The system uses some reagents quickly permeating the biological samples and simplifies total RNA isolation by combination of the stringency of guanidine-thiocyanate lysis and silica-gel-membrane purification. This system has no need for phenol/ chloroform extraction and centrifugation with CsCl gradients or precipitation with LiCl or ethanol. Plant tissues that contain sticky secondary metabolites are lysed by additional provided PRX Buffer.