Wilcockson利用蛋白质与RNA在高氯酸钠溶液中的溶解度不同将它们分离。在70％高氯酸钠溶液中，RNA的溶解度大于蛋白质的溶解度，因而将大部分蛋白质沉淀下来。接着在离心上清液中加入两倍体积的无水乙醇，这时RNA能沉淀下来而能溶于70％高氯酸钠溶液中的残留蛋白质仍然留在上清液中。这样可以除去绝大部分的蛋白质［17］。
4 次级代谢产物的影响及对策
从植物组织中提取高质量RNA的另一个难点是许多高等植物组织尤其是成熟组织能产生某些水溶性的次级代谢产物，这些次级代谢产物很容易与RNA结合并与RNA共同被抽提出来而阻碍具有生物活性的RNA的分离。因不能确定这些次级产物具体是什么物质，所以，目前还没有什么特殊的方法来解决这个问题。Baker等［18］综合Hughes等［16］的选择性沉淀法、Chirgwin［19］的氯化铯梯度离心法和Iversen等［20］的RNA回收方法纯化了松树种子、成熟松树针叶等植物组织的RNA。
由于植物组织特别是高等植物组织细胞内外组成成分的复杂多样性，使得植物组织RNA的提取相对于其它生物材料来说要困难的多。实践中经常会发现，即使同一种植物的不同组织其RNA提取方法会有很大的不同［13］；含有某种干扰因素的不同植物材料，其适用的RNA提取方法可能不同；即使是同一种植物同一种组织材料，但来源于不同基因型植株，其RNA提取方法也可能不一样［7］。所以，对于某一植物或其组织来说，其相应的RNA提取方法必需经过摸索和实践才能确立。
随着植物分子生物学研究领域的拓宽，可以肯定地说，在作为其研究基础的植物材料RNA提取过程中还会出现新的难点，但随着不断地探索和经验的积累，科学工作者们一定会迅速地解决这些难点，为植物分子生物学的发展铺平道路。
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