The Storage of the Extracted Plant DNA: Is –20°C Cold Enough?

Abstract

A high–quality DNA has crucial importance for enzymatic applications in plant molecular biology, including agricultural research. The researchers often need to store the extracted DNA, which has to be suitable for the downstream enzymatic applications, such as a real–time PCR, even after months and years. Storing the DNA as a precipitate in ethanol at –80°C is a commonly used method of preservation. The aim of this research was to determine whether the same was applicable to a temperature of –20°C. In this study, a high-quality DNA from soybean and maize seed was extracted by the widely used CTAB method. The DNA samples were stored at three regimes: water-diluted at +4°C, water-diluted at –20°C, and an undiluted DNA in ethanol at –20°C. The concentration and yield were measured using a spectrophotometer. The impurities and fragmentation were estimated on agarose gel by electrophoresis. Additionally, the DNA was assessed amplifying by the real–time PCR. The quantity and quality of the extracted DNA were assessed prior and subsequent to an annual storage. The results indicated that ethanol provided excellent protection for a short– term DNA storage at –20°C and probably for a long–term storage due to a reduced water content and slightly basic conditions. Thus, such a storage regime could be an appropriate solution when other options are not available.