Chair of Plant Physiology and Biotechnology, Faculty of Biology and Environment Protection, Nicolaus Copernicus University, 1 Lwowska Street, 87-100 Torun, Poland; Centre for Modern Interdisciplinary Technologies, Nicolaus Copernicus University, 4 Wilenska Street, 87-100 Torun, Poland.
Chair of Plant Physiology and Biotechnology, Faculty of Biology and Environment Protection, Nicolaus Copernicus University, 1 Lwowska Street, 87-100 Torun, Poland; Centre for Modern Interdisciplinary Technologies, Nicolaus Copernicus University, 4 Wilenska Street, 87-100 Torun, Poland.
J Plant Physiol. 2014 Feb 15;171(3-4):225-34. doi: 10.1016/j.jplph.2013.07.011. Epub 2013 Oct 2.
The plant hormone auxin plays a critical role in regulating plant growth and development. Recent advances have been made that having improved our understanding of auxin response pathways, primarily by characterizing the genes encoding auxin response factors (ARFs) in Arabidopsis. In addition, the expression of some ARFs is regulated by microRNAs (miRNAs). In Arabidopsis thaliana, ARF6 and ARF8 are targeted by miR167, whereas ARF10, ARF16 and ARF17 are targeted by miR160. Nevertheless, little is known about any possible interactions between miRNAs and the auxin signaling pathway during plant development. In this study, we isolated the miR167 target gene InARF8 cDNA from the cotyledons of the short day plant (SDP) Ipomoea nil (named also Pharbitis nil). Additionally, the In-miR167 precursor was identified from the I. nil EST database and analyses of InARF8 mRNA, In-pre-miR167 and mature miR167 accumulation in the plant's vegetative and generative organs were performed. The identified cDNA of InARF8 contains a miR167 complementary sequence and shows significant similarity to ARF8 cDNAs of other plant species. The predicted amino acid sequence of InARF8 includes all of the characteristic domains for ARF family transcription factors (B3 DNA-binding domain, AUX/IAA-CTD and a glutamine-rich region). Quantitative RT-PCR reactions and in situ hybridization indicated that InARF8 was expressed primarily in the shoot apices, leaf primordia and hypocotyls of I. nil seedlings, as well as in flower pistils and petals. The InARF8 transcript level increased consistently during the entire period of pistil development, whereas in the stamens, the greatest transcriptional activity occurred only during the intensive elongation phase. Additionally, an expression analysis of both the precursor In-pre-miR167 molecules identified and mature miRNA was performed. We observed that, in most of the organs examined, the InARF8 expression pattern was opposite to that of MIR167, indicating that the gene's activity was regulated by mRNA cleavage. Our findings suggested that InARF8 and InMIR167 participated in the development of young tissues, especially the shoot apices and flower elements. The main function of MIR167 appears to be to regulate InARF8 organ localization.
植物激素生长素在调节植物生长和发育中起着关键作用。最近的进展提高了我们对生长素反应途径的理解，主要是通过鉴定拟南芥中编码生长素反应因子（ARF）的基因。此外，一些 ARF 的表达受到 microRNAs（miRNAs）的调节。在拟南芥中，ARF6 和 ARF8 被 miR167 靶向，而 ARF10、ARF16 和 ARF17 被 miR160 靶向。然而，在植物发育过程中，miRNA 与生长素信号通路之间的任何可能相互作用知之甚少。在这项研究中，我们从短日照植物（SDP）Ipomoea nil（也称为 Pharbitis nil）的子叶中分离出 miR167 靶基因 InARF8 cDNA。此外，从 I. nil EST 数据库中鉴定出 In-miR167 前体，并对植物营养器官和生殖器官中的 InARF8 mRNA、In-pre-miR167 和成熟 miR167 积累进行了分析。鉴定的 InARF8 cDNA 包含一个 miR167 互补序列，与其他植物物种的 ARF8 cDNA 具有显著的相似性。InARF8 的预测氨基酸序列包含 ARF 家族转录因子的所有特征结构域（B3 DNA 结合域、AUX/IAA-CTD 和富含谷氨酰胺的区域）。定量 RT-PCR 反应和原位杂交表明，InARF8 在 I. nil 幼苗的茎尖、叶原基和下胚轴，以及花雌蕊和花瓣中主要表达。在整个雌蕊发育过程中，InARF8 转录水平持续增加，而在雄蕊中，最大的转录活性仅发生在强烈伸长阶段。此外，对鉴定的前体 In-pre-miR167 分子和成熟 miRNA 进行了表达分析。我们观察到，在大多数检查的器官中，InARF8 的表达模式与 MIR167 相反，表明该基因的活性受到 mRNA 切割的调节。我们的研究结果表明，InARF8 和 InMIR167 参与了年轻组织的发育，特别是茎尖和花器官的发育。MIR167 的主要功能似乎是调节 InARF8 的器官定位。
