大蒜扩展蛋白基因AsEXPA8的分离及其参与渗透胁迫响应的分析

Isolation of Garlic Expansin Gene AsEXPA8 and Its Involvement in Osmotic Stress Response

扩展蛋白在植物生长发育和应对环境变化等过程中发挥重要作用。为了解大蒜扩展蛋白基因的序列特征及其在渗透胁迫下的功能,利用逆转录PCR(RT-PCR)方法从大蒜中克隆得到AsEXPA8基因,采用NCBI、ExPASy、SignalP 5.0和STRING等网站以及DNAMAN和MEGA 5.1软件对其序列进行分析,并采用实时荧光定量PCR技术对AsEXPA8基因在盐胁迫和模拟干旱胁迫下的表达特征进行研究。序列分析结果表明,AsEXPA8含有1个774 bp的开放阅读框,编码257个氨基酸。AsEXPA8蛋白有1个组氨酸-苯丙氨酸-天冬氨酸(His-Phe-Asp,HFD)基序,N端和C端分别含有8个保守的半胱氨酸残基和4个保守的色氨酸残基,具有信号肽和跨膜结构域,参与了生长素和赤霉素等激素调控细胞壁重构的过程。AsEXPA8在大蒜不同组织中均能表达,在叶片中表达相对较高。干旱胁迫和盐胁迫在不同组织内均诱导了AsEXPA8的表达。结果表明,AsEXPA8基因可能参与了大蒜植株抵御盐胁迫和干旱胁迫的过程。本研究结果为揭示AsEXPA8基因在大蒜应对渗透胁迫过程中的功能提供了理论依据。

Expansin plays an important role in plant growth and development and is involved in the response to environmental changes.In order to understand the sequence characteristics of garlic expansin gene and its function under osmotic stress,AsEXPA8 gene was cloned from garlic by reverse transcription-PCR(RT-PCR).NCBI,ExPASy,SignalP 5.0,and STRING websites as well as DNAMAN and MEGA 5.1 software were adopted to analyze its sequences.Its expression profiles under salt stress and simulated drought stress were determined by quantitative real-time quantitative PCR.Sequence analysis showed that AsEXPA8 contained a 774 bp open reading frame encoding 257 amino acids.The AsEXPA8 protein has a histidine-phenylalanine-aspartate(His-Phe-Asp,HFD)motif.The N-terminal and C-terminal contain 8 conserved cysteine residues and 4 conserved tryptophan residues,respectively.It has signal peptide and transmembrane domain,and may be involved in the process of cell wall remodeling regulated by hormones such as auxin and gibberellin.AsEXPA8 can be expressed in different tissues of garlic,and the expression is relatively high in the leaves.Drought stress and salt stress induced the expression of AsEXPA8 in different tissues.Therefore,it can be speculated that AsEXPA8 gene may be involved in the resistance against salt stress and drought stress in garlic plants.The results of this study provide a theoretical basis for revealing the function of AsEXPA8 gene in garlic response to osmotic stress.