Isolation of functional RNA from cactus fruit

Isolating RNA from cactus fruit is notoriously difficult because the fruit contains high amounts of secondary metabolites and polysaccharides. These form insoluble complexes with nucleic acids during extraction and can inhibit enzyme action. Our procedure allows for the extraction of RNA from finely ground tissue. The RNA we isolated was of high quality and undegraded, as gauged by spectrophotometry and electrophoresis in agarose gels. Quality was further assessed through use of the RNA in RT-PCR and northern blot analysis, indicating that it could be used to construct cDNA libraries. Using this modified protocol, 90 mug of RNA was routinely obtained from I g of dried cactus fruit. Isolating RNA from other polysaccharide-rich fruits was also possible.