Abstract
Endoreduplication is specific cell cycle that replicates chromosomal DNA without intervening mitosis. Higher ploidy nuclei are often associated with cell morphogenesis. In higher plant, endoreduplication occurs almost all tissues, and regulates cell elongation and differentiation. However, the molecular mechanism of endoreduplication remains poorly understood.
To reveal the mechanism of endoreduplication, we screened about 4500 activation tagged mutants that promote ploidy level using flow-cytometer. ilp5-D (increased level of polyploidy5-D) mutant was isolated as promoting ploidy level. ilp5-D mutant showed cell expansion in several tissues, hypocotyls, cotyledon and tricome. ILP5 encoded unknown function protein containing nuclei localizing signal. By histochemical analysis, ILP5 especially expressed rapid cell elongation tissues. Knock down of ILP5 gene results dwarf phenotype and decrease of poliploid level. These results indicated that ILP5 promote endoreduplication and regulate cell expansion.
