核基质结合区(matrix attachment region, MAR)的应用是提高植物基因转化和表达效率的有效方法之一。将烟草(Nicotiana tabacum)核基质结合区TM2构建在植物表达载体pBI121上报告基因GUSA表达盒和选择标记基因NPTII表达盒的两侧翼, 利用农杆菌介导的子叶浸染转化番茄(Lycopersicon esculentum)。结果表明, MAR序列能够显著提高转基因植株的转化效率和转基因的表达水平。不同长度的CaMV 35S启动子比较表明, TM2的调控活性依赖于启动子的存在, 并且具有一定的功能重叠。热诱导型启动子的研究表明, TM2仅提高热诱导的表达强度, 而不改变启动子的热诱导表达调控特性。TM2的表达调控特性符合转基因的表达要求, 该MAR序列可广泛应用于各种植物的基因工程中。
Use of matrix attachment regions (MARs) is an important method to improve gene transformation and transgenic expression in plants. We constructed the TM2 MAR from tobacco at the flanking sides of the expression cassettes of reporter gene GUSA and selective gene NPTII in a plant expression vector, pBI121. The recombinant constructs were introduced into tomato plants by Agrobacterium-mediated cotyledon transformation. The transgenes were increasingly transformed and expressed in the transformants. Comparison of the effect of TM2 on different lengths of CaMV 35S promoter showed that the transcription enhancement of TM2 depended on the existence of promoter and showed partial functional redundancy. The effect of TM2 on transcription regulated by heat-inducible promoter indicated that the MAR did not change the regulation pattern but improved the expression level of the heat-inducible promoter. These characteristics of TM2 MAR fulfill the regulation requirements for transgenic expression and can be widely used in diverse plant biotechnology.
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