ABA-Hypersensitive Germination1 encodes a protein phosphatase 2C, an essential component of abscisic acid signaling in Arabidopsis seed
ABA-Hypersensitive Germination1 encodes a protein phosphatase 2C, an essential component of abscisic acid signaling in Arabidopsis seed
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DOI：
10.1111/j.1365-313x.2007.03107.x
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发表时间：
2007-06-01
期刊：
影响因子：
7.2
通讯作者：
Hirayama, Takashi
中科院分区：
文献类型：
--
作者：
Nishimura, Noriyuki;Yoshida, Tomo;Hirayama, Takashi
植物激素脱落酸（阿坝）调节植物生理上重要的胁迫和发育反应。为了揭示阿坝反应的机制，我们分离了几个新的ABA超敏感拟南芥突变体，命名为ahg（（A）在bar阿坝下-（h）在bar超敏感（g）在bar萌发下）。ahg 1 -1突变体在萌发和萌发后的生长过程中表现出对阿坝、NaCl、KCl、甘露醇、葡萄糖和蔗糖的敏感性，但在成年植株中没有表现出任何显著的表型。ahg 1 -1种子在层积前积累的阿坝略多，表现出较强的休眠性。图位克隆AHG 1基因后发现AHG 1 -1编码一种新的蛋白磷酸酶2C（PP 2C）的基因发生了无义突变。我们先前表明，ahg 3 -1突变体在AtPP 2CA基因中具有点突变，AtPP 2CA基因编码另一种PP 2C，其在种子中的阿坝反应中具有主要作用（Yoshida et al.，2006年b）。AHG 1 mRNA水平在干种子中较高，并在种子成熟后期增加-表达模式与ABI 5相似。转录组分析表明，在ABA处理的发芽种子中，许多种子特异性基因和ABA诱导基因在ahg 1 -1和ahg 3 -1突变体中的表达高于野生型。详细的分析表明AHG 1和AHG 3的功能之间存在差异。几十个基因在ahg 1 -1突变体中的表达比ahg 3 -1更强烈。启动子GUS分析表明，在种子中的重叠和不同的表达模式。此外，ahg 1 -1和ahg 3 -1双突变体比单基因突变体更敏感。这些结果表明，AHG 1在种子发育和萌发中具有特定的功能，部分与AHG 3共享。
The phytohormone abscisic acid (ABA) regulates physiologically important stress and developmental responses in plants. To reveal the mechanism of response to ABA, we isolated several novel ABA-hypersensitive Arabidopsis thaliana mutants, named ahg ((A) under bar ABA-(h) under bar ypersensitive (g) under bar ermination). ahg1-1 mutants showed hypersensitivity to ABA, NaCl, KCl, mannitol, glucose and sucrose during germination and post-germination growth, but did not display any significant phenotypes in adult plants. ahg1-1 seeds accumulated slightly more ABA before stratification and showed increased seed dormancy. Map-based cloning of AHG1 revealed that ahg1-1 has a nonsense mutation in a gene encoding a novel protein phosphatase 2C (PP2C). We previously showed that the ahg3-1 mutant has a point mutation in the AtPP2CA gene, which encodes another PP2C that has a major role in the ABA response in seeds (Yoshida et al., 2006b). The levels of AHG1 mRNA were higher in dry seeds and increased during late seed maturation - an expression pattern similar to that of ABI5. Transcriptome analysis revealed that, in ABA-treated germinating seeds, many seed-specific genes and ABA-inducible genes were highly expressed in ahg1-1 and ahg3-1 mutants compared with the wild-type. Detailed analysis suggested differences between the functions of AHG1 and AHG3. Dozens of genes were expressed more strongly in the ahg1-1 mutant than in ahg3-1. Promoter-GUS analyses demonstrated both overlapping and distinct expression patterns in seed. In addition, the ahg1-1 ahg3-1 double mutant was more hypersensitive than either monogenic mutant. These results suggest that AHG1 has specific functions in seed development and germination, shared partly with AHG3.