Isolation of MaDEF from Muscari armeniacum and analysis of its expression using laser microdissection

In higher eudicot, the floral organs consist of four different whorls, containing sepals, petals, stamens and carpels. In contrast, the perianths of many monocotyledonous plants, like Liliaceae plants, have almost identical petaloid organs called tepals. The modified ABC model explains this flower morphology; class B genes are expressed in whorl 1 as well as whorls 2 and 3, resulting that the two outer whorls are almost identical petaloid organs. Expression pattern of class B genes in tulip supports this modified ABC model, however, the expression of asparagus class B genes were restricted in the inner tepals and stamens. To investigate whether the class B gene expression pattern of asparagus is shared by related species, the class B gene MaDEF was isolated from Muscari armeniacum, belonging to the order Asparagales. RT-PCR showed that MaDEF is expressed in outer tepals as well as in inner tepals and stamens. This expression pattern is consistent with that of tulip, supporting the modified ABC model in M. armeniacum. Since M. armeniacum flower buds are too small for accurate separation into individual floral organs, the laser microdissection (LMD) system was used to isolate floral organ-specific RNA. We also discuss the suitability of the LMD technique for plant research.