Identification of a Novel type of MT gene in rice and analysis on the molecular characteristics of its gene family | 水稻新型MT 基因的鉴定及其基因家族分子特征分析

chinois. ［目的］探讨水稻MT基因家族各成员在基因结构上的差异及相互间的进化关系。［方法］从经重金属处理的水稻幼苗中分离到3个新的植物MT，对其进行RT-PCR和Northern杂交分析以及水稻和拟南芥MT基因家族的序列比对和进化分析。［结果］RT-PCR和Northern杂交分析表明，水稻中3个MT基因的表达均受重金属的诱导，在幼苗根部进行特异性表达。由水稻和拟南芥MT基因家族的序列比对提出植物MT的新分类方式。水稻I类OsMT基因家族的所有10个成员，定位到6条染色体上。同一类型的OsMT有高度的氨基酸序列保守性，相似的Cys排列方式。新发现的3个OsMT家族在单子叶植物水稻中独有，属4型MT。［结论］水稻和拟南芥MT基因家族进化分析显示，植物MT至少发生在种子植物出现前，而4型MT可能发生于单子叶植物和双子叶植物分离后。_

anglais. ［Objective］This study aimed to explore the difference of each members of metallothionein (MT) gene family on gene construction and the evolution relationship among them each other. ［Method］3 novel plant MT genes in rice seedlings treated by heavy metal were isolated and they were made for RT-PCR and Northern blot analysis and the sequences alignment and evolution analysis of MT gene family between rice and Arabidopsis thaliana. ［Result］ RT-PCR and Northern blot analysis showed that in rice seedlings, the 3 MT genes were all induced by heavy metals and were dominantly expressed in roots. The new classification mode for plant MT was proposed on based of the sequences alignment of MT gene family between rice and A. thaliana. All 10 members of rice class I OsMT family were unevenly distributed in 6 chromosomes. The same type of OsMT showed a high conservation for amino acid sequence and the similar Cys-arrangement pattern. The novel 3 OsMT families were only particularly found in the monocotyledon of rice and were classified to type 4 of MT. ［Conclusion］ The evolution analysis on MT gene family of rice and A. Thaliana showed that the plant MT gene dated back at least to the origin of seed plants and type 4 of MT might originate after the monocotyledon-eudicot divergence.