I am currently trying (again and again.....) to extract RNA from woody samples
(Cornus sericea L.). I sterilize all the my equipment, use autoclaved and DEPC-
treated water, buffers and solutions and wear gloves during the extraction
procedure. The extraction buffer contains 4 M guanidine thiocyanate and I use a
cesium chloride gradient followed by phenol/chloroform extraction and ethanol
precipitation (as described by Clausen and Apel . Plant Mol. Biol. 17(4):
669-678) for the isolation of RNA from the xylem of poplar trees).
The purity of the RNA (E260/E280) is 2.0, but no matter whether I use fresh or
freeze dried material: the RNA is always completely degraded.
Any help on this matter would be greatly appreciated.
Thanks in advance