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烟草NtPYL6表达模式及其调控芸香苷的合成功能分析

Expression pattern of NtPYL6 and its role in regulating rutin synthesis in tobacco

  • 摘要: 为探究ABA受体蛋白PYL在脱落酸(ABA)促进芸香苷合成过程中的作用,从栽培烟草基因组中克隆鉴定了NtPYL6基因,并进行了序列分析、表达模式检测、突变体创制及芸香苷含量检测。结果表明,NtPYL6参与了调控烟草中ABA诱导的芸香苷合成。栽培烟草基因组中有2个同源性较高的NtPYL6基因,分别命名为NtPYL6aNtPYL6b,其编码蛋白具有典型的PYR_PYL_RCAR_like结构域。基因表达水平分析显示,NtPYL6aNtPYL6b在烟草茎和叶片中表现出较高的转录活性,且表达量受ABA、油菜素内酯(BL)、茉莉酸甲酯(MeJA)和1-氨基环丙烷羧酸(ACC)的显著诱导。序列分析发现,NtPYL6a基因上游1 393 bp启动子片段中含有多种激素相关的转录调控元件,能够启动上述激素诱导的该基因表达。利用Crispr/cas9创制了ntpyl6突变体,发现与野生型相比,ntpyl6突变体对ABA处理的敏感性降低,且ABA诱导的芸香苷合成在突变体中被显著抑制。同时,还发现ntpyl6突变体中ABA对芸香苷合成相关基因的诱导作用被显著抑制,而在NtPYL6a过表达材料中基因表达水平被显著上调。可见,NtPYL6在ABA促进烟草芸香苷合成过程中发挥着作用,可为烟草品质改良育种提供新的靶标基因。

     

    Abstract: To investigate the role of Abscisic acid (ABA) receptor protein PYL in the promotion of rutin synthesis, a NtPYL6 gene was cloned and identified from Nicotiana tabacum genome, and its role in mediating ABA-induced rutin synthesis was verified by analyzing its sequences and expression patterns. An ntpyl6 mutant was generated and the rutin content in the mutant was determined. The results showed that NtPYL6 was involved in the regulation of ABA-induced rutin synthesis in tobacco. There were two close NtPYL6 genes in the cultivated tobacco genome, named NtPYL6a and NtPYL6b, respectively, which encoded proteins with typical PYR_PYL_RCAR_like domain. The results of gene expression level analysis showed that both NtPYL6a and NtPYL6b exhibited high transcriptional activity in tobacco stalks and leaves, and their expression was significantly induced by ABA, BL, MeJA, and ACC. The results of sequence analysis showed that there were several hormone-related transcriptional regulators in the promoter fragment located at 1 393 bp upstream of the NtPYL6a gene, which could activate the expressions of the above-mentioned genes induced by hormones. The ntpyl6 mutant was generated using the Crispr/cas9 method. Compared with WT plants, the ntpyl6 mutant showed reduced sensitivity to ABA treatment, and ABA-induced rutin synthesis was significantly inhibited in this mutant. Moreover, the ABA-induced expressions of rutin synthesis-related genes were significantly inhibited in the ntpyl6 mutant, and the expression levels of these genes were significantly up-regulated in NtPYL6a overexpression plants. Therefore, NtPYL6 was involved in promoting ABA-induced rutin synthesis and provided a new target gene for tobacco quality improvement breeding.

     

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