【摘要】 基于茶树转录组数据,以龙井43茶树cDNA为模板,克隆得到开放阅读框(ORF)长度为1 305 bp,编码434个氨基酸的茶树单脱氢抗坏血酸还原酶基因,命名为CsMDHAR。蛋白序列特征和基因表达模式分析表明,CsMDHAR蛋白含有FAD结合功能域,属于FAD依赖的吡啶核苷酸-硫基氧化还原酶(Pyr-redox-2)家族。该蛋白有两个无序化区域,而且包含有32个磷酸化位点,理论相对分子量为47.21 kDa,pI为5.99,属于亲水性蛋白;CsMDHAR蛋白二级结构以α-螺旋和随机卷曲为主。通过PlantCARE和PLACE对启动子上游调控元件进行分析预测,结果显示,CsMDHAR基因启动子上游1 000 bp中含有多个与光、激素以及植物抗逆有关的顺式作用元件。利用荧光定量PCR方法检测龙井43和迎霜的CsMDHAR、CsAO和CsAPX在4种不同非生物胁迫下的表达水平,结果表明,在低温(4℃)胁迫下,两个茶树品种的CsMDHAR、CsAO和CsAPX的表达均受抑制,且品种间的差异较小;在高温(38℃)和干旱(200 g·L-1 PEG)胁迫下龙井43中的CsMDHAR表达均上调,分别在8 h和2 h时达到最大值,为对照的1.49倍和1.85倍;盐(200 mmol·L-1 NaCl)胁迫下,CsAO和CsAPX在两种茶树品种中的表达量变化趋势相似,但变化幅度不同,可能与品种间不同的抗逆性有关。更多还原

【Abstract】 In this study, a MDHAR gene(CsMDHAR) was cloned from Camellia sinensis cv. ‘Longjing 43’ based on the transcriptome data of tea plant. Sequence analysis shows that the open reading frame length of CsMDHAR was 1 305 bp, encoding 434 amino acids with a molecular weight of approximately 47.21 kDa and the theoretical isoelectric point of 5.99. CsMDHAR was a hydrophilic protein, including two unordered regions and 32 phosphorylation sites. CsMDHAR belonged to Pyr-redox-2 super-family containing a highly conserved region called FAD domain, and mainly composed of α-helix and random coil. PlantCARE and PLACE database prediction analysis suggest that there were many cis-elements related to light, hormones and stress resistance in the 1 000 bp upstream region of CsMDHAR gene. The expression profiles of CsMDHAR, CsAO and CsAPX in tea cv ‘Longjing 43’ and ‘Yingshuang’ under high temperature, low temperature, drought, and salt treatments were detected by qRT-PCR. The results indicate that the expression profiles of CsMDHAR, CsAO and CsAPX were suppressed under 4℃, and there were no significantly differences in ‘Longjing 43’ and ‘Yingshuang’. However, the expression profiles of CsMDHAR gene were upregulated under 38℃ or 200 g·L-1 PEG treatments in ‘Longjing 43’, with the highest 2.5 and 5 times of the control at 8 h and 2 h, respectively. In addition, the expression trends of CsAO and CsAPX in both cultivars were similar under NaCl(200 mmol·L-1) treatment, but the variation ranges were different, which might be related to the different stress response in tea plant.更多还原