Global Characterization of DNA Methylation during Rice Leaf Angle Development

During plant development and growth, genomic DNA accumulates
chemical
markers that determine the levels of gene expression. DNA methylation
is an important epigenetic marker involved in plant developmental
events. However, the characterization of the role of DNA methylation
in rice leaf angle development has lagged behind. Herein, we performed
bisulfite sequencing to characterize DNA methylation sites and performed
transcriptome and small RNA sequencing during leaf angle development.
The results revealed a global reduction in CG methylation during leaf
angle establishment. A reduction in gene body CG methylation appears
to play a vital role in leaf angle development. The hypomethylated
and weakly expressed genes were functionally enriched in the brassinosteroid
and auxin signaling pathways. Additionally, the main DNA methyltransferases
were inactive. The addition of exogenous DNA methylation inhibitor
5-azacytidine increased the leaf angle, which confirmed that DNA methylation
is crucial for leaf angle development. This study revealed a gradual
decrease in 24-nucleotide siRNA levels during leaf angle development,
particularly in relation to the enrichment of 24-nucleotide siRNAs
at different hypomethylated regions that induce leaf angle inclination.
Our results indicate crucial roles for DNA methylation in the rice
leaf angle developmental stages.