A simple and rapid method to detect plant siRNAs using nonradioactive probes

Small interfering RNAs (siRNAs) are key molecules in RNA silencing, which includes posttranscriptional gene silencing, cosuppression, quelling, and RNA interference. The presence of siRNAs indicates RNA silencing in cells. We present a method of detecting siRNAS using nonradioactive probes that involves isolating the small RNA fraction, separating siRNAs using denaturing gel electrophoresis, and performing a Northern blot analysis under low-stringency hybridization conditions. We used digoxigenin-labeled DNA probes for hybridization and detected siRNAs in petunia and rice plants exhibiting silenced phenotypes. This method is a simple and rapid way to detect siRNAs without using radioisotopes.