Viroids; Plant-interaction; gene silencing; Protein interaction; peach tree disease
Abstract :
[en] Viroids are non encapsidated small RNA plant pathogens unable to produce any protein. They are able to infect dramatically a broad range of plants including herbaceous and tree crops. The ways by which viroids are able to induce diseases are actually unknown. However, recent studies have shown that viroids are able to regulate the gene expression of their hosts, they can modify the host-protein phosphorylation sensibility and they interact with host-protein implicated RNA trafficking and protein phosphorylation. Moreover during their evolution plants have developed a mechanism able to regulate their gene expression and to degrade exogenous RNAs like viroids: the gene silencing. Unfortunately, this pathway seems, now, also highly implicated in the symptoms development. This review describes studies that are realized since a few years to increase the knowledge about the plant-viroid relationship. [fr] Les viroïdes sont des petits ARNs pathogènes de nombreuses cultures herbacées ou ligneuses non encapsidés et ne codant pour aucune protéine. La façon dont les viroïdes induisent des maladies est encore très peu connue. Cependant, des études récentes ont montré que les viroïdes étaient capables de modifier l’expression des gènes de leur plante hôte, de modifier la sensibilité de certaines protéines à la phosphorylation, d’interagir avec des protéines de l’hôte impliquées dans le mouvement des ARN et dans la phosphorylation des protéines. De plus, les végétaux possèdent un mécanisme de défense vis-à-vis d’ARN exogène : l’extinction de gène. Ce mécanisme, stimulé lors d’infections viroïdales, est en outre capable de réguler l’expression des gènes endogènes et serait impliqué dans l’expression des symptômes dus aux viroïdes. Depuis quelques années, des études sont réalisées afin de comprendre les relations hôte-pathogène s’établissant entre les viroïdes et leurs hôtes.
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