Transgenic plants altered in phytohormone metabolism

Abstract

Summary Genes cloned from microbial plant pathogens have been expressed in transgenic plants to provide evidence that plant physiological and developmental processes can be altered by enzymes either able to synthesize auxinconjugates (e.g. indolacetic-acid-lysine synthetase from Pseudomonas savastanoi) or to release free active cytokinins from their inactive conjugates (e.g. RolC β-glucosidase of Agrobacterium rhizogenes). Alteration of phytohormone metabolism (i.e. auxin) results from the anther—specific expression of the rolB gene of Agrobacterium rhizogenes, which codes for a s-glucosidase able to hydrolyse indoxyl-glucoside. Plants, which are mosaics for the expression of a cytokinin—synthesising enzyme (i.e. isopentenyltransferase of Agrobacterium tumefaciens) form adventitious buds on their leaves indicating that in planta cytokinin can trigger a novel and ectopic developmental plan. Epiphyllous buds are usually vegetative. However, floral buds are observed too. Some epiphyllous floral buds are morp...