An improved method for isolating polyphenol-free RNA from woody plant tissues

We describe an efficient and reliable technique for isolation of total RNA from woody plant tissues. Because of the high levels of phenolic compounds in tissues such as stem, dormant buds and underlying bud tissues, RNA canno t be extracted as uncomplexed intact molecules by standard methods. The key principle for eliminating phenolic compounds was the combined use of polyv inylpolypyrrolidone and a solvent, 2-butoxyethanol. Furthermore, this modif ied procedure allowed the extraction of RNA from small amounts of woody tis sues with high efficiency. The isolated RNA was suitable for hybridization, cDNA cloning and reverse transcriptase-polymerase chain reaction. This pro tocol has been applied with success to woody plants like peach and walnut.