An Improved Protocol for Isolation of high-quality RNA from potato ( Solanum tuberosum L. ) and other underground storage tissues

RNA isolation is an important step in any transcriptome-based functional genomics study, and the quality and quantity of RNA are crucial for downstream applications like gene expression. Since plant cells contain diverse metabolites, such as polyphenols, starch, etc., isolation of pure-quality RNA is always a challenging task. Specialized plant tissues, such as underground storage organs of potato, turnip, beet, carrot, and other crops, are extremely rich in starch and other secondary metabolites. RNA isolation from these tissues with commonly used reagents (e.g., Trizol) or commercial kits often results in inferior quality and quantity of RNA unsuitable for downstream applications. In the present study, a modified CTAB and SDS-based homogenization procedure amalgamated with the routinely used phase separation procedure has been employed for RNA isolation. High-quality RNA from multiple tissues, especially plant underground storage organs, was obtained with an absorption (A 260 /A 280 and A 260 /A 230 ) value of 1.80–2.00 and ~ 2.00, respectively. In order to evaluate the suitability of isolated RNA in downstream applications, first-strand cDNA was synthesized and used to amplify seven genes considered as the standard reference genes for different plant storage tissues. RNA isolation from cold-stored potato tuber and gene expression studies also demonstrated suitability and wide applicability of this protocol. Overall, the results indicated better efficacy of the protocol employed in the present study than the existing resource-demanding RNA isolation methods available for potato and other secondary metabolite-rich plant storage organs.