玉米逆境胁迫响应基因ZmTPR2的克隆和抗旱性分析

Cloning and Drought Tolerance Analysis of Maize Stress Responsive Gene ZmTPR2

四肽重复蛋白(Tetratricopeptide repeat proteins,TPR proteins)是一类属于螺旋重复蛋白超家族的蛋白成员,作为调节蛋白几乎参与了叶绿体合成和光合作用的所有步骤,并发挥重要作用,但是关于TPR蛋白是否参与植物响应非生物胁的报道较少。本研究通过转录组数据,在玉米中挖掘到一个响应干旱和复水过程的差异显著基因,该基因编码一个TPR蛋白,命名为ZmTPR2。ZmTPR2基因位于玉米的第3号染色体,编码421个氨基酸,且具有3个保守的卷曲螺旋结构域TRP,进化过程中与高粱亲缘性较高。RT-PCR结果显示,ZmTPR2基因属于组成型表达基因,在根、茎、叶、雄穗、雌穗等营养器官和生殖器官均表达,而在幼叶片中表达量最高。通过设置干旱、高温、高盐以及缺氮胁迫等模拟实验,发现该基因在4种胁迫下表达量均显著上调,干旱24 h时差异倍数达到峰值,为15.23倍。正常和干旱胁迫处理,ZmTPR2基因在抗旱型自交系郑58中的表达量均显著高于旱敏感自交系B73,其表达量与抗旱性密切相关。遗传转化获得过表达ZmTPR2拟南芥植株,与Col相比,干旱胁迫下过表达ZmTPR2拟南芥植株长势好,叶片含水量和叶绿素含量较高,而丙二醛(MDA)含量较低,超氧化物歧化酶(SOD)、过氧化物酶(POD)活性强,说明ZmTPR2在干旱胁迫下起正向调节作用。

Repeat four peptide protein(Tetratricopeptide repeat proteins TPR proteins) is a kind of protein that belongs to the spiral repeat protein superfamily member, as a regulatory proteins involved in the chloroplasts almost all of the steps and photosynthesis, and play an important role, However, there are few reports on whether TPR protein is involved in plant response to abiotic threats. In this study, through transcriptome data, a significantly different gene was discovered in maize(Zea mays L.) in response to drought and rehydration processes, which encoded a TPR protein named ZmTPR2. The gene, located on chromosome 3 of maize, encoded 421 amino acids and had three conserved coiled helix domains TRP. In the course of evolution, it was closely related to sorghum. The results of RT-PCR showed that ZmTPR2 gene was a constitutive expression gene, which was expressed in all vegetative organs and reproductive organs such as roots, stems, leaves, male ear and female ear, and the expression level was the highest in young leaves. Through the simulation experiments of drought, high temperature, high salt and nitrogen deficiency stress, it was found that the expression of this gene was significantly up-regulated under the four kinds of stress, and the difference ratio reached a peak of 15.23 times when the drought was 24 hours. The expression level of ZmTPR2 gene in drought tolerant inbred line Zheng58 was significantly higher than that in drought sensitive inbred line B73 under both normal and drought stress treatments, and its expression level was closely related to drought resistance. Arabidopsis thaliana plants overexpressing ZmTPR2 were obtained by genetic transformation. Compared with Col, Arabidopsis thaliana plants overexpressing ZmTPR2 under drought stress had better growth, higher leaf water content and chlorophyll content, lower content of malondialdehyde(MDA), and stronger activities of superoxide dismutase(SOD) and oxide dismutase(POD). These results indicated that ZmTPR2 played a positive regulatory role under drought stress.