NtNAC-R1, a novel NAC transcription factor gene in tobacco roots, responds to mechanical damage of shoot meristem
NtNAC-R1, a novel NAC transcription factor gene in tobacco roots, responds to mechanical damage of shoot meristem
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DOI：
10.1016/j.plaphy.2013.05.004
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发表时间：
2013-08-01
影响因子：
6.5
通讯作者：
Liu, Weiqun
中科院分区：
文献类型：
--
作者：
Fu, Yunpeng;Guo, Hongxiang;Liu, Weiqun
打顶是烤烟的重要农艺措施，打顶会导致上部烟叶烟碱含量的增加。烟碱含量是影响烟叶质量的重要因素之一。尼古丁只在烟草根中合成，然后通过木质部运输到叶片。为了研究打顶后烟碱生物合成能力增强的分子机制，分析了烟草根系对打顶的一些反应，并讨论了NtNAC-R1在调控烟碱合成和根发育中的作用。将电子克隆技术与RT-PCR技术相结合，成功地克隆了烟草根部NtNAC-R1基因。打顶后烟叶侧根数量增加，烟碱含量增加。叶面喷施MeJA对根系表型没有影响，但显著增加了烟碱含量和PMT的表达。打顶后，miR164基因在烟草根中表达下调，NtNAC-R1基因在烟草根中表达上调。在NtNAC-R1反义转基因烟草中，PMT和ODC表达下调，而在NtNAC-R1过表达的转基因烟草中PMT表达上调。综上所述，打顶可诱导根系miR164减少，IAA含量增加，从而上调NtNAC-R1的表达，从而导致侧根和烟碱含量的增加。同时，打顶是一种机械伤害，可以诱导茉莉酸信号，茉莉酸能促进烟草根部烟碱的生物合成。因此，打顶后烟碱生物合成能力的提高可能与JA和生长素信号通路的相互作用有关。(C)2013年爱思唯尔·马森公司。版权所有。
Topping is the important agronomic measure for flue-cured tobacco, and results in increase of the nicotine content in top leaves. Nicotine content is one of the vitals factors for the quality of tobacco leaves. Nicotine is exclusively synthesized in tobacco roots, and then transported to the leaves through the xylem. To investigate the molecular mechanism of increase in nicotine biosynthesis ability following topping, some responses of tobacco roots to topping were analyzed, and the role of NtNAC-R1 in regulating nicotine synthesis and the development of roots was discussed. The electronic cloning technique combined with RT-PCR was successfully used to clone NtNAC-R1 from tobacco roots. The number of lateral root and nicotine contents in tobacco roots increased following topping. Although spraying MeJA on leaves had no effects on the root phenotype, the nicotine contents and the expression of PMT increased markedly. The miR164 was down-regulated, and NtNAC-R1 was up-regulated in tobacco roots after topping. PMT and ODC were down-regulated in transgenic tobacco with antisense NtNAC-R1, and PMT was up-regulated in transgenic tobacco with over-expressed NtNAC-R1. In conclusion, topping can induce the decrease of miR164 and the increase of IAA content in roots, which up-regulate the expression of NtNAC-R1, resulting in the increase of lateral roots and nicotine contents. Meanwhile, topping is a mechanical wounding which can induce JA signal, and JA can enhance nicotine biosynthesis in tobacco roots. So the increase of nicotine biosynthesis ability would be related to cross-talking of JA and auxin signaling pathway after topping. (C) 2013 Elsevier Masson SAS. All rights reserved.