Genetic transformation of Vitis vinifera via organogenesis

Background  

Efficient transformation and regeneration methods are a priority for successful application of genetic engineering to vegetative propagated plants such as grape. The current methods for the production of transgenic grape plants are based on Agrobacterium-mediated transformation followed by regeneration from embryogenic callus. However, grape embryogenic calli are laborious to establish and the phenotype of the regenerated plants can be altered.     

Genome scale transcriptome analysis of shoot organogenesis in Populus

Background  

Our aim is to improve knowledge of gene regulatory circuits important to dedifferentiation, redifferentiation, and adventitious meristem organization during in vitro regeneration of plants. Regeneration of transgenic cells remains a major obstacle to research and commercial deployment of most taxa of transgenic plants, and woody species are particularly recalcitrant. The model woody species Populus, due to its genome sequence and amenability to in vitro manipulation, is an excellent species for study in this area. The genes recognized may help to guide the development of new tools for improving the efficiency of plant regeneration and transformation.     

A systemic gene silencing method suitable for high throughput,reverse genetic analyses of gene function in fern gametophytes

Background  

Ceratopteris richardii is a useful experimental system for studying gametophyte development and sexual reproduction in plants. However, few tools for cloning mutant genes or disrupting gene function exist for this species. The feasibility of systemic gene silencing as a reverse genetics tool was examined in this study.     

Analysis of a post-translational steroid induction system for GIGANTEA in Arabidopsis

Background  

To investigate the link between the flowering time gene GIGANTEA (GI) and downstream genes, an inducible GI system was developed in Arabidopsis thaliana L. Heynh. Transgenic Arabidopsis plant lines were generated with a steroid-inducible post-translational control system for GI. The gene expression construct consisted of the coding region of the GI protein fused to that of the ligand binding domain of the rat glucocorticoid receptor (GR). This fusion gene was expressed from the constitutive cauliflower mosaic virus 35S promoter and was introduced into plants carrying the gi-2 mutation. Application of the steroid dexamethasone (DEX) was expected to result in activation of the GI-GR protein and its relocation from the cytoplasm to the nucleus.     

High-level HIV-1 Nef transient expression in Nicotiana benthamiana using the P19 gene silencing suppressor protein of Artichoke Mottled Crinckle Virus

Background  

In recent years, different HIV antigens have been successfully expressed in plants by either stable transformation or transient expression systems. Among HIV proteins, Nef is considered a promising target for the formulation of a multi-component vaccine due to its implication in the first steps of viral infection. Attempts to express Nef as a single protein product (not fused to a stabilizing protein) in transgenic plants resulted in disappointingly low yields (about 0.5% of total soluble protein). In this work we describe a transient expression system based on co-agroinfiltration of plant virus gene silencing suppressor proteins in Nicotiana benthamiana, followed by a two-step affinity purification protocol of plant-derived Nef.     

Doxycycline-regulated gene expression in the opportunistic fungal pathogen Aspergillus fumigatus

Background  

Although Aspergillus fumigatus is an important human fungal pathogen there are few expression systems available to study the contribution of specific genes to the growth and virulence of this opportunistic mould. Regulatable promoter systems based upon prokaryotic regulatory elements in the E. coli tetracycline-resistance operon have been successfully used to manipulate gene expression in several organisms, including mice, flies, plants, and yeast. However, the system has not yet been adapted for Aspergillus spp.     

Stable expression and phenotypic impact of <Emphasis Type="Italic">attacin E</Emphasis>transgene in orchard grown apple trees over a 12 year period

Background  

Transgenic trees currently are being produced by Agrobacterium -mediated transformation and biolistics. The future use of transformed trees on a commercial basis depends upon thorough evaluation of the potential environmental and public health risk of the modified plants, transgene stability over a prolonged period of time and the effect of the gene on tree and fruit characteristics. We studied the stability of expression and the effect on resistance to the fire blight disease of the lytic protein gene, attacin E, in the apple cultivar 'Galaxy' grown in the field for 12 years.     

