Summary

Clone O39 Encodes a Homeobox Transcription Factor

Clone O39 represents a full-length mRNA of 3088 that encodes a homeodomain protein with a calculated molecular weight of approximately 84 kD. O39 exhibits little sequence similarity to other homeodomain proteins outside the homeobox region with the notable exception of GLABRA2, a homeodomain protein that regulates trichome differentiation in Arabidopsis . For further detail, please see our publication by (Nadeau, Zhang, Li and O'Neill, 1996).

Analysis of Gene Expression

In Phalaenopsis , the commitment to ovule development occurs between 4 and 5.5 WAP (See Time Line). When meristematic projections from the placental region are present but no obvious differentiation into ovule primordia has occurred, there is also no expression of O39 transcripts. At or near 5.5 WAP, most ovule primordia contain differentiated archesporial cells and are undergoing the first periclinal divisions of the protoderm to form integuments (Panel A). Significantly, O39 gene expression is first noted at this time, after commitment to the program of ovule development has most likely occurred (Panel B). In situ hybridization analysis demonstrates that the O39 transcript is present throughout the ovule primordium at early stages, as well as throughout the various differentiating ovule tissues at later stages of development .