Emergence of a resistance breaking isolate of Rice yellow mottle virus during serial inoculations is due to a single substitution in the genome-linked viral protein VPg

International audienceThe recessive gene rymv-1 responsible for the high resistance of Oryza sativa cultivar Gigante to Rice yellow mottle virus (Sobemovirus) was overcome by the variant CI4* which emerged after serial inoculations of the non-resistance-breaking (nRB) isolate CI4. By comparison of the full-length sequences of CI4 and CI4*, we identified a non-synonymous mutation at position 1729 localised in the putative VPg domain and developed an assay based on this single nucleotide polymorphism. The mutation G1729T was detected as early as the first passage in resistant plants and was found in all subsequent passages. Neither reversion nor additional mutation were observed. The substitution G1729T introduced by mutagenesis in the VPg of an nRB infectious clone is sufficient to induce symptoms in non-inoculated leaves of cultivar Gigante. This is the first evidence that VPg is a virulence factor in plants with recessive resistance against viruses outside the family Potyviridae

Rôle du récepteur kinase DMI2 dans la perception et la transduction du signal symbiotique Facteur Nod de Sinorhizobium meliloti chez la légumineuse Medicago truncatula

TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF

Les enfants de 7 à 9 ans dialoguent-ils avec un agent conversationnel comme avec un interlocuteur humain ?

National audienc

Les enfants de 7 à 9 ans dialoguent-ils avec un agent conversationnel comme avec un interlocuteur humain ?

National audienc

A role for RNA editing in the regulation of plastid-encoded polymerase activity

International audienc

Roles for RNA editing factors in leaf development

International audienc

Expression of the Medicago truncatula DMI2 gene suggests roles of the symbiotic nodulation receptor kinase in nodules and during early nodule development

The Medicago truncatula DMI2 gene encodes a receptorlike kinase required for establishing root endosymbioses. The DMI2 gene was shown to be expressed much more highly in roots and nodules than in leaves and stems. In roots, its expression was not altered by nitrogen starvation or treatment with lipochitooligosaccharidic Nod factors. Moreover, the DMI2 mRNA abundance in roots of the nfp, dmi1, dmi3, sp1, nsp2, and hcl symbiotic mutants was similar to the wild type, whereas lower levels in some dmi2 mutants could be explained by regulation by the nonsense-mediated decay, RNA surveillance mechanism. Using pDMI2::GUS fusions, the expression of DMI2 in roots appeared to be localized primarily in the cortical and epidermal cells of the younger, lateral roots and was not observed in the root apices. Following inoculation with Sinorhizobium meliloti, the DMI2 gene was induced in the nodule primordia, before penetration by the infection threads. No increased expression was seen in lateral-root primordia. In nodules, expression was observed primarily in a few cell layers of the pre-infection zone. These results are consistent with the DMI2 gene mediating Nod factor perception and transduction leading to rhizobial infection, not only in root epidermal cells but also during nodule development

Modélisation de dialogues pour personnage virtuel narrateur

International audienceDans l'optique de concevoir un agent conversationnel animé narratif et affectif, cet article montre l'importance de l'interaction dans le processus de narration à des enfants. Deux méthodes d'extraction de régularités ont été appliquées à des dialogues de narration parent-enfant afin de les modéliser. Les modèles extraits ont été évalués au cours d'une session de narration interactive de type Magicien d'Oz durant laquelle les enfants ont communiqué avec un personnage virtuel et un adulte en visio-conférence. L'expérience montre que les enfants s'engagent bien dans l'interaction avec le personnage virtuel mais que les modalités pour interagir diffèrent légèrement de celles utilisés avec l'adulte. ------------ To develop a narrative affective virtual agent, this article shows the importance of interaction modalities in storytelling environments. Building a narrative dialogue model requires a state transition that is computed automatically using various pattern extraction methods. These models are tested in a "Wizard-of-Oz" context, in a storytelling environment where the children are challenged to interact with a virtual character, by modelling several key points of interaction. We compare the level of engagement in two different narration contexts: virtual character or adult in video conference mode. Our experiments showed that the engagement exists, but the modality of the interaction feedback varies in the two contexts