Effect of oxygen availability on nitrogen fixation by two Lotus species under flooded conditions

The pasture legumes Lotus uliginosus (Schk.) and Lotus corniculatus (L.), known to differ in their tolerance to flooding, were inoculated with Rhizobium loti and flooded for 60 d while subjected to two levels of dissolved pO2: 0.241 and 0.094 mol ml^-1. L. uliginosus showed significantly greater growth (shoot and root) and N2 fixation under both pO2s, compared to L. corniculatus, although growth and N2 fixation by L. corniculatus was not affected by the low pO2. Surprisingly, in L. uliginosus., growth, nodulation and N2 fixation were all increased by low pO2 while nodulation of L. corniculatus where low pO2 plants showed a significant increase over that of the higher pO2 plants while L. uliginosus plants showed a decline. Root porosity of L. uliginosus doubled in the low pO2-treatment from a mean of 14.5% in high pO2 roots to 28.5%, whereas that of L. corniculatus was relatively unaffected by pO2, being 7% and 9% for high and low pO2 plants, respectively. The structure of nodules differed little between species and treatments, although nodules/nodulated roots from the L. uliginosus plants had particularly profuse lenticels and aerenchyma. However, L. corniculatus nodules, especially those grown in the lower pO2 showed signs of early senescence with vacuolation of infected cells and green coloration when cut open. Leghaemoglobin (Lb) concentrations in nodules from both species were unaffected by low pO2, although that of L. corniculatus nodules, regardless of pO2, was significantly greater than L. uliginosus. Concentrations of the intercellular glycoprotein recognized by the monoclonal antibody MAC265 were significantly reduced in nodules from the low pO2 treatment in both species. Immunogold labelling showed that the MAC265 antigen was localized primarily within intercellular spaces within nodule cortices from both Lotus species. A marked decrease in deposition of the MAC265 antigen within the cortices of L. uliginosus nodules grown in the lower pO2, is discussed in terms of the relative abilities of the two Lotus spp. to maintain an O2 supply to the N2-fixing bacteroids within submerged nodules.Keywords: Lotus uliginosus, Lotus corniculatus, N2 fixation, flooding, oxygen.      

Evolution of Parallel Spindles Like genes in plants and highlight of unique domain architecture#

Background  

Polyploidy has long been recognized as playing an important role in plant evolution. In flowering plants, the major route of polyploidization is suggested to be sexual through gametes with somatic chromosome number (2n). Parallel Spindle1 gene in Arabidopsis thaliana (AtPS1) was recently demonstrated to control spindle orientation in the 2nd division of meiosis and, when mutated, to induce 2n pollen. Interestingly, AtPS1 encodes a protein with a FHA domain and PINc domain putatively involved in RNA decay (i.e. Nonsense Mediated mRNA Decay). In potato, 2n pollen depending on parallel spindles was described long time ago but the responsible gene has never been isolated. The knowledge derived from AtPS1 as well as the availability of genome sequences makes it possible to isolate potato PSLike (PSL) and to highlight the evolution of PSL family in plants.     

Characterisation of the legume SERK-NIK gene superfamily including splice variants: Implications for development and defence

Background  

SOMATIC EMBRYOGENESIS RECEPTOR-LIKE KINASE (SERK) genes are part of the regulation of diverse signalling events in plants. Current evidence shows SERK proteins function both in developmental and defence signalling pathways, which occur in response to both peptide and steroid ligands. SERKs are generally present as small gene families in plants, with five SERK genes in Arabidopsis. Knowledge gained primarily through work on Arabidopsis SERKs indicates that these proteins probably interact with a wide range of other receptor kinases and form a fundamental part of many essential signalling pathways. The SERK1 gene of the model legume, Medicago truncatula functions in somatic and zygotic embryogenesis, and during many phases of plant development, including nodule and lateral root formation. However, other SERK genes in M. truncatula and other legumes are largely unidentified and their functions unknown.     

