菜薹BcAMT1;4启动子的克隆及活性分析

以菜薹（Brassica campestris L. ssp. chinensis var. utilis Tsen et Lee）为材料，利用染色体步移法获得了铵转运蛋白基因BcAMT1;4的ATG上游长度为2 086 bp的启动子序列。生物信息分析表明，该启动子中包含多个光信号、激素信号、逆境应答、组织特异表达等顺式作用元件。构建该启动子与GUS基因的融合表达载体，并用农杆菌介导法转化拟南芥。通过对T3代转基因拟南芥植株GUS活性分析发现，GUS染色主要集中于叶片，而在根、茎、花中染色较浅。此外，不同氮源也影响BcAMT1;4启动子的活性，缺氮处理提高了转基因拟南芥GUS表达活性，而分别供0.25 mmol ? L-1 NO3-、NH4+和NH4NO3的处理在一定程度上抑制其表达活性。研究结果表明，BcAMT1;4可能对菜薹叶片铵态氮营养具有重要调控作用。

Cloning and Functional Analysis of BcAMT1;4 Gene Promoter in Flowering Chinese Cabbage

In the present study，ammonium transporter gene BcAMT1;4 promoter sequence with upstream length of 2 086 bp for ATG was obtained from flowering Chinese cabbage（Brassica campestris L. ssp. chinensis var. utilis Tsen et Lee）using genomic walking. Bioinformatics analysis indicated that the promoter contains multiple cis-acting elements associated with light signals，hormone signals，stress response，and tissue-specific expression. To further analyze the promoter function of BcAMT1;4，a recombinant vector of BcAMT1;4 promoter and GUS was constructed and transformed into Arabidopsis by Agrobacterium tumefaciens. Analysis of T3 transgenic Arabidopsis tissues with GUS staining showed that GUS was mainly expressed in leaf，while expressed slightly in root，stem，and flower. Also，the activity of BcAMT1;4 promoter was affected by nitrogen source forms in Arabidopsis. Nitrogen starvation induced the GUS activity in transgenic Arabidopsis，however，the GUS activity was inhibited by 0.25 mmol ? L-1 NO3-，NH4+，or NH4NO3 treatment. In conclusion，the results showed that BcAMT1;4 might play an important role in regulating ammonium nutrient in leaf of flowering Chinese cabbage.