苹果ELO家族基因鉴定及其在低温胁迫下的表达分析

Bioinformatics Analysis of Apple ELO Gene Family and Its Expression Analysis Under Low Temperature Stress

为研究苹果ELO家族基因在蜡质合成及抗寒中的作用,利用生物信息的方法对苹果全基因组中的ELO家族成员进行鉴定与分析。结果表明,MdELO基因家族共包含7个成员,不均匀地分布在苹果的3条染色体(Chr2、Chr8和Chr15)上。MdELO蛋白包含211~305个不等的氨基酸残基,等电点在9.43~11.62之间。亚细胞定位结果表明,MdELO蛋白在细胞核、细胞膜和叶绿体中有分布。顺式作用元件分析表明,7个MdELO启动子上游2 000 bp序列分布有激素、环境适应性和逆境诱导等响应元件。进一步测定越冬期不同品种苹果枝条中的蜡质含量,结果显示,从初休眠期至萌芽期,蜡质含量呈逐渐下降趋势,且抗寒性强的‘俄矮元帅’蜡质含量显著高于‘宫崎短富’;从蜡质形态及枝条表皮形态来看,‘俄矮元帅’蜡质呈针芒状且分布紧密,其枝条表皮结构紧密,表面光滑,而‘宫崎短富’蜡质呈散块状,枝条表皮结构松散,表面粗糙;两种苹果枝条的脯氨酸含量、相对电导率和淀粉磷酸化酶活性随越冬期的延长呈先升后降的趋势,淀粉酶活性呈逐渐上升的趋势,其中‘俄矮元帅’各指标均高于‘宫崎短富’。综上表明‘俄矮元帅’抗寒性显著高于‘宫崎短富’。q RT-PCR分析发现,低温胁迫下苹果砧木垂丝海棠的叶和根中均能检测到ELO的表达,大部分基因表现出先升后降的趋势,在低温胁迫12或24 h表达量最高,说明该家族成员在植物抗寒中扮演着重要作用。

In order to study the role of apple ELO gene family in wax synthesis and cold resistance,bioinformatics methods were used to identify and analyze the ELO family members in the whole apple genome. The results showed that the MdELO gene family consisted of seven members,which were unevenly distributed on three apple chromosomes(Chr2,Chr8 and Chr15). The MdELO protein contains 211-305 amino acid residues with isoelectric points ranging from 9.43 to 11.62. The results of subcellular localization showed that MdELO protein was distributed in the nucleus,cell membrane and chloroplast.The analysis of cis-acting elements showed that the 2 000 bp sequences upstream of the seven MdELO promoters were distributed with response elements such as hormones,environmental adaptability and stress induction. The wax content in different apple cultivars was further determined,and the results showed that the wax content of‘Oregon Spur Delicious’ was significantly higher than that of‘Miyazaki’;On the other hand,from the it perspective of wax morphology and cuticle morphology,the wax of‘Oregon Spur Delicious’ was needle-like and closely distributed,and the cuticle structure of its branches was close and smooth,while the wax of‘Miyazaki’was loose and lumpy,and the cuticle structure of its branches was loose and the surface was rough. Additionally,the proline,relative electrical conductivity and starch phosphorylase of the two apple branches increased firstly and then decreased with the extension of the overwintering period,and the amylase increased gradually,among which the content and activity of all indexes of‘Oregon Spur Delicious’ were higher than that of‘Miyazaki’. The changes of the above indexes showed that the cold resistance of‘Oregon Spur Delicious’ was significantly higher than that of‘Miyazaki’.It was found that the expression of ELO family members can be detected in the roots and leaves through qRT-PCR analysis,and the expression level displayeded certain differences. Most of them showed a trend of rising first and then falling,and the expression level is the highest at 12 h or 24 h,indicating that this family members may play an important role in low temperature stress.