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采用RT-PCR和RACE方法从菠萝克隆获得一个MADS-box基因,命名为Ac MADS2,Gen Bank登录号为KC257409。AcMADS2基因c DNA全长945 bp,ORF为687 bp,编码一个含有228个氨基酸的蛋白。序列分析和系统进化分析表明,AcMADS2具有保守的MADS-box结构域和半保守的K区,与其他植物中的AGL12亚家族MADS-box蛋白具有很高的同源性。生物信息学分析结果表明,Ac MADS2是不稳定的亲水蛋白,不具有跨膜结构和信号肽。α-螺旋、折叠延伸链及无规则卷曲构成了二级结构的主要蛋白框架。在三级结构中MADS-box结构域构成了该蛋白核心结构,并且作为转录因子可能定位于细胞核。实时荧光定量PCR分析表明,Ac MADS2基因在花期根中的表达量明显高于同一时期的小花、茎和叶;干旱和低温胁迫处理后,Ac MADS2基因在苗期根中的表达也明显增强。因此,推测Ac MADS2基因可能参与菠萝根发育的调控以及逆境胁迫反应。
A MADS-box gene was cloned from pineapple by RT-PCR and RACE, named Ac MADS2, Gen Bank Accession No. KC257409. The cDNA of AcMADS2 gene was 945 bp in length with ORF of 687 bp and encoded a protein of 228 amino acids. Sequence analysis and phylogenetic analysis showed that AcMADS2 has a conserved MADS-box domain and a semi-conserved K region, which has high homology with the AGL12 subfamily MADS-box protein in other plants. Bioinformatics analysis showed that Ac MADS2 is an unstable hydrophilic protein with no transmembrane structure and signal peptide. The a-helices, folded extension chains and irregular curls constitute the secondary protein framework of secondary structure. In the tertiary structure, the MADS-box domain forms the core of this protein, and may act as a transcription factor in the nucleus. Real-time quantitative PCR analysis showed that the expression level of Ac MADS2 gene in flowering roots was significantly higher than that in the same period of flowers, stems and leaves. Ac MADS2 gene expression in roots was significantly increased after drought and cold stress. Therefore, it is speculated that Ac MADS2 gene may be involved in the regulation of pineapple root development and stress response.