白桦BpHO基因非生物胁迫及信号诱导的表达模式分析

Analysis of the expression patterns of BpHO gene induced by abiotic stress and signal in birch

血红素加氧酶(heme oxygenase,HO)是一种普遍存在的敏感的和高活性的血红素分解代谢过程中的限速酶。本文揭示了白桦Bp HO在非生物胁迫及信号诱导调控的表达特征,为该基因在白桦中代谢调控功能的研究奠定基础。通过前期研究获得了白桦HO基因,命名为Bp HO,应用生物信息学软件分析了白桦Bp HO基因的分子结构特征,利用重金属镉(Cd)、盐(Na Cl)以及4℃低温进行非生物胁迫处理,利用硝普钠(SNP)和水杨酸(SA)进行信号诱导,分析Bp HO的表达特征。生物信息学分析表明该基因全长855 bp,含有完整的开放读码框,编码284个氨基酸(Genebank登录号:KJ197335)。Bp HO为不稳定类疏水性蛋白,不存在信号肽,也不具有跨膜能力,α-螺旋、延伸链、无规则卷曲分布于整个蛋白。分子进化分析结果表明,白桦Bp HO基因与葡萄的遗传距离较近,说明二者亲缘关系较近;与大豆、菜豆、豌豆的遗传距离较远,说明其亲缘关系较远。非生物胁迫结果表明,Bp HO基因的表达水平随非生物胁迫处理时间的不同而上下波动,但在处理6 h后Bp HO基因对4种非生物胁迫处理都上调表达,说明Bp HO基因对非生物胁迫具有响应。信号诱导结果表明,外源NO调节了Bp HO基因的转录表达,调控血红素加氧酶的合成。SA也参与了Bp HO基因的信号调控。盐、低温、重金属镉胁迫均能促进Bp HO的表达,但响应模式不同。

Heme oxygenase（ HO） is the rate-limiting enzyme in the process of heme catabolism which is ubiquitous,sensitive,and highly active. This paper reveals the Bp HO expression pattern in signal induction and regulation of secondary metabolism,in an attempt to lay the foundation for the study of gene function in metabolic regulation of birch. In our previous research,the HO gene has been cloned from birch（ Betula platyphylla）,named Bp HO. The molecular structure of Bp HO was analyzed by bioinformatics software. Abiotic stress by cadmium（ Cd）,salt（ Na Cl） and low temperature（ 4 ℃）,and signal induced by sodium nitroprusside（ SNP） and salicylic acid（ SA） were used in the study. The expression patterns of Bp HO induced by abiotic and signal induction were analyzed. Bioinformatics analysis showed that Bp HO is 855 bp,and contains the complete ORF,encoding 284 amino acids（ Genebank ID： KJ197335）. Bp HO is an unstable hydrophobic protein,which does not possess signal peptide and the transmembrane ability either. The alpha helix,extension chain and random coil are distributed throughout the protein. Molecular evolution analysis results showed that the genetic distance of Bp HO gene between birch and grape species is relatively close. The gene heredity distance is farther with soybean,Kidney bean and pea,explaining the far genetic relationship with them. Abiotic stress results indicated that Bp HO gene expression levels varied with abiotic stress time with fluctuations,but after 6 htreatment Bp HO gene for four abiotic stress treatments were up-regulated,indicating Bp HO genes are responsive to abiotic stresses. The results suggest that the signal induced by exogenous NO regulates transcription expression of Bp HO and the synthesis of heme oxygenase. Salicylic acid is also involved in expression of Bp HO. Salt,low temperature,heavy metal,and cadmium stress can promote the expression of Bp HO,while the response patterns differ.