Abstract
Arabidopsis tfl2 mutants show an early-flowering and several other pleiotropic phenotypes. Molecular cloning of TFL2 shows that it encodes a protein with homology to HP1, which functions heterochromatin formation in animals. TFL2 protein localizes subnuclear in spot and TFL2 gene complements yeast swi6- mutant. These results suggest that TFL2 may function as HP1 in Arabidopsis. Global expression analyses using microarray, however, did not show the activation of genes in centromeric region nor in heterochromatic knob. Unexpectedly, we found the upregulation of several euchromatin genes; flowering gene, FT and floral homeotic genes, APETALA3, PISTILLATA, AGAMOUS, and SEPALLATA3. Ectopic expression of these genes are linked to the tfl2 phenotype and these genes regulate the critical aspects of Arabidopsis development. Our results demonstrate that TFL2 involves in the repression of specific euchromatin genes important for plant development rather than heterochromatin gene silencing in Arabidopsis.
