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抗坏血酸过氧化物酶(APX)是一种在逆境条件下清除细胞内氧自由基、增强植物抗逆性的关键酶。本研究根据已发表植物抗坏血酸过氧化物酶基因APX的同源保守序列设计引物,采用RT-PCR扩增超强抗寒白菜型冬油菜陇油7号的DNA,获得APX基因开放阅读框,长度为753 bp,编码250个氨基酸残基,推导的氨基酸序列具有APX蛋白的典型特征。生物信息学分析显示,与已报道的大白菜的APX氨基酸序列同源性达99%,该酶蛋白具有高度的进化保守性,其保守序列属于植物的POD超家族,APX相对分子质量和理论等电点依次为27.7 kD和5.58;APX基因无信号肽,是一个亲水性蛋白,可推测其定位于细胞质中;二级结构预测表明陇油7号的APX是由不规则卷曲和α-螺旋组成的稳定蛋白。实时荧光定量PCR和酶活性分析显示,该基因表达和酶活性受低温胁迫诱导,表明该基因在白菜型冬油菜陇油7号适应低温胁迫过程中发挥重要作用。
Ascorbate peroxidase (APX) is a key enzyme that scavenges intracellular oxygen free radicals and enhances plant stress resistance under adverse conditions. In this study, primers were designed based on homologous conserved sequences of published plant ascorbate peroxidase (APX) gene APX, and RT-PCR was used to amplify the DNA of the super cold resistant Chinese cabbage Longyou Longyou No.7. The APX gene open reading frame Was 753 bp, encoding a polypeptide of 250 amino acids. The deduced amino acid sequence has the typical characteristics of APX protein. Bioinformatics analysis showed that the APX amino acid sequence homology with reported Chinese cabbage 99%, the protein has a high degree of evolutionary conservation, the conserved sequence belongs to the plant POD superfamily, APX relative molecular mass and theory The APX gene has no signal peptide and is a hydrophilic protein, which can be presumed to be located in the cytoplasm. The secondary structure prediction shows that APX is composed of irregular curly and α-helix Composition of stable protein. Real-time quantitative PCR and enzyme activity analysis showed that the gene expression and enzyme activity were induced by low temperature stress, indicating that the gene plays an important role in adaptation to low temperature stress in Chinese cabbage type Longyou Longyou 7.