Contents of eight saccharides in unprocessed and processed Rehmannia glutinosa and content changes at different processing time points HPLC chromatogram changes with processing for roots of Radix Rehmanniae Effect of stachyose on microbiotic disequilibrium in rhizospheric soil of Rehmannia glutinosa Cloning and Expression Analysis of Stachyose Synthase Gene in Brassica napus L. Advance in Raffinose Family Oligosaccharides Metabolism and the Key Enzymes in Plants