IbMADS4 regulates the vegetative shoot development in transgenic chrysanthemum (Dendrathema grandiflora (Ramat.) Kitamura)

14 A new MADS-box gene, IbMADS4, had been cloned in Ipomoea batatas (L.) Lam. that is expressed in all vegetative tissues of the plant, mainly in the root tissues, but not in flower organs. Sequence similarity besides the spatial and temporal expression patterns allows defining a novel MADS-box subfamily comprising STMADS16 and the other MADS-box genes expressed specifically in vegetative tissues. Expression of the IbMADS4 sense cDNA under the control of the 35S cauliflower mosaic virus promoter modifies dramatic changes in the phenotype, such as axillary shoot formation in chrysanthemum. Leaf and axillary shoot number of sense transgenic plants showed a three- and four-fold increase in shoot regeneration compared with the wild-type, respectively. The results presented here are aimed at understanding the molecular mechanisms involved in shoot morphogenesis. (C) 2003 Elsevier Ireland Ltd. All rights reserved.