La distinction des variétés de luzerne pourrait s’appuyer sur les marqueurs moléculaires

La distinction des variétés de luzerne pourrait s’appuyer sur les marqueurs moléculaires. 2. Rencontres Francophones sur les Légumineuses (RFL2

Introduced hybrid ash : Fraxinus excelsior x F. angustifolia in Ireland and its potential for interbreeding with native ash

THESIS 9556Fraxinus excelsior L. is the only native ash in Ireland. It has important economic value for timber exploitation. After the introduction of grants by Irish government in the 1990s for planting native broadleaf trees, with an extra premium of hardwood species including ash, provenances of supposed F. excelsior were imported from continental Europe to fulfil the needs of foresters and farmers. At the time of planting, the trees appeared to be of excellent quality but after some years, the trees started to show very bad stem form, poor vigour and growth, and unusual morphology. Management authorities, farmers and foresters have questioned the authenticity and origin of the imported trees. Indeed very pale and brown buds observed on introduced trees are more characteristic of another species F. angustifolia Vahl present in continental Europe, with usually a more southern distribution than F. excelsior. Moreover, natural hybrids between these two species have been observed in two different zones where the species grow in sympatry. Reciprocal artificial crosses have also been made

Métrologie à SOLEIL. Des outils de mesure de la forme des miroirs synchrotron : un microscope interférométrique à balayage de phase et raccordement de champ

La cohérence des nouvelles sources synchrotron nécessite l’utilisation d’optiques limitées par la diffraction à des longueurs d’ondes inférieures au nanomètre. La fabrication des surfaces optiques a énormément progressé ces dernières années grâce aux techniques de polissage déterministe. Des surfaces avec des défauts de moins de 1 nm de hauteur pour des fréquences spatiales de l’ordre de 1 mm peuvent être actuellement produites. Le synchrotron SOLEIL ne possède pas le moyen de produire de telles optiques mais se doit d’être capable de les contrôler avant leur montage sur les lignes de lumière

pur4 Mutations Are Lethal to the Male, But Not the Female, Gametophyte and Affect Sporophyte Development in Arabidopsis[C][W]

Purine metabolism is crucial in living cells and involves three complex pathways in plants: the de novo synthesis, the salvage, and the degradation pathways. The relative importance of each pathway in plant development and reproduction, however, is still unclear. We identified two T-DNA insertions in the Arabidopsis (Arabidopsis thaliana) PUR4 gene (At1g74260) that encodes formylglycinamidine ribonucleotide synthase (EC 6.3.5.3), the fourth enzyme in the de novo purine biosynthesis pathway. The mutated alleles were never transmitted through the pollen of heterozygous plants but could be inherited through the female gametophyte, indicating that de novo purine synthesis is specifically necessary for pollen development. Because the pur4 mutations were lethal to the male gametophyte, homozygous pur4 plants could not be obtained. However, the reproductive phenotype of hetererozygous plants carrying the pur4-2 mutated allele was more severe than that carrying the pur4-1 mutated allele, and pur4-2/+ plants showed slightly delayed early development. We showed that the pur4-2 allele produces an antisense transcript and that the amount of PUR4 mRNA is reduced in these plants. Transient expression of a translational fusion with the green fluorescent protein in Arabidopsis plantlets showed that the formylglycinamidine ribonucleotide synthase protein is dually targeted to chloroplast and mitochondria, suggesting that at least some steps of the de novo purine biosynthesis pathway can take place in both organelles in Arabidopsis, a dual location previously thought to be a peculiarity of ureide-forming tropical legumes

Use of GBS for lucerne variety distinction

Distinctness among lucerne varieties, evaluated in DUS tests, is a frequent obstacle to variety registration. Promising varieties may fail the distinction test despite an agronomic plus-value so the genetic progress is not delivered to farmers. The Genotyping By Sequencing (GBS) technology that enables to obtain a large number of markers on pools of individuals was used to evaluate the distinction among 20 lucerne varieties of the European Catalogue. A total of 40 000 polymorphic markers was obtained. All the varieties were statistically different from the others, and the structure was consistent with knowledge on the varieties. Perspectives to use GBS in DUS testing are given

Use of GBS for lucerne variety distinction

International audienc

Use of GBS for lucerne variety distinctness

National audienc

Use of GBS markers to distinguish among lucerne varieties, with comparison to morphological traits

International audienceVariety registration of lucerne often fails because of the difficulty to pass the distinction test. This test is presently based on phenotypic traits. We proposed to evaluate if high-throughput genotyping of varieties with genotyping-by-sequencing markers could help to distinguish among 20 varieties and if the genetic distances were correlated to phenotypic ones. Genotyping was performed either on 40 individuals or on 4 bulks of 100 plants per variety. At the methodological level, we obtained a high number of polymorphic markers, a precise determination of the allele dosage on the individuals, a high reproducibility of allele frequency estimated on bulks and a good correlation between allele frequencies scored on individuals or on bulks. Each pair of the 20 varieties was significantly distinct when using the markers. In addition, the varieties grouped in a way that was consistent with their genetic origin. Genetic distances were correlated to phenotypic distances obtained from data collected in the distinction tests. We suggest that molecular markers could be useful to assist distinction tests during the official trials for registration of lucerne varieties