Abstract
Higher plants are constructed from billions of cells that have variable sizes and shapes. What controls these important cellular features are not well understood, but it is known that the total amount of nuclear DNA influence the final size of cells. In Arabidopsis, an increase in nuclear DNA content is mediated by a process called endoreduplication, however, the molecular mechanisms underlying this process is largely unknown. To gain new insights on the control of endoreduplication, we performed a new genetic screen to identify mutants that have altered plant size and ploidy. To date we have isolated four new mutations which we named high ploidy 1-4 (hip1-4). Endoreduplication in wild type seedlings usually brings the ploidy up to 32C. In contrast, we found that the ploidy levels in hip1-4 go up to 128C or 256C. Our current hypothesis is that HIP1-4 are involved in some pathways that negatively regulate endoreduplication.
