Phalaenopsis flowering locus VE regulates floral organ maturation.

KEY MESSAGE: PaFVE is low ambient temperature-inducible and acts as a systemic regulator in the early stage of floral development in Phalaenopsis. Phalaenopsis aphrodite: subsp. formosana, a native orchid species of Taiwan, is an economically important ornamental crop that requires low ambient temperature for floral transition. Currently, limited genetic information about such orchid species hampers genetic manipulation for specific or improved floral traits, and the control of flowering time independent of temperature regulation. In this study, the sequence of the full-length of Phalaenopsis flowering locus VE (PaFVE) gene was determined. Spatial and temporal expression studies showed that mRNA transcripts of PaFVE were inducible by low ambient temperature, and high levels of expression occurred after spiking initiation and remained high throughout the early stage of floral development. Further investigation revealed that floral organ development was impeded in PaFVE-silenced P. aphrodite, but flowering time and floral organogenesis were not compromised. Analysis of the downstream flowering genes suggested that the delay in floral maturation is associated with a corresponding decrease in the expression of downstream flowering genes, PaSOC1, PaSOC1L and PaAGL24. The ectopic expression of PaFVE in Arabidopsis resulted in an accelerated flowering time, accompanied by an increase in the expression of AtSOC1, thus revealing the functional role of PaFVE as a floral regulator. Overall, our results demonstrate that PaFVE has evolutionarily diverged and conserved functions, and serves as a regulator of floral organ maturation in Phalaenopsis and a regulator of flowering time in Arabidopsis.

MSRB7 reverses oxidation of GSTF2/3 to confer tolerance of Arabidopsis thaliana to oxidative stress.

Methionine sulfoxide reductases (MSRs) catalyse the reduction of oxidized methionine residues, thereby protecting proteins against oxidative stress. Accordingly, MSRs have been associated with stress responses, disease, and senescence in a taxonomically diverse array of organisms. However, the cytosolic substrates of MSRs in plants remain largely unknown. Here, we used a proteomic analysis strategy to identify MSRB7 substrates. We showed that two glutathione transferases (GSTs), GSTF2 and GSTF3, had fewer oxidized methionine (MetO) residues in MSRB7-overexpressing Arabidopsis thaliana plants than in wild-type plants. Conversely, GSTF2 and GSTF3 were highly oxidized and unstable in MSRB7-knockdown plants. MSRB7 was able to restore the MetO-GSTF2M100/104 and MetO-GSTF3M100 residues produced during oxidative stress. Furthermore, both GSTs were specifically induced by the oxidative stress inducer, methyl viologen. Our results indicate that specific GSTs are substrates of MSRs, which together provide a major line of defence against oxidative stress in A. thaliana.

Arabidopsis root-abundant cytosolic methionine sulfoxide reductase B genes MsrB7 and MsrB8 are involved in tolerance to oxidative stress.

Excess reactive oxygen species (ROS) accumulation under various environmental stresses can damage intracellular polysaccharides, DNA, lipids and proteins. Methionine sulfoxide reductase (MSR) participates in a protein repair system that is one of the defensive mechanisms that diminishes oxidative destruction. In Arabidopsis, cytosolic MsrB7 and MsrB8 are oxidative stress-inducible protein repair enzymes that are abundant in the root. Here methyl viologen (MV) treatment was demonstrated to increase greatly the accumulation of H(2)O(2) in MsrB7-knockdown, MsrB8-knockdown and wild-type Arabidopsis, but not in transgenic plants overexpressing MsrB7 or MsrB8. The reduction in H(2)O(2) level under MV treatment in these overexpressing plants coincided with increased activity of glutathione S-transferase (GST), a herbicide-detoxifying enzyme. MsrB7 and MsrB8 are suggested to play an important role in defense against oxidative stress. Transgenic plants overexpressing MsrB7 or MsrB8 were viable and survived after MV and H(2)O(2) treatment. Ectopic expression of specific cytosolic MsrB genes may be useful for application in crop improvement.

Tape-Arabidopsis Sandwich - a simpler Arabidopsis protoplast isolation method.

BACKGROUND: Protoplasts isolated from leaves are useful materials in plant research. One application, the transient expression of recombinant genes using Arabidopsis mesophyll protoplasts (TEAMP), is currently commonly used for studies of subcellular protein localization, promoter activity, and in vivo protein-protein interactions. This method requires cutting leaves into very thin slivers to collect mesophyll cell protoplasts, a procedure that often causes cell damage, may yield only a few good protoplasts, and is time consuming. In addition, this protoplast isolation method normally requires a large number of leaves derived from plants grown specifically under low-light conditions, which may be a concern when material availability is limited such as with mutant plants, or in large scale experiments. RESULTS: In this report, we present a new procedure that we call the Tape-Arabidopsis Sandwich. This is a simple and fast mesophyll protoplast isolation method. Two kinds of tape (Time tape adhered to the upper epidermis and 3 M Magic tape to the lower epidermis) are used to make a "Tape-Arabidopsis Sandwich". The Time tape supports the top side of the leaf during manipulation, while tearing off the 3 M Magic tape allows easy removal of the lower epidermal layer and exposes mesophyll cells to cell wall digesting enzymes when the leaf is later incubated in an enzyme solution. The protoplasts released into solution are collected and washed for further use. For TEAMP, plasmids carrying a gene expression cassette for a fluorescent protein can be successfully delivered into protoplasts isolated from mature leaves grown under optimal conditions. Alternatively, these protoplasts may be used for bimolecular fluorescence complementation (BiFC) to investigate protein-protein interactions in vivo, or for Western blot analysis. A significant advantage of this protocol over the current method is that it allows the generation of protoplasts in less than 1 hr, and allows TEAMP transfection to be carried out within 2 hr. CONCLUSION: The protoplasts generated by this new Tape-Arabidopsis Sandwich method are suitable for the same range of research applications as those that use the current method, but require less operator skill, equipment and time.

[Being personal: the development of community psychiatric mental health nursing].

Community psychiatric mental health nursing care emphasizes humanistic values and focuses on serving patient and family needs. In Taiwan, such care is delivered largely as part of patient discharge care plans and hospital / community based service models. Issues involved underscore the importance of operating an effective and integrated transfer system, the role and function of nurses and training in relevant competencies (Shiau, Huang & Lin, 2005). This article again emphasizes the importance of 'being personal' in the development of community psychiatric mental health nursing in Taiwan. Critical issues to consider include humanization, empowerment, nursing competencies, regulations, relating on a personal level, and facilitating empowerment and enlightenment on the healing process.