Claude Fauquet - Academia.edu (original) (raw)

Papers by Claude Fauquet

Physiological and Molecular Plant Pathology, 2001

Rice yellow mottle virus (RYMV) accumulation in protoplasts and whole plants was investigated in ... more Rice yellow mottle virus (RYMV) accumulation in protoplasts and whole plants was investigated in two highly resistant cultivars, Tog5681 (Oryza glaberrima) and Gigante (Oryza sativa). Three susceptible cultivars, i.e. one O. glaberrima Tog5673 and two O. sativa (IR64, Ac. 2428), and a partially resistant cultivar (Azucena) were used as control. After inoculation, accumulation of coat protein (CP) and viral RNA were monitored on protoplasts, inoculated leaves, sheaths of inoculated leaves and newly infected leaves by serological and Northern blot analysis. Viral RNA accumulated to a similar extent in protoplasts from all cultivars studied. In contrast, three distinct in planta behaviors were noted. In susceptible plants (IR64, Tog5673 and Ac. 2428), there was high CP and RNA accumulation at 5 d.p.i. in whole plants, suggesting that cell to cell and vascular movements occurred before 5 d.p.i. in inoculated leaves. The second behavior concerned Azucena, which showed a delay (around 7 d.p.i.) of viral accumulation in inoculated leaves. The third behavior involved the highly resistant cultivars Tog5681 and Gigante. CP and viral RNA were not detected in these cultivars. The comparison of viral accumulation in protoplasts and plants suggested that resistance of the highly resistant cultivars Tog5681 (O. glaberrima) and Gigante (O. sativa) was not due to the inhibition of virus replication but rather to the failure of cell to cell movement.

Nature biotechnology, 1998

The ability to control integration, inheritance, and expression of multiple transgenes is a prere... more The ability to control integration, inheritance, and expression of multiple transgenes is a prerequisite for manipulating biosynthetic pathways and complex agronomic characteristics in plants. One hundred and twenty-five independent transgenic rice plants were regenerated after cobombarding embryogenic tissues with a mixture of 14 different pUC-based plasmids. Eighty-five percent of the R0 plants contained more than two, and 17% more than nine, of the target genes. Plants containing multiple transgenes displayed normal morphologies and 63% set viable seed. Multigene cotransformation efficiency was correlated with the ratio in which the plasmids were mixed with respect to the selectable marker. All target genes had an equal chance of integration, indicating that the nature of the coding region had no effect on the efficiency of integration. Three plant lines containing 11, 10, and 9 transgenes, respectively, were analyzed for patterns of integration and inheritance until the R3 gener...

Plant Science, 1998

The histology and time course of hygromycin-resistant callus formation from bombarded, seed embry... more The histology and time course of hygromycin-resistant callus formation from bombarded, seed embryo scutellumderived embryogenic nodular units (ENUs) were investigated in four japonica rice cultivars (Taipei309, IDSA6, IR47686, IRAT361) exhibiting contrasting amenabilies in a microprojectile-mediated transformation system. ENUs from the above genotypes collected at a stage considered suitable for bombardment, exhibited contrasted organization in their peripheral regions. This organization was found to influence the hygromycin concentration requested to stop ENU growth, along with the amenability of transformed cells to evolve into isolated, clonal, transgenic resistant calli, from the rest of the ENU. Organized globular proembryos located at the periphery of ENUs proved to be quite tolerant to antibiotic selection. They also developed in selective induction medium, irrespective of whether they had been sectorially transformed or not, and produced chimaeric or clonal, non-transgenic proliferations. In contrast, the presence of a single layer or small clusters of embryogenic cells at the periphery of the bombarded ENU, whose growth was fully inhibited under a selective regime, generally led to the formation of clonal transgenic calli. An average of 2.5, 4.3, and 3.2 hygromycin resistant calli were produced per responding ENU in Taipei 309, IDSA6 and IR47686, respectively. We obtained histological and molecular evidence that the hygromycin resistant calli arising from a single bombarded ENU may have been formed through independent transformation events.

Phytopathology, 1999

1999. Near immunity to rice tungro spherical virus achieved in rice by a replicase-mediated resis... more 1999. Near immunity to rice tungro spherical virus achieved in rice by a replicase-mediated resistance strategy. Phytopathology 89:1022-1027.

