Compensated cell enlargement is induced postmitotically in fugu mutants and is mediated by two different expansion-regulatory pathways

Abstract

In Arabidopsis several mutations that decrease cell proliferation activity often trigger excessive cell enlargement, a phenomenon that we named as compensation. However, the nature of such organ-wide coordination between cell proliferation and expansion is still obscure. We isolated and characterized six mutants fugu1- fugu5 and erecta, together with an3 and KRP2 overexpressor, all of which exhibit compensation. Time course analysis of leaf development revealed postmitotic cell enlargement is mediated by either an increase in the rate or duration of cell expansion in fugu2 and fugu5, respectively. Thus, we chosed these two mutants for further analyses. As the first step of such studies, DNA microarray analysis where fugu2 and fugu5 were used as representatives revealed that substantially different sets of genes were affected between fugu2 and fugu5. Map-based cloning of FUGU2 gene revealed that it is the FASCIATA1 gene. We will discuss possible mechanisms of compensation based on our recent findings.