No abstract

Transgenic tobacco plants that express the genome-linked protein/proteinase-coding region of the potyvirus tobacco vein mottvlngirus (TVMV) were produced and tested for their reaction to inoculation with TVMV and two other potyviruses. Fig. 1).For the CP gene, the PCR-amplified DNA was ethanolprecipitated, digested with Nco I and Sst I, and purified by preparative agarose gel electrophoresis. The resulting fragment was cloned as an Nco I-Sst I fragment into a plasmid (pBS-AlMV5') containing the 5'-untranslated region of AIMV RNA 4. This resulting plasmid had the general structure 5'-Xho I-AIMV RNA 4 5'-untranslated region-Nco I-CP gene-Sst I. The Xho I-Sst I fiagment of this was cloned into pKYLX71:35S2 (see Fig. 1).

This paper reviews the importance, prospective and development of synthetic promoters reported in planta. A review of the synthetic promoters developed in planta would help researchers utilize the available resources and design new promoters to benefit fundamental research and agricultural applications. The demand for promoters for the improvement and application of transgenic techniques in research and agricultural production is increasing. Native/naturally occurring promoters have some limitations in terms of their induction conditions, transcription efficiency and size. The strength and specificity of native promoter can be tailored by manipulating its 'cis-architecture' by the use of several recombinant DNA technologies. Newly derived chimeric promoters with specific attributes are emerging as an efficient tool for plant molecular biology. In the last three decades, synthetic promoters have been used to regulate plant gene expression. To better understand synthetic promoters, in this article, we reviewed promoter structure, the scope of cis-engineering, strategies for their development, their importance in plant biology and the total number of such promoters (188) developed in planta to date; we then categorized them under different functional regimes as biotic stress-inducible, abiotic stress-inducible, light-responsive, chemical-inducible, hormone-inducible, constitutive and tissue-specific. Furthermore, we identified a set of 36 synthetic promoters that control multiple types of expression in planta. Additionally, we illustrated the differences between native and synthetic promoters and among different synthetic promoter in each group, especially in terms of efficiency and induction conditions. As a prospective of this review, the use of ideal synthetic promoters is one of the prime requirements for generating transgenic plants suitable for promoting sustainable agriculture and plant molecular farming.

No abstract

Specific antibodies prepared against cutinase from Fusarium solani pisi and diisopropylfluorophosphate, a potent inhibitor of this enzyme, prevented infection of the host (pea epicotyl) by this organism, without affecting the viability of the spores. This finding shows that enzymatic penetration of cuticle is involved in pathogenesis.

BackgroundDesigning functionally efficient recombinant promoters having reduced sequence homology and enhanced promoter activity will be an important step toward successful stacking or pyramiding of genes in a plant cell for developing transgenic plants expressing desired traits(s). Also basic knowledge regarding plant cell specific expression of a transgene under control of a promoter is crucial to assess the promoter's efficacy.Methodology/Principal FindingsWe have constructed a set of 10 recombinant promoters incorporating different up-stream activation sequences (UAS) of Mirabilis mosaic virus sub-genomic transcript (MS8, -306 to +27) and TATA containing core domains of Figwort mosaic virus sub-genomic transcript promoter (FS3, −271 to +31). Efficacies of recombinant promoters coupled to GUS and GFP reporter genes were tested in tobacco protoplasts. Among these, a 369-bp long hybrid sub-genomic transcript promoter (MSgt-FSgt) showed the highest activity in both transient and transgenic systems. In a transient system, MSgt-FSgt was 10.31, 2.86 and 2.18 times more active compared to the CaMV35S, MS8 and FS3 promoters, respectively. In transgenic tobacco (Nicotiana tabaccum, var. Samsun NN) and Arabidopsis plants, the MSgt-FSgt hybrid promoter showed 14.22 and 7.16 times stronger activity compared to CaMV35S promoter respectively. The correlation between GUS activity and uidA-mRNA levels in transgenic tobacco plants were identified by qRT-PCR. Both CaMV35S and MSgt-FSgt promoters caused gene silencing but the degree of silencing are less in the case of the MSgt-FSgt promoter compared to CaMV35S. Quantification of GUS activity in individual plant cells driven by the MSgt-FSgt and the CaMV35S promoter were estimated using confocal laser scanning microscopy and compared.Conclusion and SignificanceWe propose strong recombinant promoter MSgt-FSgt, developed in this study, could be very useful for high-level constitutive expression of transgenes in a wide variety of plant cells.

A full-length transcript (FLt) promoter fragment was isolated from a genomic clone of mirabilis mosaic virus (MMV), a double-stranded DNA plant pararetrovirus belonging to the caulimovirus family. The boundaries required for maximal promoter expression were defined by 5' and 3' deletion analysis of the MMV promoter fragments coupled to a GUS reporter gene. The expression patterns of these chimeric gene constructs were evaluated both in transgenic Nicotiana tabacum cv. Samsun NN plants and in protoplast transient expression experiments. A 360 bp FLt promoter fragment (sequence -297 to +63 from the transcription start site) was found sufficient for strong promoter activity. The transcription start site (TSS) of the MMV FLt promoter was determined by primer extension analysis using total RNA isolated from transgenic plants containing a MMV promoter:uidA fusion gene. Analysis of the 5' and 3' deletion constructs showed that an upstream region (sequence -248 to -193 from the transcription start site) is required for the MMV FLt promoter activity along with the as-1, TATA box regions. In addition, a 31 bp sequence (+33 to +63 from the transcription start site) located downstream of a TATA box is also essential for the maximum expression of the MMV FLt promoter. Analysis of transcripts (mRNA) from these chimeric constructs also indicated that the MMV FLt promoter fragment (-297 to +63 from the transcription start site) has the highest promoter activity. In a comparative analysis the MMV FLt promoter showed much greater activity than the CaMV 35S promoter.

Magainins are a group of short peptides originally isolated from frog skin and thought to function as a natural defense mechanism against infection due to their antimicrobial properties. The engineered magainin analog peptide Myp30 was found to inhibit spore germination of the oomycete, Peronospora tabacina (Adam) in vitro, and the growth of a bacterial pathogen Erwinia carotovora subsp. carotovora (Jones). Transgenic tobacco (Nicotiana tabacum L.) plants expressing Myp30 were evaluated for resistance to these pathogens. The expression of the peptide only to an extracellular location resulted in significant reduction in sporulation and lesion size due to P. tabacina infection. A significant increase in resistance to the bacterial pathogen was also observed regardless of the targeting location of the peptide.