Liu Po-Pu, Montgomery Taiowa A, Fahlgren Noah, Kasschau Kristin D, Nonogaki Hiroyuki, Carrington James C
Department of Horticulture, Oregon State University, Corvallis, OR 97331, USA.
Plant J. 2007 Oct;52(1):133-46. doi: 10.1111/j.1365-313X.2007.03218.x. Epub 2007 Aug 2.
AUXIN RESPONSE FACTORS (ARFs) are transcription factors involved in auxin signal transduction during many stages of plant growth development. ARF10, ARF16 and ARF17 are targeted by microRNA160 (miR160) in Arabidopsis thaliana. Here, we show that negative regulation of ARF10 by miR160 plays important roles in seed germination and post-germination. Transgenic plants expressing an miR160-resistant form of ARF10, which has silent mutations in the miRNA target site (termed mARF10), exhibited developmental defects such as serrated leaves, curled stems, contorted flowers and twisted siliques. These phenotypes were not observed in wild-type plants or plants transformed with the targeted ARF10 gene. During sensu stricto germination and post-germination, mARF10 mutant seeds and plants were hypersensitive to ABA in a dose-dependent manner. ABA hypersensitivity was mimicked in wild-type plants by exogenous auxin. In contrast, overexpression of MIR160 (35S:MIR160) resulted in reduced sensitivity to ABA during germination. Transcriptome analysis of germinating ARF10 and mARF10 seeds indicated that typical ABA-responsive genes expressed during seed maturation were overexpressed in germinating mARF10 seeds. These results indicate that negative regulation of ARF10 by miR160 plays a critical role in seed germination and post-embryonic developmental programs, at least in part by mechanisms involving interactions between ARF10-dependent auxin and ABA pathways.
生长素响应因子（ARFs）是在植物生长发育的许多阶段参与生长素信号转导的转录因子。在拟南芥中，ARF10、ARF16和ARF17是微小RNA160（miR160）的作用靶点。在此，我们表明miR160对ARF10的负调控在种子萌发及萌发后过程中发挥重要作用。表达一种对miR160具有抗性的ARF10形式（在miRNA靶位点有沉默突变，称为mARF10）的转基因植物表现出发育缺陷，如叶片锯齿状、茎卷曲、花扭曲和角果扭曲。在野生型植物或用靶向的ARF10基因转化的植物中未观察到这些表型。在严格意义上的萌发和萌发后阶段，mARF10突变体种子和植物对脱落酸（ABA）呈剂量依赖性超敏感。外源生长素在野生型植物中模拟了ABA超敏感性。相反，MIR160过表达（35S:MIR160）导致萌发期间对ABA的敏感性降低。对萌发的ARF10和mARF10种子进行转录组分析表明，在种子成熟期间表达的典型ABA响应基因在萌发的mARF10种子中过度表达。这些结果表明，miR160对ARF10的负调控在种子萌发和胚后发育程序中起关键作用，至少部分是通过涉及ARF10依赖性生长素和ABA途径之间相互作用的机制实现的。
