Plant regeneration and genetic transformation of C. canadensis: a non-model plant appropriate for investigation of flower development in Cornus (Cornaceae).

KEY MESSAGE : Efficient Agrobacterium -mediated genetic transformation for investigation of genetic and molecular mechanisms involved in inflorescence architectures in Cornus species. Cornus canadensis is a subshrub species in Cornus, Cornaceae. It has recently become a favored non-model plant species to study genes involved in development and evolution of inflorescence architectures in Cornaceae. Here, we report an effective protocol of plant regeneration and genetic transformation of C. canadensis. We use young inflorescence buds as explants to efficiently induce calli and multiple adventitious shoots on an optimized induction medium consisting of basal MS medium supplemented with 1 mg/l of 6-benzylaminopurine and 0.1 mg/l of 1-naphthaleneacetic acid. On the same medium, primary adventitious shoots can produce a large number of secondary adventitious shoots. Using leaves of 8-week-old secondary shoots as explants, GFP as a reporter gene controlled by 35S promoter and hygromycin B as the selection antibiotic, a standard procedure including pre-culture of explants, infection, co-cultivation, resting and selection has been developed to transform C. canadensis via Agrobacterium strain EHA105-mediated transformation. Under a strict selection condition using 14 mg/l hygromycin B, approximately 5 % explants infected by Agrobacterium produce resistant calli, from which clusters of adventitious shoots are induced. On an optimized rooting medium consisting of basal MS medium supplemented with 0.1 mg/l of indole-3-butyric acid and 7 mg/l hygromycin B, most of the resistant shoots develop adventitious roots to form complete transgenic plantlets, which can grow normally in soil. RT-PCR analysis demonstrates the expression of GFP transgene. Green fluorescence emitted by GFP is observed in transgenic calli, roots and cells of transgenic leaves under both stereo fluorescence microscope and confocal microscope. The success of genetic transformation provides an appropriate platform to investigate the molecular mechanisms by which the various inflorescence forms are developed in Cornus plants.

In vivo and in vitro animal investigation of the effect of a mixture of herbal extracts from Tribulus terrestris and Cornus officinalis on penile erection.

INTRODUCTION: Herbal preparations have long been used as folk remedies for erectile dysfunction (ED). AIM: This study examined the effects of Tribulus terrestris and Cornus officinalis extracts on relaxation of the smooth muscle of the corpus cavernosum (CC), their mechanisms of action, and the effects of oral administration of a mixture of the herbal extracts on penile erection. METHODS: The relaxation effects and the mechanisms of action of T. terrestris extract, C. officinalis extract, and the mixture of both extracts on the rabbit CC were investigated in an organ bath. To evaluate whether the relaxation response of the CC shown in an organ bath occurs in vivo, intracavernous pressure (ICP) was calculated in rats after oral administration for a month. Additionally, adenosine 3',5'-cyclic monophosphate (cAMP) and guanosine 3', 5'-cyclic monophosphate (cGMP) in the CC were measured using immunoassay. MAIN OUTCOME MEASURES: Smooth muscle relaxation was expressed as the percent decrease in precontraction induced by phenylephrine. ICP was assessed in rats after the oral administration of a mixture of both extracts for 1 month and changes in cGMP and cAMP concentrations were measured based on the concentration of the mixture of both extracts. RESULTS: T. terrestris extract, C. officinalis extract, and the mixture of both extracts showed concentration-dependent relaxation effects of the CC. In both the endothelium-removed group and N(G)-nitro-L-arginine methyl ester pretreatment group, T. terrestris extract inhibited relaxation. ICP measured after oral administration of the extract mixture for a month was higher than that measured in the control group, and a significant increase in cAMP was observed in the mixture group. CONCLUSIONS: T. terrestris extract and C. officinalis extract exhibited concentration-dependent relaxation in an organ bath. In the in vivo study of the extract mixture, ICP and cAMP was significantly potentiated. Accordingly, the mixture of T. terrestris extract and C. officinalis extract may improve erectile function.

Botany: a record-breaking pollen catapult.

The release of stored elastic energy often drives rapid movements in animal systems, and plant components employing this mechanism should be able to move with similar speed. Here we describe how the flower stamens of the bunchberry dogwood (Cornus canadensis) rely on this principle to catapult pollen into the air as the flower opens explosively. Our high-speed video observations show that the flower opens in less than 0.5 ms--to our knowledge, the fastest movement so far recorded in a plant.

Photoperiodic regulation of a 24-kD dehydrin-like protein in red-osier dogwood (Cornus sericea L.) in relation to freeze-tolerance.

A predominant 24-kD dehydrin-like protein was previously found to fluctuate seasonally within red-osier dogwood (Cornus sericea L.) stems. The current study attempted to determine what environmental cues triggered the accumulation of the 24-kD protein and to assess its potential role in winter survival. Controlled photoperiod and field studies confirmed that photoperiod regulates a reduction of stem water content (SWC), freeze-tolerance enhancement and accumulation of the 24-kD protein. Diverse climatic ecotypes, which are known to respond to different critical photoperiods, displayed differential reduction of SWC and accumulation of the 24-kD protein. A time-course study confirmed that prolonged exposure to short days is essential for SWC reduction, 24-kD protein accumulation, and freeze-tolerance enhancement. Water deficit induced 24-kD protein accumulation and enhanced freeze-tolerance under long-day conditions. In all instances, freeze-tolerance enhancement and 24-kD protein accumulation was preceded by a reduction of SWC. These results are consistent with the hypothesis that C. sericea responds to decreasing photoperiod, which triggers a reduction in SWC. Reduced SWC in turn may trigger the accumulation of the 24-kD protein and a parallel increase in freeze-tolerance.