RESUMEN
MicroRNAs (miRNAs) play important roles in the regulation of gene expression by post-transcriptionally targeting mRNAs for cleavage or translational repression. miR168 is a key miRNA because it regulates the expression of the slicer protein ARGONAUTE1 (AGO1), which catalyzes mRNA cleavage. Interestingly, plant miR168s are highly evolutionarily conserved; however, it is unclear whether MIR168 promoter elements and expression patterns are also conserved. Here, we isolated MIR168 promoters from monocot rice and dicot grape genomes. To determine the expression pattern, different promoters were fused to a beta-glucoronidase reporter gene and the resulting constructs were then transformed in Arabidopsis. The results revealed clear differences in the MIR168 promoter sequence of monocot and dicot plant species. Moreover, the pattern of MIR168 promoter expression differed between monocots and dicots. These results suggest that, unlike that of miR168, the MIR168 promoter is not conserved in monocots and dicots.
Asunto(s)
Proteínas de Arabidopsis/biosíntesis , Arabidopsis/genética , Proteínas Argonautas/biosíntesis , MicroARNs/genética , Oryza/genética , Proteínas de Arabidopsis/genética , Proteínas Argonautas/genética , Evolución Molecular , Regulación de la Expresión Génica de las Plantas , Genoma de Planta , Regiones Promotoras Genéticas , Vitis/genéticaRESUMEN
Aquaporins play a direct role in plant water relation under salt stress, but the effects of 5-aminolevulinic acid (ALA) on aquaporin gene expression in salt-treated plants remain unknown. This study investigated the potential effects of exogenous ALA (50 mg/dm3) on aquaporin expression levels under salt stress (75 mM NaCl) in the salt-sensitive (Jinchun No.4) and the relatively salt-tolerant cucumber (Jinyou No.1) seedlings. The expressions of cucumber PIP aquaporin gene (CsPIP1:1) and cucumber NIP aquaporin gene (CsNIP) were analyzed in 20-day-old seedling leaves at 2, 4, 8, 16, and 24 h after ALA treatment. After treatment with saline alone and ALA alone, CsPIP1:1 and CsNIP gene expression levels in the 2 cucumber cultivars increased to maximum at 2 h. The aquaporin gene expression in salt-treated cucumber seedling leaves was considerably higher than that in leaves subjected to exogenous ALA. Further, the aquaporin expression levels in Jinchun No.4 were higher than those in Jinyou No.1, reaching 5.20- and 2-fold induction levels, respectively. After treatment with both ALA and NaCl, the CsNIP gene expression was downregulated in both the cucumber cultivars, while that of CsPIP1:1 decreased at 2 h and then increased to 3.8-fold in Jinchun No.4. In Jinyou No.1, CsPIP1:1 gene expression gradually increased to 2.3-fold at 4 h, followed by a decline in expression. The results indicated that ALA might delay and counteract the upregulated expression of CsPIP1:1 and CsNIP genes in cucumber seedlings under NaCl stress. Thus, salt tolerance of cucumber seedlings might be enhanced by ALA application.
Asunto(s)
Acuaporinas/biosíntesis , Cucumis sativus/genética , Proteínas de Plantas/biosíntesis , Estrés Fisiológico/genética , Ácido Aminolevulínico/farmacología , Cucumis sativus/crecimiento & desarrollo , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Hojas de la Planta/efectos de los fármacos , Hojas de la Planta/genética , Raíces de Plantas/efectos de los fármacos , Raíces de Plantas/genética , Salinidad , Tolerancia a la Sal/genética , Plantones/genética , AguaRESUMEN
Constitutive promoters have been widely used in crop biotechnology applications. Tissue-specific or inducible promoters, however, have advantages in some cases. We isolated the 731-bp 5' flanking sequence of a potato (Solanum tuberosum) gene, encoding ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) activase (RCA), which was isolated by genome walking. By using GUS as a reporter and with Northern blot analysis, the 702-bp fragment (referred to as StRCAp), ranging from nt -731 to -30 relative to the initiation code of the RCA gene, was analyzed in transgenic tobacco plants. The activity of StRCAp in leaves was 0.4-fold less than that of cauliflower mosaic virus 35S promoter, and was expressed throughout the green part of the light-grown transgenic T(1) seedlings, including cytoledons, leaves and young stems, but not roots. Further deletion analysis revealed that a shorter fragment (nt -249 to -30, StRCAp2) retained light-inducible features in cytoledons and leaves, but showed no detectable activity in young stems and roots. Although the activity of StRCAp2 in leaves was reduced significantly compared with that of StRCAp, the overall data indicated that cis-elements sufficient to regulate organ-specific and light-inducible transcription are within the 220-bp fragment. There is potential for application of StRCAp in plant genetic engineering.
Asunto(s)
Proteínas de Plantas/genética , Plantas Modificadas Genéticamente/genética , Regiones Promotoras Genéticas , Solanum tuberosum/genética , Secuencia de Bases , Northern Blotting , Caulimovirus/genética , Regulación de la Expresión Génica de las Plantas , Genes Reporteros , Datos de Secuencia Molecular , Hojas de la Planta/genética , Proteínas de Plantas/biosíntesis , Raíces de Plantas/genética , Tallos de la Planta/genética , Análisis de Secuencia de ADN , Solanum tuberosum/enzimología , Nicotiana/genéticaRESUMEN
Worldwide comparison of Toxoplasma gondii isolates from free-range chickens ( Gallus domesticus ) has indicated that T. gondii isolates from Brazil are phenotypically and genetically different from isolates from other countries; most strains from Brazil are pathogenic to mice, there is great genetic variability, most isolates are nonclonal, and Type II is absent or rare. The prevalence of T. gondii in 50 free-range chickens from the island of Fernando de Noronha, Brazil (this island is 350 km from the mainland) was determined. Antibodies to T. gondii were assayed by the modified agglutination test (MAT); 42 (84%) chickens had titers of 1ratio5 in 2, 1ratio10 in 4, 1ratio20 in 3, 1ratio40 in 6, 1ratio80 in 6, 1ratio160 in 5, 1ratio320 in 3, and 1ratio640 or higher in 13 chickens. Hearts of 40 seropositive chickens were bioassayed individually in mice. Toxoplasma gondii was isolated from 24 chickens with MAT titers of 1ratio5 or higher; the isolates were designated TgCKBr210-233. None of the isolates was pathogenic for mice. The restricted fragment length polymorphism using 10 markers revealed 6 genotypes, including the Type II, Type III, and 4 new chicken genotypes (#59-#62) that were different from genotypes so far reported in Brazil. All 24 isolates were successfully genotyped; 15 isolates were Brazil chicken type #59, 1 type #60, 1 type #61, 1 type #62; 5 were Type II (with Type I allele at the Apico locus); and 1 isolate was clonal Type III. Results in this study indicate that T. gondii on this island consists of unique genotypes as well as clonal genotypes that are dominant in Europe and North America.