Arabidodsis histone H2A mutant is deficient in Agrobacterium T-DNA integration

摘要

Agrobacterium tumefacfens genetically transforms plant cells by transferring a portion of the bacterial Ti-plasmid, the T-DNA. to the plant and integrating the T-DNA into the plant genome. Little is known about the T-DNA integration process, and no plant genes involved in integration have yet been identified. We characterized an Arabisis mutant generated by T-DNA insertional mutagen- esis. rat5 that is resistant to Agrobacterium root transformation. rat5 contains two copies of T-DNA integrated as a tandem direct repeat into the 3' untranslated region of a histone H2A gene. upstream of the polyadenylation signal sequence. Transient and stable p-glucuronidase expression data and assessment of the amount of T-DNA integrated into the genomes of wild-type and rat5 Arabtwsis plants indicated that the rat5 mutant is deficient in T-DNA integration. We complemented the rat5 mutation by expressing the RAT5 histone H2A gene in the mutant plant. Overexpression of RAT5 in wild-type plants increased Agrobacte- rnim transformation efficiency. Furthermore. transient expression of a RAT5 gene from the incoming T-DNA was sufficient to complement the rat5 mutant and to increase the transformation efficiency of wild-type Arabidopsis plants.