RNA editing in plant mitochondria, cytoplasmic male sterility and plant breeding

RNA editing in plant mitochondria is a post-transcriptional process involving the partial change of C residues into U. These C to U changes lead to the synthesis of proteins with an amino acid sequence different to that predicted from the gene. Proteins produced from edited mRNAs are more similar to those from organisms where this process is absent. This biochemical process involves cytidine deamination. The cytoplasmic male sterility (CMS) phenotype generated by the incompatibility between the nuclear and the mitochondrial genomes is an important agronomical trait which prevents inbreeding and favors hybrid production. The hypothesis that RNA editing leads to functional proteins has been proposed. This hypothesis was tested by constructing transgenic plants expressing a mitochondrial protein translated from unedited mRNA. The transgenic "unedited" protein was addressed to the mitochondria leading to the appearance of mitochondrial dysfunction and generating the male sterile phenotype in transgenic tobacco plants. Male sterile plants were also obtained by expressing specifically a bacterial ribonuclease in the anthers. The economical benefits of artificially engineered male-sterile plants or carrying the (native) spontaneous CMS phenotype, implies the restoration to obtain fertile hybrids that will be used in agriculture. Restoration to fertility of transgenic plants was obtained either by crossing male-sterile plants carrying the "unedited" mRNA with plants carrying the same RNA, but in the antisense orientation or, in the case of plants expresing the ribonuclease, by crossing male-sterile plants with plants expressing an inhibitor specific of this enzyme

Etude du rôle de la kinase WEE1 dans le contrôle du cycle cellulaire et de l'endoréduplication au cours de l'organogénèse du fruit de tomate (Solanum lycopersicum Mill.)

Nous avons étudié l'implication de WEE1 dans le contrôle du cycle cellulaire et de l'expansion associée à l'endoréduplication et sa contribution dans l'organogenèse et la taille du fruit, en utilisant la tomate comme modèle du développement précoce du fruit charnu. Le gène S1WEE1 a été isolé et caractérisé. S1WEE1 est exprimé dans les tissus en division et dans les tissus où se met en place le processus d'endoréduplication. L'inhibition de l'expression de S1WEE1 dans des plantes transgéniques induit une réduction de la taille des plantes et des fruits due à une diminution de la taille cellulaire qui est corrélée à une réduction du niveau de ploÏdie. S1WEE1 participe au contrôle de la taille des cellules en régulant la durée de la phase G2 du cycle cellulaire et/ou la transition vers l'endoreduplication qui conduit potentiellement à l'expansion cellulaire. Une analyse préliminaire du promoteur de S1WEE1 et de plantes surexprimant ce gène a également été réalisée.We investigated the involvement of the WEE1 gene in the control of the cell cycle and the cell expansion-associated endoreduplication and its contribution to fruit organogenesis and fruit size using Tomato as a model for fleshy fruit development. We have isolated and characterized the genomic clone containing the whole S1WEE1 gene sequence from tomato. S1WEE1 is expressed in young dividing tissues and those where endoreduplication takes place. Impairing the expression of S1WEE1 in transgenic tomato plants resulted in a reduction of plant and fruit size resulting from a reduction in cell size which could be correlated with a decrease of the DNA ploidy levels. We showed that S1WEE1 participates in the control of cell size through the length determination of the G2 phase of the cell cycle and/or the onset of the endoreduplication process putatively driving cell expansion. A preliminary study of the S1WEE1 promoter and overexpressing S1WEE1 plants has also been performed.BORDEAUX2-BU Santé (330632101) / SudocSudocFranceF

Multiplication in vitro du noisetier (Corylus avellana L.)

La micropropagation, si elle permet la mise à disposition rapide des nouveaux cultivars issus des programmes d’amélioration, deviendra un facteur important pour l’évolution du verger de noisetier. Sur matériel jeune, il a été possible d’obtenir, à partir de bourgeons axillaires, un taux de multiplication intéressant, en apportant le fer sous forme d’un chélate du commerce peu utilisé en culture in vitro ; l’enracinement et le transfert des plants sur substrat normal ne soulèvent pas de problème particulier. Malgré les résultats encourageants obtenus avec matériel adulte, des améliorations doivent encore être apportées à la technique, avant d’envisager une utilisation intensive.If new cultivars of hazel are to be distributed more rapidly than through horticultural methods, in vitro propagation will have to be considered as an important factor in future developments. From young material, it was possible to obtain a good multiplication rate without special problems for rooting or establishment in soil. To promote multiplication of axillary buds ; best results were obtained with Murashige and Skoog basal medium supplemented with Zuccherelli vitamins, NAA, GA and benzylaminopurine at concentrations 0,01, 0.1 and 5 mg/l. The nature of the iron supply seemed to be very important : thus Fe EDTA gave poor results with very chlorotic shoots, while Sequestrene 138 Fe (Ciba-Geigy) gave better results. From adult material, some fairly good results were obtained with the same culture medium but the method has to be improved for an intensive use

Asymmetric hybridization in Nicotiana by "gamma fusion" and progeny analysis of self-fertile hybrids

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Tomato flower abnormalities induced by stolbur phytoplasma infection are associated with changes of expression of floral development genes

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699International audienc

Metabolic complementation for a single gene function associated with partial and total loss of donor DNA in interspecific somatic hybrids

We report here on the obtainment of interspecific somatic, asymmetric, and highly asymmetric nuclear hybrids via protoplast fusion. Asymmetric nuclear hybrids were obtained after fusion of mesophyll protoplasts from a nitrate reductase-deficient cofactor mutant of N. plumbaginifolia with irradiated (100 krad) kanamycin resistant leaf protoplasts of a haploid N. tabacum. Selection for nitrate reductase (NR) and/or kanamycin (Km) resistance resulted in the production of three groups of plants (NR+, NR+, KmR, and NR-KmR). Cytological analysis of some hybrid regenerants showed the presence of numerous tobacco chromosomes and chromosome fragments, besides a polyploid N. plumbaginifolia genome (tetra or hexaploid). All the regenerants tested were male sterile but some of them could be backcrossed to the recipient partner. In a second experiment, somatic and highly asymmetric nuclear hybrids were obtained after fusion of mesophyll protoplasts from the universal hybridizer of N. plumbaginifolia with suspension protoplasts of a tumor line of N. tabacum. Selection resulted in two types of colonies: nonregenerating hybrid calli turned out to be true somatic hybrids, while cytological analysis of regenerants obtained on morphogenic calli did not show any presence of donor-specific chromosomes. Forty percent of the hybrid regenerants were completely fertile, while the others could only be backcrossed to the recipient N. plumbaginifolia. Since the gene we selected for is not yet cloned, we were not able to demonstrate the transfer of genetic material at the molecular level. However, since no reversion frequency for the nitrate reductase mutant is known, and due to a detailed cytological knowledge of both fusion partners, we feel confident in speculating that intergenomic recombination between N. plumbaginifolia and N. tabacum has occurred. © 1990 Springer-Verlag.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

The cell cycle-associated protein kinase WEE1 regulates cell size in relation to endoreduplication in developing tomato fruit

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Flower development schedule in tomato Lycopersicon esculentum cv. sweet cherry

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