An RNA isolation system for plant tissues rich in secondary metabolites

BACKGROUND: Secondary metabolites are reported to interfere with the isolation of RNA particularly with the recipes that use guanidinium-based salt. Such interference was observed in isolation of RNA with medicinal plants rheum (Rheum australe) and arnebia (Arnebia euchroma). A rapid and less cumbersome system for isolation of RNA was essential to facilitate any study related to gene expression. FINDINGS: An RNA isolation system free of guanidinium salt was developed that successfully isolated RNA from rheum and arnebia. The method took about 45 min and was successfully evaluated on twenty one tissues with varied secondary metabolites. The A(260/280 )ratio ranged between 1.8 - 2.0 with distinct 28 S and 18 S rRNA bands visible on a formaldehyde-agarose gel. CONCLUSIONS: The present manuscript describes a rapid protocol for isolation of RNA, which works well with all the tissues examined so far. The remarkable feature was the success in isolation of RNA with those tissues, wherein the most commonly used methods failed. Isolated RNA was amenable to downstream applications such as reverse transcription-polymerase chain reaction (RT-PCR), differential display (DD), suppression subtractive hybridization (SSH) library construction, and northern hybridization.