Simple, rapid and reliable methods to obtain high quality RNA and genomic DNA from Quercus ilex L. leaves suitable for molecular biology studies

Isolation of high-quality RNA and genomic DNA (gDNA) from many samples is a necessary step before accomplishing molecular biology studies. The particular composition of Quercus ilex leaves, specially hard and rich in cell wall material, polyphenolics and secondary metabolites, usually results in preparations contaminated with non-nucleic acid compounds. Although many methods have been developed, each case of study demands a protocol adapted to the specific plant sample and the pursued research objectives. We have evaluated several protocols to establish the methodology that best suited to our current genetic and molecular studies on Q. ilex. Our priority was to select the simplest methods reducing the plant starting material and the time employed, without compromising yield, quality and integrity of the isolated nucleic acids. Our results point to two protocols based on silica-membrane purification, as the most convenient for Q. ilex leaf tissue, and both procedures are greatly improved by adding insoluble polyvinyl polypyrrolidone during the isolation process. The protocols optimized here can be completed at the microfuge scale and allow a researcher to process 48 samples in 1 h, producing high quality preparations suitable for the routinely molecular biology applications with higher efficiency than other more labour and time-consuming protocols.