摘  要：玉米是重要的粮、经、饲兼用作物，同时还是制药、淀粉糖浆、油料、酒精工业的主要原料，在世界及我国的经济生活中具有非常重要的地位和作用。然而，随着植物科学向分子水平的深入发展，玉米选种、育种、改良和鉴定等研究中经常需要获得有效的植物DNA样品。玉米是一年生禾本科植物，它的叶片中富含大量的多糖、多酚等代谢产物，使提取DNA较困难。本实验以不同叶龄玉米叶片为材料，采用CTAB和SDS方法通过对玉米幼芽、幼嫩叶、成熟叶提取DNA，采用紫外-可见分光光度计和琼脂糖凝胶电泳检测DNA的纯度，从而分析不同叶龄玉米叶片对DNA提取质量的影响。结果表明不同叶龄的玉米叶片对DNA的质量、产率有较大影响，幼芽和幼嫩叶片的DNA产率高，质量好，随叶片生长，DNA的产率不断下降。成熟叶片中含有较多的初次生代谢产物如酚类、多糖类、脂类等物质，而且所含DNA相对较少，所以提取难度大，纯度低。以幼芽、幼嫩叶为最适的提取材料。
    关键词：玉米；DNA提取；DNA纯度
 
Different Age Maize Leaves Impact on The Quality of DNA Extraction And Optimization
    Abstract：Corn is an important grain, classics, and forage crops, or pharmaceuticals, starch syrup, oil, the main raw material of the ethanol industry in the world and It has a very important position and role in the world and our country's economic life. However, with the plant science to the in-depth development of molecular level, corn seed selection, breeding, improvement and identification studies often need access to effective plant DNA samples. Corn is an annual grass plant, its leaves are rich in polysaccharides, polyphenols and other metabolites, DNA was extracted more difficult. In this experiment, different ages maize leaves using CTAB and SDS by corn shoots, young leaves, mature leaf extract DNA by UV - visible spectrophotometer and agarose gel electrophoresis purity of the DNA, thus different ages maize leaves on the quality of DNA extraction. The results showed that different leaf stage of corn leaves have a greater impact on DNA quality, yield, shoots and young leaves of DNA yield, good quality, with the growth of leaves, the yield of DNA declining. Mature leaves contain more initial metabolites, such as phenols, polysaccharides, lipids and other substances, and the DNA contained in a relatively small, so it is difficult to extract a low purity. The optimum bud, and young leaf are the extract materials.
Key words：Corn; DNA extraction; DNA purity，
目录

摘要1
引言2
1．DNA提取研究进展2
1.1DNA提取的基本原理2
 1.2DNA提取常用的方法3
  1.2.1  CTAB法3
  1.2.2 SDS法3
 1.3细胞的破碎3
 1.4核酸和蛋白质复合物的分离3
 1.5去除多糖常用的方法4
 1.6去除多酚常用的方法4
 1.7去除RNA4
2．材料和方法4
 2.1材料4
 2.2仪器4
 2.3试剂4
  2.3.1提取试剂4
2.3.2紫外可见分光光度计分析试剂4
2.3.3凝胶琼脂电泳所用试剂4
 2.4材料处理5
 2.5 DNA提取方法5
2.5.1  CTAB法提去DNA 5
2.5.2 SDS法（十二烷基苯磺酸钠法）提取DNA 5
 2.6指标测定方法6
2.6.1紫外可见分光光度计检测6
 
2.6.2琼脂糖凝胶电泳检测6
3.结果与分析6
 3.1不同方法提取玉米不同叶龄叶片的DNA的紫外吸光值比较6
 3.2 不同方法提取玉米不同叶龄叶片的DNA的凝胶琼脂糖电泳结果比较7
4.结论与讨论7
参考文献8 不同叶龄玉米叶片对DNA质量的影响和条件优化:http://www.youerw.com/shengwu/lunwen_26.html