New Phytol|中科院土壤所李光杰团队揭示WRKY46通过负调控NUDX9和IAA结合基因抑制NH4+外流。

铵（NH4+）对大多数已经处于中等水平的植物的根系生长是有毒的。转录调控是植物对NH4+毒害反应的重要机制之一，但转录因子（TFs）参与这种调控的性质尚不清楚。

在这里，对拟南芥根进行RNA-seq分析以筛选对铵离子敏感的TFs。选择对NH4+最敏感的WRKY转录因子家族成员WRKY46。我们通过突变和过表达分析确定了WRKY46的作用，并通过酵母单杂交、电泳迁移率转移分析和芯片定量PCR鉴定了WRKY46对NUDX9和IAA结合基因的调控。

WRKY46基因敲除增加，而WRKY46过表达减少，NH4+抑制初生根。WRKY46直接与NUDX9和IAA结合基因（GH3.1，GH3.6，UGT75D1，UGT84B2）的启动子结合并抑制其转录，从而积极调节游离IAA含量并稳定蛋白质N-糖基化，导致抑制根伸长区（EZ）中NH4+的外流。

我们鉴定了TF参与调节EZ的NH4+外流，并表明WRKY46通过负调控NUDX9和IAA结合基因抑制NH4+外流。

Ammonium (NH4+) is toxic to root growth in most plants already at moderate levels. Transcriptional regulation is one of the most important mechanisms in plant’s response to NH4+ toxicity, but the nature of the involvement of transcription factors (TFs) in this regulation remains unclear.

Here, RNA-seq analysis in Arabidopsis roots was performed to screen ammonium-responsive TFs. WRKY46, the member of the WRKY transcription factor family most responsive to NH4+, was selected. We define the role of WRKY46 by using mutation and overexpression assays, and characterize the regulation of NUDX9 and IAA-conjugating genes by WRKY46 via yeast one-hybrid and electrophoretic mobility shift assays and ChIP-quantitative PCR.

Knockout of WRKY46 increased, while overexpression of WRKY46 decreased, NH4+-suppression of the primary root. WRKY46 is shown to directly bind to the promoters of the NUDX9 and IAA-conjugating genes (GH3.1, GH3.6, UGT75D1, UGT84B2) and inhibits their transcription, thus positively regulating free IAA content and stabilizing protein N-glycosylation, leading to an inhibition of NH4+ efflux in the root elongation zone (EZ).

We identify TF involvement in regulating NH4+ efflux in the EZ, and show that WRKY46 inhibits NH4+ efflux by negative regulation of NUDX9 and IAA-conjugating genes.

https://nph.onlinelibrary.wiley.com/doi/pdf/10.1111/nph.17554?af=R

文章来源原创；转载请注明来源。

温馨提示：

为方便PaperRSS粉丝们科研、就业等话题交流。我们根据10多个专业方向（植物、医学、药学、人工智能、化学、物理、财经管理、体育等），特建立了30个国内外博士交流群。群成员来源欧美、日韩、新加坡、清华北大、中科院等全球名校。