Germinal Virus Vector WDV (Wheat Dwarf Virus)-Mediated Multiple Insertions of a Maize transposon, Ds (Dissociation), in Rice

Abstract

Wheat dwarf virus (WDV) is a monocot-infecting geminivirus that replicates in infected tissue as double-stranded DNA. We evaluated whether the WDV vector system bearing Ds could be used as an effective insertional mutagen in rice. Molecular data showed that Ds was excised from WDV vectors once the WDV-carrying DS (WDV::Ds) and the genomic Ac vector were co-introduced into rice calli. Mature To and T1 transgenic plants were analyzed for the distribution and inheritance of Ds inserts. Southern analysis indicated that the Ds elements excised from WDV vectors were stably inserted into genomes. The number of transposed Ds ranged from zero to three copies, among independent transformants. Meanwhile, untransposed Ds (WDV::DS) were present in multiple-copies in genomes. Southern analysis of the selfed progeny of TO plants demonstrated that most WDV::Ds were co-segregated among sibling. This indicated that these elements were integrated into the same single loci. However, a few Ds were found to segregate independently from the majority of Ds. In this report, we discuss the efficiency of WDV vectors in generating multicopy Ds in rice genomes.