陆地棉ACX基因家族的鉴定与功能分析

Identification and functional analysis of the ACX gene family in Gossypium hirsutum L.

【目的】通过对陆地棉酰基辅酶A氧化酶(acyl coenzyme A oxidase,ACX)基因家族进行鉴定和表达分析,为后续研究ACX基因的功能奠定基础。【方法】采用生物信息学方法对陆地棉基因组中ACX基因家族成员进行鉴定,并系统分析其理化性质、基因结构、进化关系、基因复制、启动子区顺式作用元件和表达模式等。利用病毒诱导的基因沉默技术初步探究GhACX16基因的功能。【结果】陆地棉基因组中鉴定到20个ACX基因,分布在13条染色体上,聚类分析将其分为4个亚族。非同义突变率/同义突变率(Ka/Ks)分析结果表明陆地棉ACX家族基因经历了较强烈的纯化选择。ACX基因的启动子区含有热应激、干旱、植物激素响应等相关的顺式作用元件。非生物胁迫下的表达模式分析结果显示,陆地棉ACX基因明显响应高温、低温、盐和模拟干旱胁迫;分析高温胁迫下耐高温与高温敏感棉花材料不同发育时期的花药中ACX基因的表达模式,发现GhACX5和GhACX16基因的表达量变化明显。与阴性对照相比,高温胁迫下GhACX16基因沉默的棉苗表现出明显的耐高温特征,且叶片中脯氨酸含量、叶绿素含量和过氧化氢酶活性显著升高,而丙二醛含量显著降低。【结论】陆地棉ACX基因的鉴定及表达模式分析表明,ACX基因广泛参与非生物胁迫响应;经基因沉默试验和生理生化分析初步推测其中的GhACX16基因可能在高温胁迫响应中发挥重要的功能。

[Objective]The acyl-coenzyme A oxidase(ACX)gene family was identified in Gossypium hirsutum and their expression patterns were analyzed,which would lay the foundation for further studies of the function of ACX genes.[Method]The members of ACX gene family in G.hirsutum genome were identified by bioinformatics method,and their physical and chemical properties,gene structure,evolutionary relationships,gene replication,cis-acting elements in promoter region and expression patterns were analyzed systematically,and the virus-induced gene silencing(VIGS)technique was used to preliminary explore the function of GhACX16 gene.[Results]A total of 20 ACX genes were identified in G.hirsutum genome and distributed on 13 chromosomes,which were divided into 4 subfamilies by cluster analysis.The results of non-synonymous mutation rate/synonymous mutation rate(Ka/Ks)analysis showed that the ACX genes in G.hirsutum had undergone strong purifying selection.The promoter region of ACX genes contain cis-acting elements related to heat stress,drought,plant hormone responses,etc.The expression patterns under abiotic stresses showed that the ACX genes responded obviously to high-temperature,low-temperature,salt,and simulated drought stress.The expression patterns of ACX genes in the anthers at different developmental stages of high temperature-tolerant/sensitive cotton lines under high temperature conditions were analyzed,and it was found that the expression levels of GhACX5 and GhACX16 changed obviously.Compared with the negative control,the GhACX16 silenced cotton seedlings showed obvious characteristics of high temperature tolerance,and the proline content,chlorophyll content,and catalase activity were significantly higher,while the malondialdehyde content was significantly lower in the leaves.[Conclusion]The identification and expression patterns of ACX genes in G.hirsutum showed that ACX genes were widely involved in abiotic stresses response,and GhACX16 gene was preliminary speculated to play an important role in high temperature stress response according to the VIGS verification and physiological and biochemical analysis.