Abstract
During leaf development, a decrease in cell number often triggers an increase in cell size. This phenomenon, called compensation, suggests the presence of systems that coordinate cell proliferation and expansion. We have isolated five fugu mutants of Arabidopsis thaliana that exhibit compensation, and identified that fugu2 is a novel allele of fasciata1 (fas1). Our micro-array analysis revealed that the expression level of 46 genes is up-regulated in fas1 leaves, and that most of them overlapped with a group of genes that respond to DNA damage. Together, these results suggest that cell cycle arrest triggered by DNA damage response may eventually lead to promotion of endocycle which in turn enhances cell expansion in fas1. To examine this hypothesis, we performed genetic analysis between fas1 and DNA damage response mutants. Among them, atr mutation suppressed compensated cell expansion of fas1. We are now trying to gain further insights into compensation of fas1. Based on these results, we will discuss the role of DNA damage response in organ size control.
