Genetic transformation with a derivative of rolC from Agrobacterium rhizogenes and treatment with α-aminoisobutyric acid produce similar phenotypes and reduce ethylene production and the accumulation of water-insoluble polyamine-hydroxycinnamic acid conjugates in tobacco flowers

Abstract Tobacco plants were either transformed by rolA (ORF 10) or rolC (ORF 12) from the Ri TL-DNA of Agrobacterium rhizogenes , or they were treated with an inhibitor of ethylene production, α-AIB (α-aminoisobutyric acid). We recorded changes in phenotype, ethylene production and the accumulation of di- and polyamines, tyramine and their derivatives in excised flowers, as a function of floral development. Both α-AIB and the rolC gene (under the control of the 35S promoter from the CaMV virus) caused male sterility and a reduction in flower size, accompanied by a depression in the accumulation of water-insoluble polyamine and tyramine conjugates and a reduction in ethylene production. In plants transformed by 35S- rolC , we also observed narrowed leaves, reduced internode distance and changes in root system architecture. Transformation by 35S- rolA caused leaf wrinkling, internode shortening and downward bending of stamen filaments. We discuss these observations in the light of proposed functions for rolA and rolC and known relationships between polyamine and ethylene metabolism.