Shoot-supplied ammonium targets the root auxin influx carrier AUX1 and inhibits lateral root emergence in Arabidopsis
Shoot-supplied ammonium targets the root auxin influx carrier AUX1 and inhibits lateral root emergence in Arabidopsis
复制标题
芽提供的铵靶向根生长素流入载体 AUX1 并抑制拟南芥侧根的出现
DOI：
10.1111/j.1365-3040.2011.02295.x
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发表时间：
2011-06-01
影响因子：
7.3
通讯作者：
Shi, Weiming
中科院分区：
文献类型：
--
作者：
Li, Baohai;Li, Qing;Shi, Weiming
大气中铵（NH 4+）的沉降是一个重要的环境问题。虽然对根部暴露于NH（4）+所产生的毒性进行了充分的研究，但对地上部供应的铵（SSA）如何影响根部生长知之甚少。在这项研究中，我们表明，SSA显着影响侧根（LR）的发展。我们发现，SSA抑制侧根原基（LRP）的出现，但不LRP启动，导致LR数量显着受损。我们表明，抑制是独立的脱落酸（阿坝）信号和蔗糖吸收芽，但涉及到生长素在根中的反应。生长素响应报告基因DR 5：GUS的表达分析和生长素运输的直接测定表明，SSA抑制根向顶（根顶）生长素运输，而不影响向基（根顶）运输或根细胞的生长素敏感性。突变体分析表明，生长素流入载体AUX 1，而不是生长素流出载体PIN-FORMED（PIN）1或PIN 2，需要这种抑制LRP出现和观察到的生长素反应。我们发现，AUX 1的表达调制SSA在维管组织，而不是LR帽细胞在根。两者合计，我们的研究结果表明，SSA抑制LRP出现在拟南芥中通过干扰AUX 1依赖的生长素运输从地上部到根。
Deposition of ammonium (NH(4)+) from the atmosphere is a substantial environmental problem. While toxicity resulting from root exposure to NH(4)+ is well studied, little is known about how shoot-supplied ammonium (SSA) affects root growth. In this study, we show that SSA significantly affects lateral root (LR) development. We show that SSA inhibits lateral root primordium (LRP) emergence, but not LRP initiation, resulting in significantly impaired LR number. We show that the inhibition is independent of abscisic acid (ABA) signalling and sucrose uptake in shoots but relates to the auxin response in roots. Expression analyses of an auxin-responsive reporter, DR5:GUS, and direct assays of auxin transport demonstrated that SSA inhibits root acropetal (rootward) auxin transport while not affecting basipetal (shootward) transport or auxin sensitivity of root cells. Mutant analyses indicated that the auxin influx carrier AUX1, but not the auxin efflux carriers PIN-FORMED (PIN)1 or PIN2, is required for this inhibition of LRP emergence and the observed auxin response. We found that AUX1 expression was modulated by SSA in vascular tissues rather than LR cap cells in roots. Taken together, our results suggest that SSA inhibits LRP emergence in Arabidopsis by interfering with AUX1-dependent auxin transport from shoot to root.