A new MADS-box gene, STMADS16, has been cloned in Solanum tuberosum L. that is expressed in all vegetative tissues of the plant, mainly in the stem, but not in flower organs. STMADS16 expression is established early during vegetative development and is not regulated by light. Sequence similarity besides the spatial and temporal expression patterns allow to define a novel MADS-box subfamily comprising STMADS16 and the gene STMADS11. Expression of the STMADS16 sense cDNA under the control of the 35S cauliflower mosaic virus promoter modifies the inflorescence structure by increasing both internode length and flower proliferation of the inflorescence meristems, and confers vegetative features to the flower. Moreover, STMADS16 ectopic expression overcomes the increase in flowering time and node number produced under short-day photoperiod, while the flowering time is not affected in long-day conditions. These results are discussed in terms of a possible role for STMADS16 in promoting vegetative development.

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