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作 者 ：张 曼1,羊杏平1*,王薇薇1,2,徐锦华1,刘 广1,姚协丰1,李苹芳1

期 刊 ：西北植物学报 2013年 5期 页码：872~877

关键词：西瓜；植物防御素；基因克隆；表达分析；

Keywords:watermelon, plant defensin-like gene, gene cloning, expression analysis,

摘 要 ：该研究从西瓜中克隆了西瓜防御素基因ClPDF2.1（GenBank登录号为KC481267）。序列分析结果表明,ClPDF2.1基因开放阅读框为225 bp,编码75个氨基酸,预测蛋白质分子质量为8.237 kD,等电点为9.375。蛋白质结构分析表明,ClPDF2.1蛋白含有防御素特有的8个半胱氨酸结构域。进化分析显示,ClPDF2.1与拟南芥PDF2归为一类,与五彩椒的亲缘关系最近（59%）。荧光定量PCR分析表明,ClPDF2.1在西瓜根、茎、叶器官中都有表达,叶中表达量高于根,茎中表达量最低。ClPDF2.1基因的表达也受到外源植物激素水杨酸、茉莉酸甲酯、乙烯利和西瓜枯萎病菌的诱导上调,表明ClPDF2.1基因通过信号传导途径参与对西瓜枯萎病菌株的防御反应。西瓜防御素基因的克隆及表达分析为其功能鉴定奠定了基础。

Abstract:In this work,a defensin-like cDNA sequence was cloned from watermelon,named ClPDF2.1 (GenBank accession No.KC481267).Bioinformatics analysis showed that ClPDF2.1 encodes a putative polypeptide of 75 amino acids with a calculated molecular mass of 8.237 kD and a theoretical pI of 9.375.Sequence alignment showed that ClPDF2.1 had high homology to known PDF proteins from other plant species and contained the conserved eight cysteines motif.Phylogenetic analysis indicated that ClPDF2.1 belonged to the Arabidopsis PDF2 cluster,and was close to Capsicum annuum PDF gene with an overall sequence identity of 59%.Real-time PCR analysis revealed that ClPDF2.1 expressed in all tissues examined,with the highest in leaves,second in roots and the lowest in stems.Expression profiles under different treatments such as abscisic acid (SA),methyl jasmonate (JA),ethephon (ETH) and Fusarium wilt were compared,and the results revealed that transcriptional level of ClPDF2.1 was obviously up-regulated.These results suggested that ClPDF2.1 is probably employed the signal pathways to defense against Fusarium wilt pathogen.

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