辣椒定位于叶绿体的13-脂氧合酶基因(CaLOX2)克隆及表达分析  

Cloning and Expression Characterization of Chloroplast-targeted 13-lipoxygenase Gene(CaLOX2) in Capsicum annuum L.

作　　者：贾庆利[1] 巩振辉[1,2] 李大伟[1,2] 

机构地区：[1]西北农林科技大学园艺学院,杨凌712100 [2]西北农林科技大学旱区作物逆境生物学国家重点实验室,杨凌712100

出　　处：《农业生物技术学报》2012年第10期1126-1134,共9页Journal of Agricultural Biotechnology

基　　金：国家自然科学基金(No.30571262);"十二五"农村领域国家科技计划(No.2011BAD12B00)

摘　　要：植物脂氧合酶参与环境胁迫应答,并在植物生长发育过程中起重要的作用。利用电子克隆及RT-PCR技术从辣椒(Capsicum annuum)中分离出一个脂氧合酶基因,该基因cDNA全长2843bp,含有一个2730bp的完整开放阅读框(ORF),编码910个氨基酸,该基因命名为CaLOX2(GenBank登录号:JQ219046)。序列分析表明,CaLOX2基因编码的氨基酸序列含有脂氧合酶保守结构域,定位于叶绿体基质内。系统进化树分析表明,CaLOX2属于TypeⅡ型13-LOX基因,和番茄(Solanum lycopersicum)TomLOXD、马铃薯(Solanum tuberosum)StLOXH3、野生烟草(Nicotiana attenuate)NaLOX3基因同源性高。实时定量PCR分析显示,CaLOX2在辣椒各个器官都表达,但其表达水平具有组织特异性,在叶片中表达量最高,在花中表达量最低;CaLOX2基因在辣椒与疫霉菌(Phytophthora capsici)亲和与非亲和互作中均受诱导,但在非亲和组合中受诱导表达的强度更大,并且诱导表达的时间在非亲和组合中也相对较早,表明CaLOX2与辣椒疫霉菌专化型抗性有关。辣椒不同器官接种疫霉菌后该基因表达模式也有差异,叶部接种诱导后CaLOX2基因的表达相对于根部接种诱导的强度要更剧烈一些,且最高峰较根部接种的延迟。机械伤害和高盐胁迫诱导该基因上调表达,低温抑制其表达,植物激素茉莉酸甲酯、水杨酸和H2O2均诱导其上调表达。和已知生物学功能的其他植物脂氧合酶基因聚类及表达模式比较揭示,CaLOX2可能参与茉莉酸而不是C6醛类合成。这些结果表明,CaLOX2基因可能通过水杨酸和茉莉酸信号途径参与辣椒对疫霉菌及低温、高盐等逆境条件的防卫反应。该研究为阐明CaLOX2基因在辣椒抗疫病和抗逆反应中的功能提供了基础资料。Plant lipoxygenases（LOX） play an important role in plant response to environmental stress, as well as in plant growth and development. A novel LOX gene designated as CaLOX2（GenBank accession number： JQ219046） was isolated using in silico cloning from Capsicum annuum L. and characterized by RT-PCR. The length of the gene was 2 843 bp, which contained a 2 730 bp long open reading frame（ORF）, coding a 910 animo acid polypeptide. The deduced amino acid sequence of the gene contained the typical domain of lipoxygenase and putative transit peptides for chloroplast import. Phylogenetic analysis revealed that CaLOX2 clustered together with well-characterized plastidic typeⅡ13-LOXs genes from tomato（Solanum lycopersicum）TomLOXD, potato（Solanum tuberosum） StLOXH3 and tobacco（Nicotiana attenuate） NaLOX3. Real-time quantitative PCR analysis showed that CaLOX2 transcripts were expressed in all tissues of pepper, however the expression patterns of the gene had tissue specificity,the transcripts were most abundantly expressed in the leaf but much less in flower; the expression level of the CaLOX2 mRNA could be up-regulated significantly after inoculation with zoospores of Phytophthora capsici in both incompatible and compatible interaction. But, its expression level was much higher and earlier at time point in the incompatible interaction than that in the compatible interaction., which indicated CaLOX2 was involed in race-specific resistance to Phytophthora capsici in pepper. The gene expression patterns differed in different pepper organs, its expression level was much higher but later at time point in the leaves than that in the roots after inoculated with Phytophthora capsici race ph1. The expression of CaLOX2 was up-regulated after treatment with mechanical wounding and NaCl stress, but down-regulated by low temperature. This gene was highly induced by H2O2, salicylic acid （SA）, and methy jasmonic acid （MeJA）. The comparison of CaLOX2 with the well-studied LOXs from other plant species in

关 键 词：辣椒 脂氧合酶 茉莉酸 基因表达 

分 类 号：S436.413.1[农业科学—农业昆虫与害虫防治]