An efficient protocol for genomic DNA extraction from<Emphasis Type="Italic">Citrus</Emphasis> species

We describe a simple and efficient method for genomic DNA extraction from woody fruit crops containing high polysaccharide levels. This method involves a modified CTAB or SDS procedure employing a purification step to remove polysaccharides by using water-saturated ether and 1.25 M NaCl. Precipitation with an equal volume of isopropanol caused a DNA pellet to form. After being washed with 70% ethyl alcohol, the pellet easily dissolved in TE buffer. Using this method, DNA was extracted from samples of more than 1000Citrus spp., including young leaves, old leaves, frosted old leaves, withered old leaves, and callus lines. The average yield of DNA ranged from 50–500 μg/g of sample. DNA was suitable for PCR and RFLP analyses and long-term storage. Recently, the procedure was used to isolate DNA from withered old leaves of more than 20 tropical and subtropical fruit crops.