Soybean leaf siRNA and bisulfite sequencing

Here, we report an identical phenotype of super-early flowering dominance only in heterozygotes but not in homozygotes in soybean, and reveal the molecular mechanism of this new phenomenon. We found that the homozygous gene triggers siRNA-mediated DNA methylation, causing transcriptional gene silencing, while the heterozygous gene does not.

Interestingly, two rounds of DNA methylation establishment occur, each mediated by a distinct mechanism. The 21-22 nucleotide (nt) siRNAs are responsible for initiating DNA methylation in the CHH-context during the initial homozygosity of genes when the mother plants were heterozygous. In contrast, the 24 nt siRNAs play a role in the additional CHG- and CG-context DNA methylation during successive homozygosity of genes when the mother plants were already homozygous.