三叶木通光敏色素A基因的序列及表达分析

光敏色素( phytochrome,简称PHY)是植物体内最重要的光受体,参与调节植物种子萌发、幼苗生长、茎的伸长、子叶伸展直至开花控制等许多生理过程。该研究通过RT-PCR方法首次从三叶木通( Akebia trifoli-ata)中获得了编码光敏色素A的cDNA序列(命名为AktrPHYA1,GenBank登录号为KP864055)。结果表明：该序列由3496 bp组成,包含一个3426 bp的完整开放阅读框,编码1141个氨基酸。 AktrPHYA1编码的蛋白N端为光感受区域,包括一个GAF结构域、一个PHY结构域；C端为光调节区域,C端包括两个PAS结构域、一个组氨酸激酶A结构域和一个类似组氨酸激酶的ATP 激酶结构。同源蛋白比对显示,AktrPHYA1与耧斗菜、荷花的同源蛋白序列一致性分别为83％和82％。遗传进化树分析表明,单子叶植物和双子叶植物的光敏色素A基因分别聚为两支；在双子叶植物中,AktrPHYA1与耧斗菜、荷花PHYA聚在一起,说明三叶木通与耧斗菜、荷花遗传关系较近。 AktrPHYA1在三叶木通茎、叶片、雄花、雌花、种子中均有表达,且在种子中表达最强,在叶片中表达量最低。 AktrPHYA1的组织表达谱暗示了其在植物中可能的功能。该研究结果为三叶木通光敏色素A基因的功能研究奠定了基础。

Sequence and expression analysis of phytochrome A from Akebia trifoliata

Phytochrome(PHY)is one of the most important light receptors in plants. It is involved in many physiological processes such as the regulation of seed germination, seedling growth, stem elongation, cotyledon extension, and flowering control. In this study, a cDNA encoding PHYA was firstly amplified from Akebia trifoliata by using the RT-PCR technique(designated as AktrPHYA1, GenBank accession number: KP864055), which consists of 3 496 bp, with a 3 426-bp open reading frame(ORF)encoding a 1 141-amino-acid protein. The N-terminal of AktrPHYA1 is dedicates for light acceptation and contains a GAF domain and a phytochrome domain. The C-terminal is a light-regulated region, and is comprised of two PAS domains, a His Kinase A domain and a Histidine kinase-like ATPase domain. The homology protein alignment showed that the AktrPHYA1 shared 83% and 82% identities with the PHYAs from Nelumbo nucifera and Aquileqia formosa, respectively. Phylogenetic tree analysis indicated that monocots and dicots gathered into two branches. In the dicots, Akebia trifoliate, Nelumbo nucifera and Aquileqia formosa clustered together, indicating they are closely genetically related. Expression analysis indicated that AktrPHYA1 was detected in all tissues under investigation, including leaves, stems, male and female flowers and seeds. It was the most strongly expressed in seeds, whereas the most weakly in leaves. The expression pattern implied the likely roles of AktrPHYA1 in Akebia trifoliata. This work will provide information for further research of its functions in plants.