中文摘要：

对于苜蓿中华根瘤菌转化方法的研究仅限于三亲杂交法和电激转化，本实验首次将冻融法用于转化苜蓿中华根瘤菌。将携带CUS片段并且含有壮观霉素抗性的质粒用冻融法转移至野生型苜蓿中华根瘤菌菌株，得到的抗性克隆用GUS引物进行PCR扩增鉴定。经过计算，冻融法的转化率为2．2×10^5／μg。与传统方法比较，冻融法操作简单，转化过程快速，转化率较高，所需时间较短，转化成本低，是适合用于苜蓿中华根瘤菌的转化方法。

英文摘要：

The transformation for Sinorhizobium meliloti 1021 was limited to triparental-conjugational and electric-shock methods. Plasmid containing GUS and spectinomycin-resistance gene was used in our experiment. After transformation, resistant clones on the plate were identified by PCR with GUS primers. This report firstly described a freeze-thaw mediated transformation of S. meliloti 1021. The result showed that the transformation efficiency was 2, 2 10^5/g. Compared with the traditional methods, the freeze-thaw mediated transformation is a simple, faster, shorter time and lower cost method to transform Sinorhizobium meliloti.