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.