Abstract
Recently, increasing evidence indicates that siRNAs induce chromatin modifications and inactivation at genome of homologous sequences of siRNAs. Furthermore, the number of endogenous siRNAs is enormous and these sequences correspond to wide-rainging regions of the genome. However, if all of endogenous siRNAs induce chromatin modifications at homologous sequences, it may cause various defects.
We report here results of experiments designed to investigate whether siRNAs can induce chromatin modifications and inactivation in the genome of rice. We used a system in which exogenous siRNAs target promoter regions of genome. We chose 8 target genes, and analyzed target genes by examining chromatin inactivation, DNA methylation and histone modifications at respective target promoter regions. Our results suggest (1) siRNA is a strong inducer of DNA methylation; (2) siRNAs rarely induce histone modifications at the target genome; (3) siRNAs rarely induce chromatin inactivation at the target genome because of the lack of histone modifications.
