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甜菜碱醛脱氢酶(betaine aldehyde dehydrogenase,BADH)是甜菜碱(glycine betaine,GB)合成过程中的关键酶。为检测BADH基因在木薯(Manihot esculenta)不同组织中的表达差异,探究干旱与NaCl胁迫下其表达谱变化规律,本研究利用生物信息学方法分析和鉴定木薯BADH基因,定位MeBADHs在染色体上的位置以及确定5’端上游序列顺式作用元件;采用qRT-PCR测定BADH基因在木薯品种SC5根、块根、茎和叶中的表达差异,同时检测在PEG-6000模拟脱水胁迫、NaCl胁迫及自然干旱胁迫下MeBADHs基因的转录水平变化,采用相关试剂盒测定木薯中GB含量的变化。结果显示,MeBADHs两个基因在各组织之中均有表达,在块根中表达量显著高于根(P<0.05)。PEG-6000模拟干旱条件下,与0 h相比,1~2 h时MeBADH1和MeBADH2在叶、茎、根以及块根中的表达量变化不大;NaCl处理条件下,叶中MeBADH1在8 h表达量极显著高于0 h(P<0.01),而MeBADH2则在不同处理时间下的表达量水平相差不大,在茎和根中,MeBADHs在处理发生1 h时表达量水平极显著高于0 h(P<0.01);自然缺水干旱条件下,茎和根中MeBADH1和MeBADH2分别在6和18 d时的表达量极显著高于0 d(P<0.01)。PEG-6000处理下,GB含量出现了波动并呈现略增趋势;NaCl处理条件下GB含量在前期表达较稳定,8 h时剧烈响应,即出现下调趋势,24 h时GB含量显著低于0 h(P<0.05)。在自然干旱胁迫下,GB含量逐渐呈现上调趋势,并在9和15 d达到高峰,显著高于0 d(P<0.05)。研究结果为进一步研究木薯分子抗旱机制及新品种的选育提供了理论依据。
Betaine aldehyde dehydrogenase (BADH) is a key enzyme in the synthesis of glycine betaine (GB). In order to detect the difference of BADH gene expression in different tissues of Cassava (Manihot esculenta), we investigated the variation of BADH gene expression profile under drought and NaCl stress. In this study, bioinformatics methods were used to analyze and identify the BADH gene in Cassava and to locate the position of MeADHs on the chromosome And determine the cis-acting element upstream of the 5 ’end. The expression differences of BADH gene in root, shoot, stem and leaf of cassava variety SC5 were detected by qRT-PCR. Simultaneously, PEG-6000 simulated dehydration stress, NaCl stress and natural drought Under stress, the transcription level of MeBADHs gene was changed. The relative kit was used to determine the content of GB in cassava. The results showed that two genes of MeBADHs were expressed in all tissues, and the expression level of MeBADHs in root tuber was significantly higher than that in roots (P <0.05). Compared with 0 h, the expression levels of MeBADH1 and MeBADH2 in leaves, stems, roots and tubers did not change much at 1 ~ 2 h in PEG-6000 simulated drought conditions. MeBADH1 was expressed at 8 h after NaCl treatment The amount of MeBADH2 expression in the stems and roots at 1 h after treatment was significantly higher than that at 0 h (P <0.01) h (P <0.01). Under drought and drought conditions, the expression levels of MeBADH1 and MeBADH2 in stem and root at 6 and 18 d were significantly higher than those at 0 d (P <0.01). Under the treatment of PEG-6000, the content of GB fluctuated and showed a slight increase trend. Under NaCl treatment, the content of GB was stable in the early stage and responded strongly at 8 h, indicating the downward trend. The content of GB at 24 h was significantly lower than 0 h (P <0.05). Under natural drought stress, the content of GB gradually increased and reached the peak at 9 and 15 d, significantly higher than that at 0 d (P <0.05). The results provide a theoretical basis for further research on cassava molecular mechanism of drought resistance and selection of new varieties.