Figure 2: Active site of Osa is essential for T-DNA transfer in vivo.

Results of GUS (β-glucuronidase) assay after agroinfiltration of Nicotiana tabaccum leaf discs are shown. Blue-green colour indicates GUS expression, and thus transfer of gus gene flanked with T-DNA borders from Agrobacterium into plant. Blank: Agrobacterium resuspension buffer, Mock: Agrobacterium tumefaciens LBA4404 strain alone, Control: LBA4404 containing pCAMBIA1301 and pSoup vector alone, without any insert. Test experiments had Agrobacterium clones harbouring pCAMBIA1301 and pSoup containing either Osa or one of its mutants, or other FINs—ICE1056Fin, FipA and PifC.