K^+通道基因MIRK在网纹甜瓜植株中的表达分析

Expression of K^+ Channel Gene MIRK in Muskmelon

在网纹甜瓜(Cucumis melovar.reticulatus Naud.)叶片中克隆了一个cDNA片段,片段长1 330 bp。这段cDNA序列及由此推测的氨基酸序列分析和多序列比对表明扩增的片段是编码K+通道MIRK(Melon Inward Rectifying K+Channel)基因的5′端。由此cDNA片段推测的氨基酸序列包含了6个跨膜片段S1到S6,其间有一个对离子选择性有重要作用的特征序列结构GYGD(Gly-Tyr-Gly-Asp)。进化树分析显示MIRK属于KAT1亚家族,和在葡萄叶片中克隆的K+通道SIRK最相近。半定量RT-PCR试验表明,MIRK在甜瓜植株中根、茎、叶、花、果实等各器官中均有表达,主要在叶片和初期发育的果实中表达,在雌花和茎中也有表达,在根中的表达量最低。MIRK在甜瓜不同器官中的表达模式显示MIRK可能在甜瓜植株发育过程中起重要作用。

A 1 330 bp cDNA fragment of K^＋ channel gene MIRK（Melon Inward Rectifying K^＋ Channel）was isolated from leaves of muskmelon（ Cucumis melo var. reticulatus Naud. ）. The nucleotide sequence and its deduced amino acid sequence analysis displayed that the cDNA fragment was located in the 5＇-terminal of MIRK gene and contained six trans- membrane segments S1 - S6 and a GYGD（Gly-Tyr-Gly-Asp） motif. Phylogenetic analysis showed that MIRK was belonged to the KAT1 sub-family and most close to the SIRK of Vitis vinifera. The results of semi-quantitive RT-PCR displayed that MIRK was preferentially expressed in leaves and fruits, and also expressed in female flowers and shoots, but nearly not expressed in roots, indicating that MIRK might play a key role in the muskmelon development.