刺梨MDHAR基因家族表达特点及其参与AsA积累调控的关键成员鉴定

Expression characteristics of MDHAR gene family in Rosa roxburghii and identification of key members involved in AsA accumulation regulation

单脱氢抗坏血酸还原酶(monodehydroascorbate reductase,MDHAR)是抗坏血酸(L-ascorbic acid,AsA)循环再生途径中的关键酶,影响植物AsA的最终积累量。本文从刺梨基因组中共鉴定出10个编码MDHAR蛋白的基因,分别命名为RrMDHAR1-10;10个基因分别位于5条染色体上,可分为3个亚族;亚细胞定位预测显示大多数成员定位于叶绿体;各成员包含的外显子数目在1~17个之间,差别较大。共线性分析表明,刺梨MDHAR家族与野草莓存在3对直系同源基因,与猕猴桃存在6对直系同源基因。启动子顺式作用元件预测RrMDHAR基因大多具有激素、胁迫等顺式作用元件。qRT-PCR分析表明RrMDHAR基因具有明显的时空表达特点,且受外源激素如ABA、GA3、MeJA等的调控,其中RrMDHAR4和RrMDHAR8的表达变化与果实AsA含量变化呈显著正相关。本研究以刺梨为材料对AsA合成代谢通路上的相关基因进行鉴定和分析,有助于更好地了解植物果实中AsA高积累的原因,对通过现代基因工程手段改良品种、提高AsA积累具有重要的参考意义。

Monodehydroascorbate reductase(MDHAR)is a key enzyme in the recycling pathway of L-ascorbic acid(AsA),which affects the final accumulation of AsA in plants.In this paper,10 genes encoding MDHAR protein were identified from the genome of Rosa roxburghii,named RrMDHAR1-10 respectively.They are located on 5 chromosomes and can be divided into 3 subgroups.Subcellular localization prediction showed that most members were localized in chloroplasts.Besides,the number of exons in each gene member is between 1 and 17,with a large difference.Collinearity analysis displayed that there were 3 pairs of direct homologous MDHAR genes between Rosa roxburghii and wild strawberry,and 6 pairs of direct homologous MDHAR genes between Rosa roxburghii and kiwifruit.Promoter cis-acting elements predicted that most RrMDHAR genes have elements such as phytohormone responsiveness and stress responsiveness.QRT-PCR analysis exhibited that the RrMDHAR genes had obvious temporal and spatial expression characteristics.Meanwhile,they can be regulated by plant growth regulators such as ABA,GA3,MeJA,etc.Among them,the expression changes of RrMDHAR4 and RrMDHAR8 were significantly positively correlated with the changes of AsA content in fruits.In this study,Rosa roxburghii was used as material to identify and analyze the genes related to AsA anabolic pathway,which is helpful to better understand the reasons for the high accumulation of AsA in plant fruits.Besides,it has important reference significance for improving varieties and increasing AsA accumulation through modern genetic engineering.