Molecular Plant Pages 1–12, 2011 RESEARCH ARTICLE RPL1, a Gene Involved in Epigenetic Processes Regulates Phenotypic Plasticity in Rice

ABSTRACT Organisms can adjust their phenotype in response to changing environmental conditions. This phenomenon is termed phenotypic plasticity. Despite its ubiquitous occurrence, there has been very little study on the molecular mech-anismof phenotypic plasticity. In this study,we isolated a rice (Oryza sativa L.) mutant, rice plasticity 1 (rpl1), that displayed increased environment-dependent phenotypic variations. RPL1 was expressed in all tissues examined. The protein was localized in the nucleus and its distribution in the nucleus overlapped with heterochromatin. The rpl1 mutation led to an increase in DNA methylation on repetitive sequences and a decrease in overall histone acetylation. In addition, the mutation affected responses of the rice plant to phytohormones such as brassinosteroid, gibberellin, and cytokinin. Anal-ysis of the putative rice brassinosteroid receptor OsBRI1, a key hormone signaling gene, indicated that RPL1 may be in-volved in the regulation of epigenomic modification of the gene. These data suggest that RPL1 regulated phenotypic plasticity likely through its involvement in epigenetic processes affecting responses of the plant to phytohormones. Key words: Phenotypic plasticity; RPL1; epigenetics; phytohormone; evolution