylaminopurine (6-BA), and 2.46 µM 3-indolebutyric acid (IBA) for plantlets induction, whereas 1/4 MS medium supplemented with 2.23 µM NAA for root induction. Furthermore, the survival rate of transplanted plantlets was up to 80%, and all regenerated plantlets were normal in phenotype. Therefore, cultured in 1/2 MS medium with combined PGRs, whole plantlet of S. splendens ‘Cailinghong’ could be regenerated directly from stem node.
To explore the reasons for seed abortion in southern China fresh-eating jujube, improve its reproductive biology, and provide a theoretical basis for the crossbreeding of jujube, we carried out self-pollination and cross-pollination experiments with Ziziphus jujuba Mill. ‘Zhongqiusucui’ as the female parent. We observed the process of pollen tube growth in pistil and embryo development by fluorescence microscopy and paraffin section methods. The results show there were self- and cross-incompatibilities during pollination and fertilization, and there were no significant differences in pollen germination and pollen tube growth between self-pollination and cross-pollination. It took at least 4 hours for pollen and stigma to recognize each other, 6 hours for pollen to germinate on the stigma, and 12 hours for the pollen tube to penetrate the mastoid cells of the stigma. After 48 hours of pollination, the pollen tube reached one third of the style. The pollen tube remained stagnant 72 to 120 hours after pollination, and remained at one third of the stylar canal. Simultaneously, the pollen tubes on the stigma twisted and interacted with each other, and expanded into a spherical shape. A few pollen tubes reached the ovary and completed fertilization. However, some early globular embryos degenerated before forming into globular embryos and resulted in the formation of empty embryo sacs, which leads to seed abortion. In conclusion, the poor pollination and fertilization, and the blocked development of the embryo resulted in seed abortion in Z. jujuba ‘Zhongqiusucui’.
A 920 bp fragment of the ACC oxidase gene promoter from tomato (LEACO1) was used to drive GUS gene expression. The LEACO1 0.92kb fragment contained two stress-responsive short motifs; a 10 bp TCA motif (5'-TCATCTTCTT-3') twice (allowing two substitutions) and an 8 bp element (5'-AA/TTTCAAA-3') once. The TCA motif is found in over 30 stress- and pathogen-inducible genes while the 8 bp element is necessary for ethylene-response in the carnation GST1 and the tomato E4 gene promoters. Previously in chrysanthemum, cytokinin regulation with LEACO1 0.92kb produced dramatic increases in lateral branching and bud initiation. Tobacco plants carrying LEACO1 0.92kb –GUS were used to examine the response of the LEACO1 0.92kb promoter to various hormones and hormone inhibitors. GUS activity in LEACO1 0.92kb –GUS plants was detected in leaves and stems, but not roots. High expression was detected in shoots with the apical bud intact, but GUS activity decreased with the apical bud removed. Applying IAA to the shoot apex after removing the apical bud, restored GUS activity. However, the IAA transport inhibitor TIBA reduced GUS activity in shoots with intact apical buds, and in IAA-treated shoots with excised buds. In shoots with excised apical buds, GUS activity increased when the ethylene precursor ACC was applied, but decreased in intact shoots when the ethylene biosynthesis inhibitor AOA was applied. These data suggest that auxins produced in the apical meristem are capable of regulating LEACO1 0.92kb activity, probably through auxin-induced ethylene biosynthetic pathway activity.
Creeping bentgrass (Agrostis stolonifera var. palustris Huds.) is desirable as a putting green turfgrass in the transition zone as a result of year-round green color, ball roll, and playability. However, management challenges exist for bentgrass greens, including winter temperature fluctuations. Frosts often cause cancellations or delays of tee time resulting in lost revenue. In response to this winter golf course management issue, a research project was initiated at Clemson University from 1 Dec. 2005 and 2006 to 1 Aug. 2006 and 2007 on a ‘L93’ creeping bentgrass putting green to determine the impacts of foot traffic or mower traffic and time of traffic application on bentgrass winter performance. Treatments consisted of no traffic (control), foot traffic, and walk-behind mower traffic (rolling) at 0700 and 0900 hr when canopy temperatures were at or below 0 °C. Foot traffic included ≈75 steps within each plot using size 10 SP-4 Saddle Nike golf shoes (soft-spiked sole) administered by a researcher weighing ≈75 kg. A Toro Greensmaster 800 walk-behind greens mower weighing 92 kg with a 45.7-cm roller was used for rolling traffic. Data collected included canopy and soil temperatures (7.6 cm depth), visual turfgrass quality (TQ), clipping yield (g·m−2), shoot chlorophyll concentration (mg·g−1), root total nonstructural carbohydrates (TNC) (mg·g−1), soil bulk density (g·cm−3), and water infiltration rates (cm·h−1). Time and type of traffic significantly influenced bentgrass winter performance. On all TQ rating dates, 0700 hr rolling traffic decreased TQ by ≈1.1 units compared with foot traffic at 0700 hr. In December, regardless of traffic application time, rolling traffic reduced bentgrass shoot growth ≈17%. However, in February, chlorophyll, soil bulk density, and water infiltration differences were not detected. By the end of March, all treatments had acceptable TQ. Root TNC was unaffected in May, whereas shoot chlorophyll concentrations were unaffected in May and August. This study indicates bentgrass damage resulting from winter traffic is limited to winter and early spring months and full recovery should be expected by summer.