Integration patterns of Banana streak virus into banana nuclear genome [S25-10]

Bananas are the developing world's fourth most important food crop. Many cultivated genotypes are hybrids between Musa acuminata (A genome) and M. balbisiana (B genome). Banana streak virus (BSV) is the causal agent of viral leaf streak of banana and plantain. Recently, it was demonstrated that BSV sequences are integrated into the banana genome and there is strong experimental evidence that these "integrants" can yield an infectious episomal viral genome via homologous recombination. In order to better define integration patterns of BSV into banana nuclear genome, we have constructed three BAC libraries from M. acuminata Cavendish, M. acuminata Calcutta 4 and M. balbisiana PKW, respectively. These BAC libraries were constructed by partial digestion of genomic DNA with HindIII restriction enzyme and its cloning into the pIndigoBAC-5 vector. Three different BSV strains (BSV-OL "Obino L'Ewai", BSV-GF "Gold Finger", BSV-IM "Imove") were used as probes to test the presence of integrated viral sequences in the nuclear genome of banana and plantain species. Upon BAC library screening we identified 10 BAC clones positive for BSV-OL, 9 BAC clones positive for BSV-GF and 24 BAC clones positive for BSV-IM in the M. balbisiana (BB) PKW BAC library. On the other hand, the screening of M. acuminata Calcutta4 (AA) and M. acuminata Cavendish (AAA) BAC libraries with the three complete viral sequences revealed no BAC clones containing BSV sequences. This study represent the first step towards the characterization of BSV "integrants" and definition of mechanisms leading to activation of integrated viral sequences upon stress conditions. This project is supported by CIRAD, INIBAP, Agropolis International and Cinvestav- Mexico. (Texte intégral