Integration of banana streak badnavirus into the Musa genome: molecular and cytogenetic evidence.

Breeding and tissue culture of certain cultivars of bananas (Musa) have led to high levels of banana streak badnavirus (BSV) infection in progeny from symptomless parents. BSV DNA hybridized to genomic DNA of one such parent, Obino l'Ewai, suggesting integration of viral sequences. Sequencing of clones of Obino l'Ewai genomic DNA revealed an interface between BSV and Musa sequences and a complex BSV integrant. In situ hybridization revealed two different BSV sequence locations in Obino l'Ewai chromosomes and a complex arrangement of BSV and Musa sequences was shown by probing stretched DNA fibers. This is the first report of integrated sequences that possibly lead to a plant pararetrovirus episomal infection by a mechanism differing markedly from animal retroviral systems.