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The B genome of banana (Musa sp.) harbours integrations of Banana streak virus (eBSV) for at least three BSV species, whereas this badnavirus does not require integration for the replication of its ds DNA genome. Some are infectious by releasing a functional viral genome following stresses such as those existing in in vitro culture and interspecific crosses contexts. The structure of these eBSV is much longer than a single BSV genome, composed of viral fragments duplicated, more or less extensively rearranged containing at least one full length viral genome. Wild M. balbisiana diploid genotypes (BB) such as Pisang Klutuk Wulung (PKW) harbour such infectious eBSV belonging to three widespread species of BSV (Goldfinger -BSGFV, Imové - BSIMV and Obino l'Ewai - BSOLV) but are nevertheless resistant to any multiplication of BSV without any visible virus particles. Using deep sequencing of total siRNAs of PKW we underlined the presence of virus-derived small RNA (vsRNA) from eBSOLV, eBSGFV and eBSIMV by blasting sequences against the 3 BSV species genomes. Interestingly, we showed that hot and cold spots of vsRNA generation do not target similar viral sequences from one eBSV species to the other but are directly correlated with the structure of the integration. vsRNA are enriched in 24-nt class which represent about 75% of the total 21-24nt siRNA matching eBSV. We also demonstrated that eBSV are highly methylated in the three different sequence contexts (CG, CHH and CHG) throughout the whole sequence of eBSVs with no difference in methylation profile between siRNA producing and non producing areas. Interestingly, methylation patterns of all three eBSV are similar whereas they are located in different genomic context; eBSOLV being in a TE rich area whereas eBSIMV and eBSGFV are in genes rich region. It seems that eBSV are controlled mainly by epigenetic mechanisms similar to those described for transposable elements (TE). All together, our data indicate that eBSVs in PKW

The B genome of banana (Musa sp.) harbours integrations of Banana streak virus (eBSV) for at least three BSV species, whereas this badnavirus does not require integration for the replication of its ds DNA genome. Some are infectious by releasing a functional viral genome following stresses such as those existing in in vitro culture and interspecific crosses contexts. The structure of these eBSV is much longer than a single BSV genome, composed of viral fragments duplicated, more or less extensively rearranged containing at least one full length viral genome. Wild M. balbisiana diploid genotypes (BB) such as Pisang Klutuk Wulung (PKW) harbour such infectious eBSV belonging to three widespread species of BSV (Goldfinger -BSGFV, Imové - BSIMV and Obino l'Ewai - BSOLV) but are nevertheless resistant to any multiplication of BSV without any visible virus particles. Using deep sequencing of total siRNAs of PKW we underlined the presence of virus-derived small RNA (vsRNA) from eBSOLV, eBSGFV and eBSIMV by blasting sequences against the 3 BSV species genomes. Interestingly, we showed that hot and cold spots of vsRNA generation do not target similar viral sequences from one eBSV species to the other but are directly correlated with the structure of the integration. vsRNA are enriched in 24-nt class which represent about 75% of the total 21-24nt siRNA matching eBSV. We also demonstrated that eBSV are highly methylated in the three different sequence contexts (CG, CHH and CHG) throughout the whole sequence of eBSVs with no difference in methylation profile between siRNA producing and non producing areas. Interestingly, methylation patterns of all three eBSV are similar whereas they are located in different genomic context; eBSOLV being in a TE rich area whereas eBSIMV and eBSGFV are in genes rich region. It seems that eBSV are controlled mainly by epigenetic mechanisms similar to those described for transposable elements (TE). All together, our data indicate that eBSVs in PKW

The genome of banana (Musa sp.) harbours multiple integrations of Banana streak virus (BSV), whereas this badnavirus does not require integration for the replication of its ds DNA genome. Some endogenous BSV sequences (eBSV), only existing in the Musa balbisiana genome, are infectious by releasing a functional viral genome following stresses such as those existing in in vitro culture and interspecific crosses context. The structure of these eBSV is much longer than a single BSV genome, composed of viral fragments duplicated and more or less extensively rearranged. Wild M. balbisiana diploid genotypes (BB) such as Pisang Klutuk Wulung (PKW) harbour such infectious eBSV belonging to three widespread species of BSV (Goldfinger -BSGFV, Imové - BSImV and Obino l'Ewai - BSOLV) but are nevertheless resistant to any multiplication of BSV without any visible virus particles. We postulated these eBSV induced a natural resistance driven by gene silencing mechanisms based on their complex molecular re-arranged structure which could lead to dsRNA hairpins formation. In collaboration with the group headed by M. Pooggin (Basel, Switzerland), a deep sequencing of total siRNAs of PKW was performed using the Illumina ultra-high-throughput technology. We obtained for the first time, experimental evidence of virus-derived small RNA (vsRNA) from BSOLV, BSGFV and BSImV by blasting sequences against the 3 BSV species genomes. vsRNA are enriched in 24-nt class thus eBSV in PKW genome are likely silenced at the transcriptional level. A repartition of the vsRNA population matching eBSV will be also presented in order to determine hot and cold spots of vsRNA generation. (Texte intégral)

The genome of banana (Musa sp.) harbours multiple integrations of Banana streak virus (BSV), whereas this badnavirus does not require integration for the replication of its ds DNA genome. Some endogenous BSV sequences (eBSV), only existing in the Musa balbisiana genome, are infectious by releasing a functional viral genome following stresses such as those existing in in vitro culture and interspecific crosses context. The structure of these eBSV is much longer than a single BSV genome, composed of viral fragments duplicated and more or less extensively rearranged. Wild M. balbisiana diploid genotypes (BB) such as Pisang Klutuk Wulung (PKW) harbour such infectious eBSV belonging to three widespread species of BSV (Goldfinger -BSGFV, Imové - BSImV and Obino l'Ewai - BSOLV) but are nevertheless resistant to any multiplication of BSV without any visible virus particles. We postulated these eBSV induced a natural resistance driven by gene silencing mechanisms based on their complex molecular re-arranged structure which could lead to dsRNA hairpins formation. In collaboration with the group headed by M. Pooggin (Basel, Switzerland), a deep sequencing of total siRNAs of PKW was performed using the Illumina ultra-high-throughput technology. We obtained for the first time, experimental evidence of virus-derived small RNA (vsRNA) from BSOLV, BSGFV and BSImV by blasting sequences against the 3 BSV species genomes. vsRNA are enriched in 24-nt class thus eBSV in PKW genome are likely silenced at the transcriptional level. A repartition of the vsRNA population matching eBSV will be also presented in order to determine hot and cold spots of vsRNA generation. (Texte intégral)