Development of modified CTAB and Trizol protocols to isolate high molecular weight (HMW) RNA from polyphenol and polysaccharides rich pigeonpea (Cajanuscajan (L.) Millsp.

Pigeonpea (Cajanuscajan L.) is a legume crop that contains high levels of polyphenolic compounds and polysaccharides that become a hindrance in extracting good-quality and enough amount of RNA from its tissues. With the existing methods of RNA isolation, the phenolic compounds may co-precipitate or bind to the RNA giving false results. Therefore, in the present study, we have modified conventional CTAB and Trizol-based methods which resulted in good quality with the absorbance A260/A280 ratios in the range of 1.83 to 1.98 and A260/230 ratios in the range of 2.0-2.23, revealed RNA to be of high purity and free of contaminants. Both of the proposed protocols yielded a good quantity of RNA ranging from 289 to 422μg per gram of tissue. Distinctly visible bands of 28S and 18S rRNA were observed without degradation or smear, which indicated the presence of intact RNA. RT-PCR analysis showed that isolated RNA was quantitatively sufficient and compliant for the subsequent gene expression analysis.