The evolution of the abscisic acid-response in land plants:: comparative analysis of group 1 LEA gene expression in moss and cereals
The evolution of the abscisic acid-response in land plants:: comparative analysis of group 1 LEA gene expression in moss and cereals
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DOI：
10.1007/s11103-005-0909-z
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发表时间：
2005-11-01
影响因子：
5.1
通讯作者：
Cuming, AC
中科院分区：
文献类型：
--
作者：
Kamisugi, Y;Cuming, AC
藓类小立碗藓具有单拷贝的组1莱亚基因，命名为Pp莱亚-1。Pp莱亚-1基因的序列分析揭示该基因在组1莱亚基因家族的所有成员中保守的位置含有单个内含子，而且在第一外显子内含有提前终止密码子。然而，PpLEA-1转录物在苔藓组织中积累，以响应渗透胁迫和植物生长调节剂脱落酸（阿坝）的施加。这种反应似乎是在转录水平介导的，和观察的基因表达的模式，表达PpLea-1：：GUS转基因的植物的组织化学染色报告表明，启动子优先响应阿坝的原丝，而渗透胁迫诱导的基因表达主要在配子体。通过在立碗藓原生质体中瞬时表达的启动子活性的定量分析表明，PpLEA-1启动子在响应阿坝和渗透胁迫时是高度活跃的。ABA介导的来自Pp莱亚-1启动子的转基因表达以与小麦组1莱亚基因E-m的高活性启动子驱动的水平相似的水平发生。Pp莱亚-1启动子的定点突变表明ABA诱导是通过ACGT核心基序介导的，该基序类似于高等植物莱亚基因的阿坝响应元件中所见。然而，尽管小麦E-m启动子在苔藓组织中有活性，但苔藓启动子在谷类细胞中没有活性：在用PpLEA-1：：GUS构建体转染的大麦糊粉层原生质体中没有检测到活性、ABA诱导的或其它活性。我们建议，阿坝激活苔藓细胞中的基因表达代表了一种祖先的状态，只有最低限度的要求启动子识别，而谷物细胞需要额外的因素与ABA响应启动子的相互作用。
The moss Physcomitrella patens possesses a single copy of a Group 1 LEA gene, designated PpLEA-1. Sequence analysis of the PpLEA-1 gene reveals the gene to contain a single intron in a position conserved in all members of the Group 1 LEA gene family, but also to contain a premature termination codon within the first exon. Nevertheless, a PpLEA-1 transcript accumulates in moss tissues in response both to the imposition of osmotic stress, and to the plant growth regulator abscisic acid (ABA). This response appears to be mediated at the transcriptional level, and observation of the pattern of gene expression, reported by histochemical staining of plants expressing a PpLea-1::GUS transgene suggests that the promoter responds preferentially to ABA in protonemal filaments, whereas osmotic stress induces gene expression primarily in the gametophores. Quantitative analysis of promoter activity by transient expression in Physcomitrella protoplasts shows the PpLEA-1 promoter to be highly active in response to ABA and osmotic stress. ABA-mediated transgene expression from the PpLea-1 promoter occurs at a level similar to that driven by the highly active promoter of the wheat Group 1 LEA gene, E-m. Site-directed mutagenesis of the PpLEA-1 promoter indicates that ABA-inducibility is mediated via an ACGT-core motif similar to that seen in the ABA response elements of higher plant LEA genes. However, whereas the wheat E-m promoter is active in moss tissues, the moss promoter is not reciprocally active in cereal cells: no activity, ABA-inducible or otherwise was detected in barley aleurone protoplasts transfected with the PpLEA-1::GUS construct. We propose that ABA activation of gene expression in moss cells represents an ancestral state, with only minimal requirements for promoter recognition, whereas cereal cells require the interaction of additional factors with ABA-responsive promoters.