Abstract: Arginine decarboxylase (ADC) is a key enzyme involved in polyamine biosynthesis in plants. To explore the sequence characteristics of ADC gene from pear and its response to abiotic stress PbADC gene was cloned from Pyrus betulifolia by RT-PCR. Sequence analysis of PbADC was carried out by bioinformatics software, and real time quantitative PCR was utilized to detect the expression level of PbADC in different tissues and its response patterns to various abiotic stresses. The results showed that the open reading frame of PbADC was 2 190 bp in length, encoding 730 amino acids and there were 66 phosphorylation sites in the predicted protein. Domain analysis showed that PbADC contained a conserved 2-pyridoxal phosphate binding site, a PLP phosphate binding site and a substrate recognition signal domain, which belongs to the type Ⅲ PLP-dependent arginine decarboxylase protein family. Moreover, PbADC was close to apple MdADC, sweet cherry PaADC and peach PpADC in genetic relationship. The results of qRT-PCR demonstrated that the expression of PbADC in leaves was higher than that in roots and stems, and the transcript levels of PbADC were regulated by low temperature, dehydration, salt and hydrogen peroxide. The results of this study will provide a theoretical basis for further exploration of the function in abiotic stress of PbADC.

Key words: Pyrus betulifolia, PbADC gene, gene cloning, abiotic stress, expression analysis

摘要： 精氨酸脱羧酶(ADC)是植物多胺生物合成途径中的关键酶。为探索ADC基因在杜梨中的序列特征及其对非生物胁迫的应答特性,采用反转录PCR(RT-PCR)技术从杜梨中克隆PbADC基因,利用生物信息学软件进行序列分析,并通过荧光定量PCR技术检测其在不同组织中的表达水平和对多种非生物胁迫的响应。结果表明,PbADC基因的开放阅读框全长2 190 bp,编码730个氨基酸,预测PbADC蛋白含有66个磷酸化位点。结构域分析显示,PbADC含有保守的2-磷酸吡哆醛结合位点、磷酸吡哆醛(PLP)磷酸基结合位点和底物识别信号序列,是Ⅲ型磷酸吡哆醛依赖性精氨酸脱羧酶家族成员。在亲缘关系上与苹果MdADC、甜樱桃PaADC和桃PpADC较为接近。荧光定量PCR检测结果表明,PbADC在叶片中的表达量高于根和茎部组织,且该基因的转录水平受低温、脱水、盐和过氧化氢等非生物胁迫调控。本研究结果为进一步探讨PbADC基因的抗逆功能提供了理论依据。

关键词: 杜梨, PbADC基因, 基因克隆, 非生物胁迫, 表达分析