Abstract
Most monocotyledonous plants have perianth which are indistinguishable from petals; both are referred to tepals. The modified ABC model was hypothesized that the expansion of B class gene expression into whorl 1 was consistent with floral phenotypes in monocots. Recent studies of tulip and some liliaceaeous plants supported the modified ABC model. However, the study using plants with distinct morphologies of sepal and petal in monocots had not been made so far, how such differentiation have occurred in monocots remains unclear. To elucidate this question, we isolated and analyzed MADS-box genes from two commelinaceous flowers, Commelina and Tradescantia. We report five homologues of B class genes, moreover, RT-PCR using dissected floral organs showed that GLO-like gene expressed in all whorls but DEF-like gene in whorl 2 and 3. This result suggests that this reduction of DEF-like genes expression is correlated to the differentiation of sepal and petal in Commelinaceae.
