Citrus tristeza virus (CTV) is a filamentous virion (genus Closterovirus, family Closteroviridae) that contains a single-stranded, positive-sense RNA genome of 19.3 kb consisting of 12 open reading frames (ORFs). CTV is the responsible of the current devastation of cultivated citrus trees especially of the widely used rootstock sour orange (Citrus aurantium), which appears to be one of the most susceptible species causing severe economic losses. Moreover, the relative species of trifoliate orange (Poncirus trifoliata) appears to be resistant to the disease while, the Citrange carrizo, derived from the cross between C. sinensis L. x P. trifoliate, appears to be tolerant. The resistance to the virus is due to the presence of a locus, called Ctv locus, which is available an accurate genetic map. Eight retrotransposons, 61 Simple Sequence Repeats (SSRs), more than 400 Miniature Inverted-repeats transposable Elements (mites) and several genes, with a high homology sequence to known function genes of other species are present into the Ctv locus. Among these the Ctv.20 gene showed homology with a plant virus movement-like protein. This membrane protein is involved, through the formation of channels in plasmodesma, in the protein transfer and viral RNA movement from cell to cell. The aim of the present work was to carry out different siRNA 21:24 nucleotides libraries by Illumina sequencing, from susceptible plants of sour orange and tolerant of Citrange carrizo ones, both healthy and infected with different strains of CTV virus. The presence of a homologous locus in susceptible species such as Citrus aurantium suggests that the mechanisms of resistance and therefore of regulating the expression of the genes present in the locus cannot be fully explained by DNA sequence alone. On this basis we moved to verify the role of siRNA through an epigenetic regulation of the methylation status of Ctv locus. The difference between methylated and unmethylated condition in tolerant and susceptible plants was performed by PCR analysis on DNA digested by sensitive and unsensitive enzymes to cytosine methylation

THE ROLE OF siRNA THROUGH AN EPIGENETIC REGULATION OF THE METHYLATION STATUS OF CTV LOCUS

FANELLI V;GIAMPETRUZZI, ANNALISA;LOCONSOLE, GIULIANA;MONTEMURRO, CINZIA;DE GIOVANNI, Claudio;
2013

Abstract

Citrus tristeza virus (CTV) is a filamentous virion (genus Closterovirus, family Closteroviridae) that contains a single-stranded, positive-sense RNA genome of 19.3 kb consisting of 12 open reading frames (ORFs). CTV is the responsible of the current devastation of cultivated citrus trees especially of the widely used rootstock sour orange (Citrus aurantium), which appears to be one of the most susceptible species causing severe economic losses. Moreover, the relative species of trifoliate orange (Poncirus trifoliata) appears to be resistant to the disease while, the Citrange carrizo, derived from the cross between C. sinensis L. x P. trifoliate, appears to be tolerant. The resistance to the virus is due to the presence of a locus, called Ctv locus, which is available an accurate genetic map. Eight retrotransposons, 61 Simple Sequence Repeats (SSRs), more than 400 Miniature Inverted-repeats transposable Elements (mites) and several genes, with a high homology sequence to known function genes of other species are present into the Ctv locus. Among these the Ctv.20 gene showed homology with a plant virus movement-like protein. This membrane protein is involved, through the formation of channels in plasmodesma, in the protein transfer and viral RNA movement from cell to cell. The aim of the present work was to carry out different siRNA 21:24 nucleotides libraries by Illumina sequencing, from susceptible plants of sour orange and tolerant of Citrange carrizo ones, both healthy and infected with different strains of CTV virus. The presence of a homologous locus in susceptible species such as Citrus aurantium suggests that the mechanisms of resistance and therefore of regulating the expression of the genes present in the locus cannot be fully explained by DNA sequence alone. On this basis we moved to verify the role of siRNA through an epigenetic regulation of the methylation status of Ctv locus. The difference between methylated and unmethylated condition in tolerant and susceptible plants was performed by PCR analysis on DNA digested by sensitive and unsensitive enzymes to cytosine methylation
978-88-904570-3-6
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11586/137122
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