**6. References**


The suitability of extracted DNA for downstream molecular processes was further verified by molecular markers ISSR-PCR amplification. AS shown in Fig. 4, the genomic DNA of five different *R. soongorica* populations were highly amplifiable by ISSR-PCR as indicated by the amplification products resolved on 1.5% agarose gel. This further confirmed the purity of DNA, free of polysaccharide and polyphenol contamination, which would otherwise inhibit Taq DNA polymerase and restriction endonucleases (Ahmad et al., 2004). Plant molecular applications such as RAPD and AFLP necessitate the successful isolation of high quality DNA (Michiels et al., 2003; Ahmad et al., 2004), devoid of contaminants. Without high quality DNA such downstream molecular manipulations are not feasible (Varma et al., 2007). To confirm the applicability of our method, this DNA extraction method has also been found to be efficient in other desert plants, including *Tamarix ramosissima*, *Nitraria* 

Our results showed that the modified CTAB-B method promoted here was of high quality, purity and yield and was suitable for downstream molecular assays. Based on a CTAB method, the protocol has been improved as follows: the more volume of extraction buffer was used to completely break down the cell walls; the samples were ground with PVPP to effectively inhibit the oxidation of phenolics; during the extraction, 3 mol/L sodium acetate (NaAc) was added to reduce markedly the co-precipitation of polysaccharides with the nucleic acids; contaminating RNA was removed with RNase I; acid phenol extraction (phenol: chloroform: isoamylal alcohol (PCI)=25:24:1) was used to effectively removes the residual proteins and inhibitors in the RNase reagent. Thus, despite the high levels of secondary metabolites in the leaves of *R soongorica*, the high quality DNA is isolated from the nuclei without interference. Moreover, the new protocol is also suitable for isolating genomic DNAs

This study was supported by the National Key Technologies R&D Program: The Integration and Experiment Demonstration of Ecological Restoration Technology in Loess Hills-Sand Areas (2011BAC07B05) and by the Ministry of Forestry Commonweal Special Project: Monitoring and Assessment Technologies for Hydrological Regulation Function of Desert

Ahmad S.M., Ganaie M.M., Qazi P.H., Verma V., Basir S.F., Qazi G.N. 2004. Rapid DNA isolation protocol for angiospermic plants. Bulgarian Journal of Plant Physiology 30, 25–33. Bai J., Xu D.H., Kang H.M., Chen K., Wang G. 2008. Photoprotective function of

Barnell P., Blanchard A.N., Bryant J.A., Smirnoff N., Weir A.F. 1998. Isolation of DNA from

natural high irradiance. Photosynthetica 46, 232–237.

photorespiration in *Reaumuria soongorica* during different levels of drought stress in

the highly mucilaginous succulent plant *Sedum telephium*. Plant Molecular Biology

from other desert plant species and tissues that are rich in secondary metabolites.

*tangutorum* and *Caragana korshinskii* Kom. (data not shown).

**4. Conclusion** 

**5. Acknowledgments** 

Ecosystem (201004010-05).

Reporter 16, 133–138.

**6. References** 

