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植物生长发育过程中会遭遇各种病原物的攻击,植物为了应对这些危害并适应外界的生存竞争,逐渐演化出了复杂的防御机制。NHL基因家族庞大,部分NHL基因受病原物诱导后会过量表达,增强植物对多种病原菌的抗性,是与植物防御机制密切相关的蛋白。本研究以津南实芹和美国西芹2个芹菜品种为试验材料,分别克隆出NHL-like蛋白基因AgNHL。序列分析表明,上述2种芹菜的AgNHL基因序列均含636 bp的开放阅读框,编码211个氨基酸。2种芹菜碱基序列,只有第36位不同,津南实芹为T,美国西芹为C,2种碱基序列相似性高达99.84%,编码的氨基酸序列相同。进化分析显示,2种芹菜的NHL-like蛋白与葡萄、大豆等植物的相似度较高,在第80~185氨基酸间含一个LEA-2蛋白保守结构域。荧光定量PCR结果表明,AgNHL基因主要在芹菜茎中表达,根中表达量最低,有明显组织特异性,品种差异也很显著。对2种芹菜分别进行4℃低温、38℃高温、20%PEG处理、0.2 mol/L NaCl处理2 h表达分析显示,低温、盐处理下该基因表达量明显上升。
Plant growth and development process will encounter a variety of pathogenic attacks, plants in order to deal with these hazards and adapt to the survival of the outside world competition, gradually evolved a complex defense mechanism. NHL gene family is huge. Some NHL genes are overexpressed after being induced by pathogens to enhance the resistance of plants to various pathogens and are closely related to plant defense mechanisms. In this study, we used two celery cultivars, Jinnan Shiqin and American celery, as experimental materials to clone the NHL-like protein gene AgNHL. Sequence analysis showed that the two celery AgNHL gene sequences contained a 636 bp open reading frame encoding 211 amino acids. The two kinds of celery base sequences were different only from the 36th position, T from Jinnan, T and C from American celery. The similarity of the two kinds of base sequences was as high as 99.84%, which encoded the same amino acid sequence. Phylogenetic analysis showed that the two kinds of celery NHL-like proteins have high similarity with plants such as grapes and soybean, and contain a LEA-2 conserved domain between amino acids 80 and 185. Fluorescent quantitative PCR results showed that AgNHL gene was mainly expressed in celery stems, the lowest expression in roots, with obvious tissue specificity, the difference was also significant. The expression analysis of two kinds of celery under the conditions of 4 ℃ low temperature, 38 ℃ high temperature, 20% PEG treatment and 0.2 mol / L NaCl treatment for 2 h showed that the expression of the gene increased obviously under low temperature and salt treatment.