Tomato (Lycopersicon esculantum) ASR1 (abscisic acid stress ripening protein), a small plant-specific protein whose cellular mode of action defies deduction based on its sequence or homology analyses, is one of numerous plant gene products with unknown biological roles that become over-expressed under water- and salt-stress conditions. Steady-state cellular levels of tomato ASR1 mRNA and protein are transiently increased following exposure of plants to poly(ethylene glycol), NaCl or abscisic acid. Western blot and indirect immunofluorescence analysis with anti-ASR1 antibodies demonstrated that ASR1 is present both in the cytoplasmic and nuclear subcellular compartments; approx. one-third of the total ASR1 protein could be detected in the nucleus. Nuclear ASR1 is a chromatin-bound protein, and can be extracted with 1 M NaCl, but not with 0.5% Triton X-100. ASR1, overexpressed in Escherichia coli and purified to homogeneity, possesses zinc-dependent DNA-binding activity. Competitive-binding experiments and SELEX (systematic evolution of ligands by exponential enrichment) analysis suggest that ASR1 binds at a preferred DNA sequence.
SummaryAdducin is a cytoskeletal protein that can function in vitro to bundle F-actin and to control the assembly of the F-actin/spectrin cytoskeletal network. The Drosophila Adducin-like (Add) locus (also referred to as hu-li tai shao (hts)) encodes a family of proteins of which several are homologous to mammalian adducin (Ding et al., Proc. Natl. Acad. Sci. USA90, 2512–16, 1993; Yue & Spradling, Genes Dev.6, 2443–54, 1992). We report the identification of two novel adducin isoforms: a 95 × 103Mr form (ADD-95) and an 87 × 103Mr form (ADD-87). We present a detailed analysis of the distribution patterns of ADD-95 and ADD-87 during oogenesis and embryogenesis. The isoforms are co-expressed in several cell- and tissuetypes; however, only ADD-87 is present in mid- to late-stage oocytes. ADD-87 is present throughout the oocyte cortex at stages 9 and 10 of oogenesis but is detectable only at the anterior pole from stage 11 onward, correlated with localisation of Add-hts mRNA first to the cortex and then to the anterior pole of the oocyte. ADD-87 co-localises with F-actin and spectrin in the cortex of the oocyte through stage 10 of oogenesis, consistent with a possible role in cytoskeletal assembly or function predicted by mammalian studies.
BackgroundVernalization is an obligatory requirement of extended exposure to low temperatures to induce flowering in certain plants. It is the most important factor affecting flowering time and quality in Easter lily (Lilium longiflorum). Exposing the bulbs to 4 °C gradually decreases flowering time up to 50 % compared to non-vernalized plants. We aim to understand the molecular regulation of vernalization in Easter lily, for which we characterized the global expression in lily bulb meristems after 0, 2, 5, 7 and 9 weeks of incubation at 4 °C.ResultsWe assembled de-novo a transcriptome which, after filtering, yielded 121,572 transcripts and 42,430 genes which hold 15,414 annotated genes, with up to 3,657 GO terms. This extensive annotation was mapped to the more general GO slim plant with a total of 94 terms. The response to cold exposure was summarized in 6 expression clusters, providing useful patterns for dissecting the dynamics of vernalization in lily. The functional annotation (GO and GO slim plant) was used to group transcripts in gene sets. Analysis of these gene sets and profiles revealed that most of the enriched functions among genes up-regulated by cold exposure were related to epigenetic processes and chromatin remodeling. Candidate vernalization genes in lily were selected based on their sequence similarity to known regulators of flowering in other species.ConclusionsWe present a detailed analysis of gene expression dynamics during vernalization in Lilium, covering several time points and accounting for biological variation by the use of replicates. The resulting collection of transcripts and novel isoforms provides a useful resource for studying the changes occurring during vernalization at a fine level. The selected potential candidate genes can shed light on the regulation of this process.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-015-1675-1) contains supplementary material, which is available to authorized users.
