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抗坏血酸过氧化物酶(ascorbate peroxidase,APX)作为植物抗氧化防御系统中的重要一员,在一定程度上决定着植物的抗逆性。茉莉酸甲酯(methyl jasmonate,Me JA)作为逆境信号物质可以诱导植物抗逆响应,但是能否诱导APX基因表达、其表达趋势如何到目前为止尚未见报道。我们根据拟南芥APX同源基因At APXIII(AJ006030.1)的序列在西瓜基因组数据库中搜索获得一个高度同源序列:Cla015833,命名为Cl APX1。我们对该基因进行了生物信息学分析并以二倍体西瓜细胞为材料,利用q RT-PCR技术对Cl APX1在茉莉酸甲酯诱导下的表达特性进行了研究。结果表明Cl APX1基因的转录起始位点位于起始密码子上游980 bp处,启动子区域包含典型启动子必须的调控元件,多个激素响应元件和逆境胁迫响应元件等;该基因编码的蛋白含有286个氨基酸,分子量为31.56 k D,理论等电点为6.67,此蛋白可能定位在细胞质中,属于c APX;该基因在亲缘关系上较为接近同科的黄瓜和甜瓜。在茉莉酸甲酯施加了0.5 h后Cl APX1基因的表达量高于本底水平,一直持续到8 h,变化呈现出先上升后下降的趋势。本研究说明了Cl APX1基因对茉莉酸甲酯模拟的逆境信号做出了响应且表达量提高。本研究为利用茉莉酸甲酯提高植物抗逆性提供了理论支持,为植物的APX基因对茉莉酸信号响应方式和表达调控趋势做了补充,为以后深入研究APX基因奠定基础。
Ascorbate peroxidase (APX), as an important member of antioxidant defense system in plants, to a certain extent determines plant stress resistance. Methyl jasmonate (Me JA) can induce plant stress response as a stress signal, but whether it can induce APX gene expression or not has not been reported yet. We searched the watermelon genome database for a highly homologous sequence based on the sequence of the Arabidopsis APX homology gene At APXIII (AJ006030.1): Cla015833, named Cl APX1. We carried out bioinformatics analysis of the gene and studied the expression characteristics of Cl APX1 induced by methyl jasmonate using q-RT-PCR from diploid watermelon cells. The results showed that the transcription initiation site of Cl APX1 gene was located 980 bp upstream of the start codon. The promoter region contained the regulatory elements, multiple hormone response elements and stress response elements required by typical promoters. The protein encoded by this gene Contains 286 amino acids with a molecular mass of 31.56 kD and a theoretical isoelectric point of 6.67. This protein may be localized in the cytoplasm and belongs to c APX. The gene is closer to the same families of cucumbers and melons in its genetic relationship. The expression level of Cl APX1 gene was higher than the background level after applying methyl jasmonate for 0.5 h and continued until 8 h. This study demonstrates that the Cl APX1 gene responds to and increases the expression of the adversity signal of methyl jasmonate. This study provides theoretical support for the use of methyl jasmonate to improve plant stress resistance, complements the response mode and expression regulation of jasmonic acid signal of plant APX gene, and lays the foundation for further study of APX gene in future.