We compared rice transgenic plants obtained by Agrobacterium-mediated and particle bombardment tr... more We compared rice transgenic plants obtained by Agrobacterium-mediated and particle bombardment transfor- mation by carrying out molecular analyses of the T0 ,T 1 and T2 transgenic plants. Oryza sativa japonica rice (c.v. Taipei 309) was transformed with a construct (pWNHG) that carried genes coding for neomycin phospho- transferase (nptII), hygromycin phosphotransferase (Hygr), and -glucuronidase (GUS). Thirteen and fourteen transgenic lines

Annual Review of Plant Biology, 2011

More than 250 million Africans rely on the starchy root crop cassava (Manihot esculenta) as their... more More than 250 million Africans rely on the starchy root crop cassava (Manihot esculenta) as their staple source of calories. A typical cassavabased diet, however, provides less than 30% of the minimum daily requirement for protein and only 10%-20% of that for iron, zinc, and vitamin A. The BioCassava Plus (BC+) program has employed modern biotechnologies intended to improve the health of Africans through the development and delivery of genetically engineered cassava with increased nutrient (zinc, iron, protein, and vitamin A) levels. Additional traits addressed by BioCassava Plus include increased shelf life, reductions in toxic cyanogenic glycosides to safe levels, and resistance to viral disease. The program also provides incentives for the adoption of biofortified cassava. Proof of concept was achieved for each of the target traits. Results from field trials in Puerto Rico, the first confined field trials in Nigeria to use genetically engineered organisms, and ex ante impact analyses support the efficacy of using transgenic strategies for the biofortification of cassava.

Food Security, 2014

The importance of cassava as a food security crop in Africa and the world Cassava, originally fro... more The importance of cassava as a food security crop in Africa and the world Cassava, originally from South America, is the fourth most important source of calories in the developing world after the cereal crops wheat, maize, and rice. Worldwide, it feeds an estimated 700 million people directly or indirectly. Cassava production has increased steadily for the last 50 years, with 242 MT harvested in 2012. The increase is likely to continue as farmers in more than 105 countries come to recognize the crop's advantages. A semi-perennial root crop, cassava can stay in the ground for up to 3 years. This makes it an excellent food security crop: when all other crops have been exhausted, cassava roots can still be harvested. It is naturally drought resistant and resilient to climatic changes, high temperatures, and poor soils, and in addition, cassava responds extremely well to high CO 2 concentrations, making it a very important crop for the 21st century. Africa alone accounts for more than 55 % of the world's production, and cassava is the first food crop in fresh tonnage before maize and plantain in sub-Saharan Africa. Cassava is also an important source of income, especially for women in sub-Saharan Africa (SSA). Furthermore, cassava is the second most important source of starch in the world. Cassava is thus a highly valuable crop for the world today and in the future. It is critical that it should not be compromised by viral diseases.

Virology, 1998

Rice yellow mottle sobemovirus (RYMV) is responsible for the yellow mottle disease on rice in Afr... more Rice yellow mottle sobemovirus (RYMV) is responsible for the yellow mottle disease on rice in Africa. The expression and function of the protein P1 (17.8 kDa) encoded by the first open reading frame (ORF) of RYMV was investigated. Using an antibody raised against purified P1, two proteins with apparent molecular masses of 18 and 19 kDa were identified in in vitro translation reactions of transcripts of the full-length cDNA of RYMV. Likewise, gene products with similar molecular mass were detected in inoculated and systemically infected rice leaves and in infected rice protoplasts. A mutant from which ORF1 nucleotides 88 to 547 were deleted and a frameshift mutant that resulted in truncation of 83 amino acids from the C terminus of P1 were incapable of replicating in protoplasts. In contrast, a mutant that does not express P1 due to a mutation at the initiation codon replicated efficiently in protoplasts but at a reduced level (about 0.5-to 2-fold less) compared to replication of wild-type RNA. None of these mutants caused systemic infection in rice plants. Transgenic rice plants that express P1 complemented the initiation codon mutant, but not the deletion mutants, and produced systemic infection. These experiments demonstrate that P1 of RYMV is dispensible for virus replication, although nucleotide deletions or additions in ORF1 are apparently lethal for virus replication. Furthermore, P1 of RYMV is required for the infection of plants and is important for virus spread.

