Agrobacterium rhizogenes ( rhizobiacease ) is a kind of gram - negative bacterium , which contains a big ri plasmid ( 200kb ) - root inducing plasmid . there are three types of ri plasmid , mannopine type , cucumopine type and agropine type , according to the type of opine synthesized in transgenic cell 根據轉化細胞合成的冠癭堿( opine )的類型不同, ri質粒分為3種類型:甘露堿型( mannopinetype ) 、黃瓜堿型( cucumopinetype )和農桿堿型( agropinetype ) 。