ILP5 promotes endoreduplication in Arabidopsis.

Abstract

Cells undergoing endoreduplication replicate chromosomal DNA without intervening mitosis. The resulting larger, higher ploidy nucleous is often associated with an increase in cell size. However, the molecular basis of endoreduplication remains poorly understood. To reveal the mechanism of endoreduplication, we screened activation tagging mutants that promote endoreduplication.
ilp5-D (increased level of polyploidy5-D) mutant was isolated as promoting endoreduplication. ilp5-D mutant showed cell expansion in several tissues, hypocotyls, cotyledon and tricome. ILP5 encoded unknown protein containing nuclei localizing signal. By BLAST search, ILP5 was similar to rice protein, but not to proteins of other organisms. Knock down of ILP5 gene results dwarf phenotype and decrease of poliploid level. These results indicated that ILP5 promote endoreduplication and regulate cell expansion.