Abstract
The high productivity of sweet potato (Ipomoea batatas) is due to the sink potential of storage root. Although the process of storage root development has been studied anatomically and physiologically, its molecular basis remains largely unknown. To identify the genes involved in the process, we isolated four knotted1-like homeobox (KNOX) sequences from the cDNA of developing storage root, and named Ibkn1 to Ibkn4. Phylogenetic analysis based on the homeodomain sequence showed that the Ibkn1 was homologous to the SHOOT-MERISTEMLESS gene of Arabidopsis. Also, Ibkn2 and Ibkn3 were homologous to the KNAT1 gene, and Ibkn4 was homologous to the KNAT2 gene. Expression analysis showed that Ibkn2, Ibkn3 and Ibkn4 were highly expressed at the stem and the storage root. Ibkn1 was also expressed at the stem, but its expression in the storage root was low. Further expression analyses are ongoing to elucidate the physiological function of these KNOX genes.
