The Arabidopsis flowering-time gene LUMINIDEPENDENS is expressed primarilyin regions of cell proliferation and encodes a nuclear protein that regulates LEAFY expression

Mutations in the LUMINIDEPENDENS (LD) gene of Arabidopsis thaliana (L.) Hey nh. (Arabidopsis) confer a late-flowering phenotype, indicating that LD nor mally functions to promote the floral transition. RNA and protein blot anal yses, along with the analysis of transgenic plants containing a fusion betw een a genomic fragment of LD and the reporter gene uidA (GUS), indicate tha t LD is expressed primarily in apical proliferative regions of the shoot an d root, including the shoot apical meristem and leaf primordia. Subcellular localization studies indicate that LD is a nuclear protein, consistent wit h its previously proposed transcriptional regulatory role. We have also fou nd that in an apetala 1 cauliflower (ap1 cal) background the Id mutation co nverts the reproductive shoot apex to a more vegetative state, a phenotype that is similar to that seen for the leafy (lfy) mutant. Furthermore, in si tu hybridization analysis indicates that LFY levels are drastically reduced at the apex of Id apl cal plants after bolting. These data are consistent with the idea that at least one function of LD is to participate in the reg ulation of LFY.