Ethylene inhibits lateral root development, increases IAA transport and expression of PIN3 and PIN7 auxin efflux carriers
Ethylene inhibits lateral root development, increases IAA transport and expression of PIN3 and PIN7 auxin efflux carriers
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DOI：
10.1242/dev.065102
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发表时间：
2011-08-15
期刊：
影响因子：
4.6
通讯作者：
Muday, Gloria K.
中科院分区：
文献类型：
--
作者：
Lewis, Daniel R.;Negi, Sangeeta;Muday, Gloria K.
我们使用遗传和分子方法来确定气态植物激素乙烯减少侧根形成并增强生长素激素的极性运输的机制。拟南芥突变体 aux1、lax3、pin3 和 pin7 存在生长素流入和流出蛋白缺陷，在用乙烯前体 1-氨基环丙烷-1-羧酸 (ACC) 处理后，对侧根形成的抑制和生长素运输的刺激不太敏感。相比之下，pin2 和 abcb19 突变体表现出野生型 ACC 反应。 ACC和3-吲哚乙酸（IAA）分别以ETR1和EIN2（乙烯信号传导）依赖性和TIR1（生长素受体）依赖性方式增加编码生长素转运蛋白的转录本的丰度。 ACC 对这些转录本和侧根发育的影响在 tir1 突变体中仍然存在，表明独立的信号网络。 ACC 增加了根尖中生长素诱导的基因表达，但降低了侧根形成区域的表达，并减少了整个根中的游离 IAA。乙烯合成抑制剂氨基乙氧基乙烯基甘氨酸（AVG）对生长素依赖性基因表达具有相反的作用。这些结果表明 ACC 通过改变生长素分布来影响根部发育。 ACC 或 AVG 处理后，PIN3-和 PIN7-GFP 荧光分别增加或减少，与 PIN3 和 PIN7 在 ACC 升高的转运中的作用一致。 ACC 处理消除了 PIN3-和 PIN7-GFP 荧光的局部缺失，这种现象通常出现在原基形成位点下方。这些结果表明，ACC 处理增加了 PIN3 和 PIN7 的表达，导致生长素转运增加，从而阻止了驱动侧根形成所需的生长素的局部积累。
We used genetic and molecular approaches to identify mechanisms by which the gaseous plant hormone ethylene reduces lateral root formation and enhances polar transport of the hormone auxin. Arabidopsis thaliana mutants, aux1, lax3, pin3 and pin7, which are defective in auxin influx and efflux proteins, were less sensitive to the inhibition of lateral root formation and stimulation of auxin transport following treatment with the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC). By contrast, pin2 and abcb19 mutants exhibited wild-type ACC responses. ACC and indole-3-acetic acid (IAA) increased the abundance of transcripts encoding auxin transport proteins in an ETR1 and EIN2 (ethylene signaling)-dependent and TIR1 (auxin receptor)-dependent fashion, respectively. The effects of ACC on these transcripts and on lateral root development were still present in the tir1 mutant, suggesting independent signaling networks. ACC increased auxin-induced gene expression in the root apex, but decreased expression in regions where lateral roots form and reduced free IAA in whole roots. The ethylene synthesis inhibitor aminoethoxyvinylglycine (AVG) had opposite effects on auxin-dependent gene expression. These results suggest that ACC affects root development by altering auxin distribution. PIN3- and PIN7-GFP fluorescence was increased or decreased after ACC or AVG treatment, respectively, consistent with the role of PIN3 and PIN7 in ACC-elevated transport. ACC treatment abolished a localized depletion of fluorescence of PIN3- and PIN7-GFP, normally found below the site of primordia formation. These results suggest that ACC treatment increased PIN3 and PIN7 expression, resulting in elevated auxin transport, which prevented the localized accumulation of auxin needed to drive lateral root formation.