Virology, 2002

Rice yellow mottle virus (RYMV) is icosahedral in morphology and known to swell in vitro, but the... more Rice yellow mottle virus (RYMV) is icosahedral in morphology and known to swell in vitro, but the biological function of swollen particles remains unknown. Anion-exchange chromatography was used to identify three markedly stable forms of RYMV particles from infected plants: (1) an unstable swollen form lacking Ca 2ϩ and dependent upon basic pH; (2) a more stable transitional form lacking Ca 2ϩ but dependent upon acidic pH; and (3) a pH-independent, stable, compact form containing Ca 2ϩ . Particle stability increased over the time course of infection in rice plants: transitional and swollen forms were abundant during early infection (2 weeks postinfection), whereas compact forms increased during later stages of infection. Electron microscopy of infected tissue revealed virus particles in vacuoles of xylem parenchyma and mesophyll cells early in the time course of infection and suggested that vacuoles and other vesicles were the major storage compartments for virus particles. We propose a model in which virus maturation is associated with the virus accumulation in vacuoles. In this acidic compartment, virus particles may bind Ca 2ϩ to produce a highly stable, compact form of the virus. The localization of subcellular RYMV isoforms in infected cells and the corresponding biological properties of the virus are discussed. © 2002 Elsevier Science (USA)

Virology, 1995

A full-length cDNA clone of rice yellow mottle sobemovirus (RYMV) was synthesized and placed adja... more A full-length cDNA clone of rice yellow mottle sobemovirus (RYMV) was synthesized and placed adjacent to a bacteriophage T7 RNA polymerase promoter sequence. Capped-RNA transcripts produced in vitro were infectious when mechanically inoculated onto rice plants (Oryza sativa L.). Individual full-length clones varied in their degree of infectivity but all were less infectious than native viral RNA. A representative clone, designated RYMV-FL5, caused a disease phenotype identical to that produced by viral RNA except that symptoms were somewhat slower to appear than those induced by viral RNA. The infectivity of RYMV-FL5 was verified by ELISA, Western blot analysis, Northern blot hybridization, RT-PCR, and Southern blot hybridization. Frameshift and deletion mutations introduced into the coat protein cistron demonstrated that the coat protein was dispensable for RNA replication in rice protoplasts. However, the coat protein was required for full infectivity in rice plants, presumably by playing a role in phloem-mediated long-distance movement and possibly in cell-to-cell movemeat.

Virology, 1999

Rice tungro bacilliform virus (RTBV) is a plant pararetrovirus and a member of the Caulimoviridae... more Rice tungro bacilliform virus (RTBV) is a plant pararetrovirus and a member of the Caulimoviridae family and closely related to viruses in the Badnavirus genus. The coat protein of RTBV is part of the large polyprotein encoded by open reading frame 3 (ORF3). ORF3 of an RTBV isolate from Malaysia was sequenced (accession no. AF076470) and compared with published sequences for the region that encodes the coat protein or proteins. Molecular mass of virion proteins was determined by mass spectrometry (matrix-assisted laser desorption/ionization-TOF) performed on purified virus particles from three RTBV isolates from Malaysia. The Nand C-terminal amino acid sequences of the coat protein were deduced from the mass spectral analysis, leading to the conclusion that purified virions contain a single coat protein of 37 kDa. The location of the coat protein domain in ORF3 was reinforced as a result of immunodetection reactions using antibodies raised against six different segments of ORF3 using Western immunoblots after SDS-PAGE and isoelectrofocusing of proteins purified from RTBV particles. These studies demonstrate that RTBV coat protein is released from the polyprotein as a single coat protein Of 37 kDa. O i999 Academic Press