The cinnamyl alcohol dehydrogenase gene family in Populus: phylogeny, organization, and expression

Background  

Lignin is a phenolic heteropolymer in secondary cell walls that plays a major role in the development of plants and their defense against pathogens. The biosynthesis of monolignols, which represent the main component of lignin involves many enzymes. The cinnamyl alcohol dehydrogenase (CAD) is a key enzyme in lignin biosynthesis as it catalyzes the final step in the synthesis of monolignols. The CAD gene family has been studied in Arabidopsis thaliana, Oryza sativa and partially in Populus. This is the first comprehensive study on the CAD gene family in woody plants including genome organization, gene structure, phylogeny across land plant lineages, and expression profiling in Populus.     

Evolution of plant RNA polymerase IV/V genes: evidence of subneofunctionalization of duplicated <Emphasis Type="Italic">NRPD2/NRPE2</Emphasis>-like paralogs in <Emphasis Type="Italic">Viola</Emphasis> (Violaceae)

Background  

DNA-dependent RNA polymerase IV and V (Pol IV and V) are multi-subunit enzymes occurring in plants. The origin of Pol V, specific to angiosperms, from Pol IV, which is present in all land plants, is linked to the duplication of the gene encoding the largest subunit and the subsequent subneofunctionalization of the two paralogs (NRPD1 and NRPE1). Additional duplication of the second-largest subunit, NRPD2/NRPE2, has happened independently in at least some eudicot lineages, but its paralogs are often subject to concerted evolution and gene death and little is known about their evolution nor their affinity with Pol IV and Pol V.     

Integration of molecular biology tools for identifying promoters and genes abundantly expressed in flowers of Oncidium Gower Ramsey

Background  

Orchids comprise one of the largest families of flowering plants and generate commercially important flowers. However, model plants, such as Arabidopsis thaliana do not contain all plant genes, and agronomic and horticulturally important genera and species must be individually studied.     

Characterization and isolation of a T-DNA tagged banana promoter active during in vitro culture and low temperature stress

Background  

Next-generation transgenic plants will require a more precise regulation of transgene expression, preferably under the control of native promoters. A genome-wide T-DNA tagging strategy was therefore performed for the identification and characterization of novel banana promoters. Embryogenic cell suspensions of a plantain-type banana were transformed with a promoterless, codon-optimized luciferase (luc ⁺) gene and low temperature-responsive luciferase activation was monitored in real time.     

Evolutionary genomics of LysM genes in land plants

Background  

The ubiquitous LysM motif recognizes peptidoglycan, chitooligosaccharides (chitin) and, presumably, other structurally-related oligosaccharides. LysM-containing proteins were first shown to be involved in bacterial cell wall degradation and, more recently, were implicated in perceiving chitin (one of the established pathogen-associated molecular patterns) and lipo-chitin (nodulation factors) in flowering plants. However, the majority of LysM genes in plants remain functionally uncharacterized and the evolutionary history of complex LysM genes remains elusive.     

Identification and targeted disruption of the mouse gene encoding ESG1 (PH34/ECAT2/DPPA5)

Background  

Embryonic stem cell-specific gene (ESG) 1, which encodes a KH-domain containing protein, is specifically expressed in early embryos, germ cells, and embryonic stem (ES) cells. Previous studies identified genomic clones containing the mouse ESG1 gene and five pseudogenes. However, their chromosomal localizations or physiological functions have not been determined.     

Quantitative promoter analysis in <Emphasis Type="Italic">Physcomitrella patens</Emphasis>: a set of plant vectors activating gene expression within three orders of magnitude

Background  

In addition to studies of plant gene function and developmental analyses, plant biotechnological use is largely dependent upon transgenic technologies. The moss Physcomitrella patens has become an exciting model system for studying plant molecular processes due to an exceptionally high rate of nuclear gene targeting by homologous recombination compared with other plants. However, its use in transgenic approaches requires expression vectors that incorporate sufficiently strong promoters. To satisfy this requirement, a set of plant expression vectors was constructed and equipped with either heterologous or endogenous promoters.