Effects of Ri TL-DNA from Agrobacterium rhizogenes and the inhibitors of polyamine synthesis on growth, floral development, sexual organogenesis and polyamine metabolism in tobacco

Our recent work associated the phenotypic alterations caused by the Ri TL-DNA (root-inducing, left-hand, transferred DNA) from Agrobacterium rhizogenes with a general decrease in the accumulation of polyamines and their derivatives and showed that irreversible and specific inhibition of putrescine biosynthesis causes a phenotype similar to that attributed to the Ri TL-DNA. In this review we report recent data supporting a correlation between the degree of expression of the transformed phenotype due to the root-inducing, left-hand, transferred DNA and inhibition of polyamine accumulation, strongly suggesting that genes carried by the root-inducing, transferred DNA may act through interference with polyamine production via the ornithine pathway.