PROTEOMICS, 2006

Using high-resolution 2-DE, we resolved proteins extracted from fibrous and tuberous root tissues... more Using high-resolution 2-DE, we resolved proteins extracted from fibrous and tuberous root tissues of 3-month-old cassava plants. Gel image analysis revealed an average of 1467 electrophoretically resolved spots on the fibrous gels and 1595 spots on the tuberous gels in pH 3-10 range. Protein spots from both sets of gels were digested with trypsin. The digests were subjected to nanoelectrospray quadrupole TOF tandem mass analysis. Currently, we have obtained 299 protein identifications for 292 gel spots corresponding to 237 proteins. The proteins span various functional categories from energy, primary and secondary metabolism, disease and defense, destination and storage, transport, signal transduction, protein synthesis, cell structure, and transcription to cell growth and division. Gel image analysis has shown unique, as well as upand down-regulated proteins, present in the tuberous and the fibrous tissues. Quantitative and qualitative analysis of the cassava root proteome is an important step towards further characterization of differentially expressed proteins and the elucidation of the mechanisms underlying the development and biological functions of the two types of roots.

Proceedings of the National Academy of Sciences, 1998

Oryza sativa L. leaves was characterized by Western immunoblotting, Northern blotting, and electr... more Oryza sativa L. leaves was characterized by Western immunoblotting, Northern blotting, and electron microscopy of thin sections. In inoculated leaves, RYMV RNA and coat protein first were detected at 3 and 5 days postinoculation, respectively. By 6 days postinoculation, RYMV had spread systemically to leaves, and virus particles were observed in most cell types, including epidermal, mesophyll, bundle sheath, and vascular parenchyma cells.

Plant Molecular Biology, 1991

The bacterial gene encoding beta-glucuronidase (GUS) was transiently expressed in cassava leaves ... more The bacterial gene encoding beta-glucuronidase (GUS) was transiently expressed in cassava leaves following the introduction of the gene by microparticle bombardment. The DNA expression vector used to introduce the reporter gene is a pUC 19 derivative and consisted of a CaMV 35S promoter (P35S), the GUS coding region and 7S polyadenylation region. Several other promoters and regulating sequences were tested for efficiency in cassava leaves. Two derivatives of the P35S, one including a partial duplication of the upstream region of the P35S and the other containing a tetramer of the octopine synthase enhancer, were found to be expressed at three times the level of the P35S in cassava leaves. The ubiquitin 1 promoter from Arabidopsis thaliana was expressed at the same level as the P35S. No influence on the level of expression was observed when different 3' ends were used. The biolistic transient gene expression system in cassava leaves allows rapid analysis of gene constructs and can serve as a preliminary screen for chimeric gene function in the construction of transgenic cassava plants.

Plant Disease, 2005

... discussed. Impact of RYMV on Rice Production Disease incidence. RYMV was first re-ported in 1... more ... discussed. Impact of RYMV on Rice Production Disease incidence. RYMV was first re-ported in 1970 in the Nyanza province of western Kenya near Lake Victoria (13). Subsequently ... observed. Ac-cording to Ioannidou et al. (32 ...

Plant Cell Reports, 1994

Regeneration of indica rice varieties remains a limiting factor for researchers undertaking rice ... more Regeneration of indica rice varieties remains a limiting factor for researchers undertaking rice transformation experiments. As reported for japonica rice and other crops, partial desiccation of indica rice calli dramatically promotes organogenesis and leads to high regeneration ability. We are now able to obtain 66.5%, 61.1% and 73.7% of calli that regenerate plants for the indica varieties TN1, IR72 and IR64 whereas in non desiccated controls only 30.0%, 15.5% and 18.7% of calli regenerated, respectively. Plants obtained were phenotypically normal and 50% were highly fertile. Partial desiccation is a reliable and simple method for improving indica rice regeneration. It also shortens the

Plant Cell Reports, 1996

The microprojectile bombardment of immature embryos has proven to be effective in transforming ma... more The microprojectile bombardment of immature embryos has proven to be effective in transforming many itzdica rice varieties. One of the drawbacks of using immature embryos is the requirement of a large number of high quality immature embryos, which itself is a tedious and laborious process. To circumvent these problems, we have developed a procedure, using indica variety TN1 as a model that generates highly homogenous populations of embryogenic subcultured calli by selectively propagating a small number of regeneration-proficient calli derived from seeds. Thousands of embryogenic calli were produced from 50 seeds within 10 weeks. Ten to 20 independent RO transgenic lines were regenerated per 500 embryogenic calli bombarded. The convenience and reliability offered by this transformation system has made transformation of irzdica rice a routine procedure.