A novel MADS-box gene of potato (Solanum tuberosum L.) expressed during the early stages of tuberization.

A potato MADS-box gene cDNA (POTM1-1) from an early tuber cDNA library has been isolated and characterized. The deduced amino acid sequence of POTM1-1 cDNA encodes 250 amino acids of a putative transcription factor containing a MADS-box domain and a K-box domain. These conserved domains share high homologies to those of flower-specific homeotic proteins, TM4 of tomato and AP1 of Arabidopsis, indicating that POTM1-1 gene is a homologue of the AP1 gene family. The levels of POTM1-1 transcripts were high in axillary buds, underground stolen tips, and newly formed tubers, but relatively low in mature tubers. During axillary bud development in a model petiole-leaf cutting system, the levels of POTM1-1 transcripts were abundant in actively growing shoots and during the early stages of microtuber development. It is possible that POTM1-1 functions as a transcription factor that regulates plant developmental processes in a number of tissue types.