Methods and compositions for regulating gene expression in plant cells

Novel chimeric plant promoter sequences are provided, together with plant gene expression cassettes comprising such sequences. In certain preferred embodiments, the chimeric plant promoters comprise the BoxII cis element and/or derivatives thereof. In addition, novel transcription factors are provided, together with nucleic acid sequences encoding such transcription factors and plant gene expression cassettes comprising such nucleic acid sequences. In certain preferred embodiments, the novel transcription factors comprise the acidic domain, or fragments thereof, of the RF2a transcription factor. Methods for using the chimeric plant promoter sequences and novel transcription factors in regulating the expression of at least one gene of interest are provided, together with transgenic plants comprising such chimeric plant promoter sequences and novel transcription factors

Studies of Coat Protein-Mediated Resistance to TMV I. The PM2 Assembly Defective Mutant Confers Resistance to TMV

AbstractTobacco mosaic virus mutant PM2 contains two amino acid changes in coat protein sequence relative to the sequence of the coat protein of TMV U1. This results in unstable infectivity, inability to cause normal systemic infection, and accumulation of elongated open helixes of coat protein. Using site-directed mutagenesis we demonstrated that the characteristics of PM2 are due to the change of Thr28 → Ile, while the second change, Glu95 → Asp, had no apparent effect on virion structure or infectivity. Transgenic Nicotiana tabacum cv Xanthi NN and Xanthi nn plants that accumulate coat protein that contains one or both of the amino acid changes are as resistant to TMV infection as transgenic plants that contain wildtype TMV coat protein. The implication of these results on a model for coat protein-mediated resistance that involves the interaction of transgenic coat protein with the challenge virus is discussed

Functional analysis of RF2a, a rice transcription factor

RF2a is a bZIP transcription factor that regulates expression of the promoter of rice tungro bacilliform bad-navirus. RF2a is predicted to include three domains that contribute to its function. The results of transient assays with mutants of RF2a from which one or more domains were removed demonstrated that the acidic domain was essential for the activation of gene expression, although the proline-rich and glutamine-rich domains each played a role in this function. Studies using fusion proteins of different functional domains of RF2a with the 2C7 synthetic zinc finger DNA-binding domain showed that the acidic region is a relatively strong activation domain, the function of which is dependent on the context in which the domain is placed. Data from transgenic plants further supported the conclusion that the acidic domain was important for maintaining the biological function of RF2a. RF2a and TBP (TATA-binding protein) synergistically activate transcription in vitro (Zhu, Q., Ordiz, M. I., Dabi, T., Beachy, R. N., and Lamb, C. (2002) Plant Cell 14, 795-803). In vitro and in vivo assays showed that RF2a interacts with TBP through the glutamine-rich domain but not the acidic domain. Functional analysis of such interactions indicates that the acidic domain activates transcription through mechanisms other than via the direct recruitment of TBP.Fil: Dai, Shunhong. Chinese Academy of Sciences; República de China. Donald Danforth Plant Science Center; Estados UnidosFil: Petruccelli, Silvana. Donald Danforth Plant Science Center; Estados Unidos. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; ArgentinaFil: Ordiz, Maria Isabel. Donald Danforth Plant Science Center; Estados UnidosFil: Zhang, Zhihong. Donald Danforth Plant Science Center; Estados UnidosFil: Chen, Shouyi. Chinese Academy of Sciences; República de ChinaFil: Beachy, Roger N.. Donald Danforth Plant Science Center; Estados Unido

Characterization of the protease domain of Rice tungro bacilliform virus responsible for the processing of the capsid protein from the polyprotein

BACKGROUND: Rice tungro bacilliform virus (RTBV) is a pararetrovirus, and a member of the family Caulimoviridae in the genus Badnavirus. RTBV has a long open reading frame that encodes a large polyprotein (P3). Pararetroviruses show similarities with retroviruses in molecular organization and replication. P3 contains a putative movement protein (MP), the capsid protein (CP), the aspartate protease (PR) and the reverse transcriptase (RT) with a ribonuclease H activity. PR is a member of the cluster of retroviral proteases and serves to proteolytically process P3. Previous work established the N- and C-terminal amino acid sequences of CP and RT, processing of RT by PR, and estimated the molecular mass of PR by western blot assays. RESULTS: A molecular mass of a protein that was associated with virions was determined by in-line HPLC electrospray ionization mass spectral analysis. Comparison with retroviral proteases amino acid sequences allowed the characterization of a putative protease domain in this protein. Structural modelling revealed strong resemblance with retroviral proteases, with overall folds surrounding the active site being well conserved. Expression in E. coli of putative domain was affected by the presence or absence of the active site in the construct. Analysis of processing of CP by PR, using pulse chase labelling experiments, demonstrated that the 37 kDa capsid protein was dependent on the presence of the protease in the constructs. CONCLUSION: The findings suggest the characterization of the RTBV protease domain. Sequence analysis, structural modelling, in vitro expression studies are evidence to consider the putative domain as being the protease domain. Analysis of expression of different peptides corresponding to various domains of P3 suggests a processing of CP by PR. This work clarifies the organization of the RTBV polyprotein, and its processing by the RTBV protease

Green, Adam. Selling the Race: Culture, Community and Black Chicago, 1940–1955. Chicago: University of Chicago Press, 2007. 280 pp.

Agreement is developing among agricultural scientists on the emerging inability of agriculture to meet growing global food demands. Changes in trends of weather conditions projected by global climate models will challenge physiological limits of crops and exacerbate the global food challenge by 2050. These climate- and constraint-driven crop production challenges are interconnected within a complex global economy, where diverse factors add to price volatility and food scarcity. Our scenarios of the impact of climate change on food security through 2050 for internationally traded crops show that climate change does not threaten near-term US food security due to the availability of adaptation strategies. However, as climate continues to change beyond 2050 current adaptation measures will not be sufficient to meet growing food demand. Climate scenarios for higher-level carbon emissions exacerbate the food shortfall, although uncertainty in projections of future precipitation is a limitation to impact studies

Transcription factor RF2a alters expression of the rice tungro bacilliform virus promoter in transgenic tobacco plants

The promoter from rice tungro bacilliform badnavirus (RTBV) is expressed only in phloem tissues in transgenic rice plants. RF2a, a b-Zip protein from rice, is known to bind to the Box II cis element near the TATA box of the promoter. Here, we report that the full-length RTBV promoter and a truncated fragment E of the promoter, comprising nucleotides -164 to +45, result in phloem-specific expression of β-glucuronidase (GUS) reporter genes in transgenic tobacco plants. When a fusion gene comprising the cauliflower mosaic virus 35S promoter and RF2a cDNA was coexpressed with the GUS reporter genes, GUS activity was increased by 2-20-fold. The increase in GUS activity was positively correlated with the amount of RF2a, and the expression pattern of the RTBV promoter was altered from phloem-specific to constitutive. Constitutive expression of RF2a did not induce morphological changes in the transgenic plants. In contrast, constitutive overexpression of the b-ZIP domain of RF2a had a strong effect on the development of transgenic plants. These studies suggest that expression of the b-Zip domain can interfere with the function of homologues of RF2a that regulate development of tobacco plants.Facultad de Ciencias ExactasCentro de Investigación y Desarrollo en Criotecnología de Alimento

Single-mode cavities at frequencies of 172 and 178 MHz

In the report presented here the projects of two accelerating cavities with strong damping of higher modes (HOM) with special vacuum loads are presented. The designs of the cavities and loads are described. The design parameters of cavities, their spectra of higher modes and calculation results of the beam phase motion stability are given for the VEPP-2000 and NANOHANA Projects