Accumulation of the long class of siRNA is associated with resistance to Plum pox virus in a transgenic woody perennial plum tree

• Published in: Molecular plant-microbe interactions Vol. 18; no. 8; pp. 794 - 799
• Main Authors: HILY, Jean-Michel, SCORZA, Ralph, WEBB, Kevin, RAVELONANDRO, Michel
• Format: Journal Article
• Language: English
• Published: St Paul, MN APS Press 01.08.2005; American Phytopathological Society
• Subjects: Biochemistry, Molecular Biology; Biological and medical sciences; Fundamental and applied biological sciences. Psychology; Genes, Viral; Life Sciences; Phytopathology. Animal pests. Plant and forest protection; Plant Diseases - genetics; Plant Diseases - virology; Plant Leaves - metabolism; Plant viruses and viroids; Plants, Genetically Modified; Plum pox virus; Plum Pox Virus - physiology; Prunus; Prunus - genetics; Prunus - virology; RNA, Messenger - metabolism; RNA, Small Interfering - genetics; RNA, Small Interfering - metabolism; RNA, Viral - metabolism; Seedlings - metabolism; Seeds - metabolism; Wood; Embryo; Plant pathogen; Microbiology; Prunus domestica; Transcription; Germination; Rosaceae; Protein; Seedlings; Virus; Resistance; Gene silencing; Plant; Plum pox virus; Dicotyledones; Angiospermae; Spermatophyta; Fruit tree; Potyvirus; Methylation; Potyviridae; POTYVIRUS; SILENCING; PPV; PRUNIER; SIRNA; MALADIE DES PLANTES; PLUM POX VIRUS
• ISSN: 0894-0282; 1943-7706
• DOI: 10.1094/MPMI-18-0794

We investigated the hallmarks of posttranscription gene silencing (PTGS) in mature plants, embryos, and seedlings of the transgenic plum trees (Prunus sp.) that are resistant to Plum pox virus (PPV). We previously demonstrated that the transgene insert and resistance to PPV were mutually inherited in progeny of line C5. We show here that C5 constitutively produces a short (22 nt) and a long (25 to 26 nt) species of short interfering (si)RNA from embryo to mature plant in the absence of PPV inoculation. Unlike siRNA, methylation and transcription of the PPV-coat protein transgene were 're-set' following seed germination. Uninoculated transgenic susceptible clones did not display DNA methylation, nor did they produce detectable levels of siRNA. Upon infection, susceptible clones, transgenic or untransformed, did produce siRNA but only the short 22-nt species. These findings show that plum trees respond to virus infection by initiating PTGS-like mechanisms that involve the production of siRNA. We further suggest that high-level virus resistance in transgenic Prunus species requires the production of the long-size class of siRNA. The research adds new insights into PTGS silencing in woody perennial plant species.