Abstract
Endoreduplication is a special cell cycle containing DNA replication in the absence of mitosis. In higher plants, it is known that endoreduplication affects its morphogenesis because increases in the ploidy are often related to cell size. But, little is known about the molecular mechanism.
To reveal this mechanism, we analyzed a Arabidopsis mutant, increased level of polyploidy4-D (ilp4-D), which was isolated from activation tagging lines. ilp4-D showed increased polyploidy in the seedlings. ILP4 gene encodes a protein that contains a kinase domain. Histochemical analysis using a ILP4 promoter-GUS reporter gene showed GUS activity in root, cotyledon and hypocotyls, suggesting ILP4 expression has tissue specificity.
T-DNA insertion lines of ILP4 were did not show any obvious phenotype. There are two ILP4 homologue, ILP4L1 and ILP4L2, in Arabidopsis. ILP4 and ILP4L1 double mutant showed decreased polyploidy level in dark seedlings. These results indicated ILP4 and ILP4L1 promote endocycle.
