Arabidopsis thaliana thylakoid lumen 18.3 kDa protein (TLP18.3) gene (At1g54780) has a domain of unknown function, which is a family of uncharacterized protein. To examine the developmental regulation of this gene, Arabidopsis thaliana TLP18.3 T-DNA insertion mutant (SALK_109618) and wild type plant were observed for the effect of ABA, NaCl and mannitol on the germination of seeds.  50 mM NaCl inhibit more germination rate in mutant plants than wild type plants followed by 0.1 µM ABA and 20 mM mannitol. But in control condition also mutant plants have less (54%) germination rate than the wild type plant which having germination (77%). Arabidopsis thaliana TLP18.3 T-DNA insertion mutant plants (SALK_109618)  have shown 6-9 days of flowering delay but after  Agrobacterium mediated transformation of Arabidopsis thaliana TLP18.3 T-DNA insertion mutant with pPZP200GB-TLP18.3 construct rescued the flowering delay and germination. The translational analysis have shown that the TLP18.3 protein accumulation wild type plant of Arabidopsis thaliana and it was not detected in western blot analysis of Arabidopsis thaliana TLP18.3 T-DNA insertion mutant demonstrated that this protein was absent in mutant plants. For the subcellular localization of Arabidopsis thaliana TLP18.3, the protoplast of transformed Arabidopsis thaliana TLP18.3 T-DNA insertion mutant after Agrobacterium mediated transformation with pPZP200GB-TLP18.3 construct which is having GFP green fluorescence image, which was completely overlapped with red autoflorescence of chloroplast image clearly showed the chloroplast localization of TLP18.3.

[ES]Tesis sobre "Caracterizaci?n funcional de nuevos componentes moleculares implicados en la se?alizaci?n del ?cido absc?sico (ABA) durante la germinaci?n de semillas de Arabidopsis thaliana" | [EN]Thesis on "Functional characterization of new molecular components involved in signaling abscisic acid (ABA) during germination of Arabidopsis thaliana"

The regulatory role of more active brassinosteroids - brassinolide in seedling development in darkness was studied. The growth parameters and photosynthetic pigment content of Arabidopsis thaliana seedlings under differ light conditions were investigated. The plant model to study regulatory role of selective light and brassinosteroids are Arabidopsis thaliana. A. thaliana ecotype Columbia (Col) and det2 mutant with disturbed synthesis of brassinolide were used. The plant grow parameters depending on the brassinolide concentration. Physiological activity of green light also blue light in the regulation of Arabidopsis seedling development was noted. The interaction between plant development program - skoto- or photomorphogenesis and endogenous level of brassinosteroids has been shown.

Selenium has been proved as an essential micronutrient and is beneficial to animals and humans. It is a structural component of the important antioxidant enzyme, glutathione peroxidase, which catalyzes reactions to detoxify reactive oxygen species. However, the essentiality of Se in plants remains controversial and the protective role of Se in plants has rarely been investigated. In this study, Arabidopsis thaliana was grown in controlled environments having selenate or selenite enriched medium, and the effects of Se on plant growth, Se distribution and Se species were investigated. The 60Co gamma facility was used as the gamma radiation source to facilitate oxidative stress in plant. A sequential extraction procedure including an enzymatic digestion step was developed for the fractionation of different Se species in Arabidopsis. High performance liquid chromatography interfaced with inductively coupled plasma mass spectrometry (HPLC-ICP/MS) was selected for the separation and speciation of Se using anion exchange and reversed phase. From the observed results, gamma irradiation and higher medium Se concentrations were toxic to the plants, but irradiated plants treated with 25μM selenate were shown to be protected. Selenate was transported and distributed mainly in plant leaf while selenite was located in plant roots in higher amounts. The anion exchange chromatogram showed that selenomethionine (SeMet) was the dominant organic Se species in both selenate and selenite treated plants. Selenate was the second most abundant Se form in selenate treated plants; a certain amount of selenite was detected in selenite treated plants but it was converted to SeMet readily. A small amount of Se-methylselenocysteine was found in all the Se enriched plants. Due to instrumental problems, only few Se species were identified using reversed phase.

fwa is a late flowering epi-mutant in Arabidopsis thaliana. FWA is silenced by DNA methylation in vegetative tissue but is demethylated in the central cell of the female ovule and continues to be expressed in the endosperm from the maternal copy. FWA is stably silenced in A. thaliana, but in related Arabidopsis species, FWA expression and DNA methylation levels vary in vegetative tissue. In this study, we show that variation in FWA expression in field isolates having identical DNA sequences is associated with changes in DNA methylation and may change over time. Vegetative FWA expression is correlated with decreased methylation at non-CG sites in the region upstream of the transcription start site in species related to A. thaliana and we conclude that methylation of this region is critical for FWA silencing in these species. In A. thaliana, FWA expression is affected by methylation in regions both upstream and downstream of the transcription start site. Ectopic A. thaliana FWA expression causes a late flowering phenotype, but over-expression of Arabidopsis lyrata FWA does not. In A. thaliana, stable silencing of FWA to prevent late flowering may have evolved through the selection of large tandem repeats and spread of the critical methylated region to include these repeats.

[Objective] The aim was to better research the function and action mode of High Mobility Group B (HMGB) proteins in higher plants. [Method] At2G33450, At5G23405 and At5G23420 genes of HMGB protein family in Arabidopsis thaliana were cloned by the use of RT-PCR method, and the expression of these three proteins in E.coli and Arabidopsis thaliana were detected by using SDS-PAGE, Northern blot and subcellular localization methods. [Result] The results showed that the molecular weights of the three proteins were 17.5, 17.0 and 27.0 kD respectively, and the expression levels of the proteins in Arabidopsis thaliana were At5G23420＞At5G23405＞At2G33450. In addition, all the three proteins were located in nucleus. [Conclusion] The study will provide a basis for the further research on the biological function of HMGB proteins in higher plants.

Terpenes constitute the largest class of plant secondary (or specialized) metabolites, which are compounds of ecological function in plant defense or the attraction of beneficial organisms. Using biochemical and genetic approaches, nearly all Arabidopsis thaliana (Arabidopsis) enzymes of the core biosynthetic pathways producing the 5-carbon building blocks of terpenes have been characterized and closer insight has been gained into the transcriptional and posttranscriptional/translational mechanisms regulating these pathways. The biochemical function of most prenyltransferases, the downstream enzymes that condense the C₅-precursors into central 10-, 15-, and 20-carbon prenyldiphosphate intermediates, has been described, although the function of several isoforms of C₂₀-prenyltranferases is not well understood. Prenyl diphosphates are converted to a variety of C₁₀-, C₁₅-, and C₂₀-terpene products by enzymes of the terpene synthase (TPS) family. Genomic organization of the 32 Arabidopsis TPS genes indicates a species-specific divergence of terpene synthases with tissue- and cell-type specific expression profiles that may have emerged under selection pressures by different organisms. Pseudogenization, differential expression, and subcellular segregation of TPS genes and enzymes contribute to the natural variation of terpene biosynthesis among Arabidopsis accessions (ecotypes) and species. Arabidopsis will remain an important model to investigate the metabolic organization and molecular regulatory networks of terpene specialized metabolism in relation to the biological activities of terpenes.