The antiviral activity of plant ethanol extracts against Herpes Simplex Virus-1 and -2 (HSV-1 and HSV-2) and Varicella-Zoster Virus (VZV) was investigated in vitro. Ficus binjamina, resistant to plant viruses, and Lilium candidum, which has a high susceptibility to plant viruses were used. Leaf extracts of F. binjamina inhibited all studied viruses, while its fruit extracts inhibited only VZV. L. candidum leaf extracts had no effect on VZV but strongly inhibited HSV-1 and slightly HSV-2. None of the extracts showed significant cytotoxic effect on uninfected Vero cells even at a concentration of 250 microg/ml (CC(50)>400 microg/ml). The greatest antiviral effect was obtained when extracts were added to cells at the time of infection, whereas a partial inhibitory effect was observed when they were added post-infection. There was indirect evidence for strong interactions between the plant extracts and the viruses and weak interactions with the cell surface.
Floral induction in Tulipa gesneriana and Lilium longiflorum is triggered by contrasting temperature conditions, high and low temperature, respectively. In Arabidopsis, the floral integrator FLOWERING LOCUS T (FT), a member of the PEBP (phosphatidyl ethanolamine-binding protein) gene family, is a key player in flowering time control. In this study, one PEBP gene was identified and characterized in lily (LlFT) and three PEBP genes were isolated from tulip (TgFT1, TgFT2 and TgFT3). Overexpression of these genes in Arabidopsis thaliana resulted in an early flowering phenotype for LlFT and TgFT2, but a late flowering phenotype for TgFT1 and TgFT3. Overexpression of LlFT in L. longiflorum also resulted in an early flowering phenotype, confirming its proposed role as a flowering time-controlling gene. The tulip PEBP genes TgFT2 and TgFT3 have a similar expression pattern in tulip, but show opposite effects on the timing of flowering in Arabidopsis. Therefore, the difference between these two proteins was further investigated by interchanging amino acids thought to be important for the FT function. This resulted in the conversion of phenotypes in Arabidopsis upon overexpressing the substituted TgFT2 and TgFT3 genes, revealing the importance of these interchanged amino acid residues. Based on all obtained results, we hypothesize that LlFT is involved in creating meristem competence to flowering-related cues in lily, and TgFT2 is considered to act as a florigen involved in the floral induction in tulip. The function of TgFT3 remains unclear, but, based on our observations and phylogenetic analysis, we propose a bulb-specific function for this gene.
During the year 2002, two new diseases with unknown etiologies were detected in cucurbit crops in Israel. One disease was detected in squash fields throughout the country, while the second appeared in a single watermelon plot in the south, just outside the city of Elat. The infected watermelon plot was eradicated, but nonetheless the new disease spread throughout the country and today it is present in all the watermelon production areas. Both diseases were associated with elevated whitefly populations. Indeed, it was found that both are transmitted only by whiteflies, and are incited by two begomoviruses. Both viruses were cloned and sequenced, and were identified as Watermelon chlorotic stunt virus (WmCSV) and Squash leaf curl virus (SLCV). The host range of the Israeli WmCSV isolate (WmCSV-IL) was determined and resembles the host range of the three other known WmCSV isolates (from Yemen, Sudan, and Iran), but with a few differences. Although no genetic resistance to WmCSV was observed in cultivated watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai], resistance to the virus was found in a wild relative, colocynth (Citrullus colocynthis (L) Schrader). Nucleotide sequence comparisons revealed that WmCSV-IL is highly homologous to other WmCSV isolates, with the highest homology (nearly identical) to the isolate from Sudan. SLCV-IL host range was determined as well, and was also found to be similar to other SLCV isolates. However, following genome sequencing, it was found that due to two separate point mutations, two viral open reading frames (ORF) were altered. The AC2 ORF was extended by 129 nucleotides, while the BV1 ORF was reduced by 99 nucleotides.
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