Arabidopsis SGS2 and SGS3 Genes Are Required for Posttranscriptional Gene Silencing and Natural Virus Resistance

• Published in: Cell Vol. 101; no. 5; pp. 533 - 542
• Main Authors: Mourrain, Philippe, Béclin, Christophe, Elmayan, Taline, Feuerbach, Frank, Godon, Christian, Morel, Jean-Benoit, Jouette, David, Lacombe, Anne-Marie, Nikic, Snezana, Picault, Nathalie, Rémoué, Karine, Sanial, Mathieu, Vo, Truy-Anh, Vaucheret, Hervé
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 26.05.2000; Elsevier
• Subjects: Amino Acid Sequence; Arabidopsis; Arabidopsis - enzymology; Arabidopsis - genetics; Arabidopsis Proteins; Arabidopsis thaliana; Base Sequence; Cellular Biology; Chromosome Mapping; Cloning, Molecular; Cucumovirus; DNA, Plant; EGO-1 protein; Gene Silencing; Genes, Plant; Life Sciences; Lycopersicon esculentum - enzymology; Molecular Sequence Data; Mutagenesis; Plant Diseases - virology; Plant Proteins - genetics; Plant Proteins - metabolism; Potyvirus; QDE-1 protein; RNA Processing, Post-Transcriptional; RNA Replicase - genetics; RNA Replicase - metabolism; SGS2 gene; SGS2 protein; SGS3 gene; Tobamovirus; GENETIQUE
• ISSN: 0092-8674; 1097-4172
• DOI: 10.1016/S0092-8674(00)80863-6

Posttranscriptional gene silencing (PTGS) in plants results from the degradation of mRNAs and shows phenomenological similarities with quelling in fungi and RNAi in animals. Here, we report the isolation of sgs2 and sgs3 Arabidopsis mutants impaired in PTGS. We establish a mechanistic link between PTGS, quelling, and RNAi since the Arabidopsis SGS2 protein is similar to an RNA-dependent RNA polymerase like N. crassa QDE-1, controlling quelling, and C. elegans EGO-1, controlling RNAi. In contrast, SGS3 shows no significant similarity with any known or putative protein, thus defining a specific step of PTGS in plants. Both sgs2 and sgs3 mutants show enhanced susceptibility to virus, definitively proving that PTGS is an antiviral defense mechanism that can also target transgene RNA for degradation.