Constitutive expression of rice ORGAN SIZE RELATED genes in Arabidopsis results in organ size enlargement

Abstract

In plants, organ size control is a fundamental process during development. The Arabidopsis ORGAN SIZE RELATED (OSR) gene family plays a key role in organ size regulation. To explore the roles of OSR orthologs in rice, a BLAST search in the rice genome was performed and five putative OSR orthologs were isolated and designated as OsOSR. Constitutive expression of OsOSR1, OsOSR2 and OsOSR4 in Arabidopsis resulted in enlarged organ sizes, as a consequence of enhanced cell number and cell size, while the increase of organ size in the OsOSR3 and OsOSR5-expressing plants was only due to cell enlargement. Our results suggest that the rice OsOSR genes possess the conserved organ growth-promoting function and may be involved in the coordination of cell proliferation and expansion during plant development.