Department of Biochemistry and Cell Biology, Rice University, Houston, TX 77005, USA.
Plant Cell. 2009 Nov;21(11):3585-90. doi: 10.1105/tpc.108.065185. Epub 2009 Nov 10.
Silver nitrate and aminoethoxyvinylglycine (AVG) are often used to inhibit perception and biosynthesis, respectively, of the phytohormone ethylene. In the course of exploring the genetic basis of the extensive interactions between ethylene and auxin, we compared the effects of silver nitrate (AgNO(3)) and AVG on auxin responsiveness. We found that although AgNO(3) dramatically decreased root indole-3-acetic acid (IAA) responsiveness in inhibition of root elongation, promotion of DR5-beta-glucuronidase activity, and reduction of Aux/IAA protein levels, AVG had more mild effects. Moreover, we found that that silver ions, but not AVG, enhanced IAA efflux similarly in root tips of both the wild type and mutants with blocked ethylene responses, indicating that this enhancement was independent of ethylene signaling. Our results suggest that the promotion of IAA efflux by silver ions is independent of the effects of silver ions on ethylene perception. Although the molecular details of this enhancement remain unknown, our finding that silver ions can promote IAA efflux in addition to blocking ethylene signaling suggest that caution is warranted in interpreting studies using AgNO(3) to block ethylene signaling in roots.
硝酸银和氨基乙氧基乙烯基甘氨酸（AVG）常用于分别抑制植物激素乙烯的感知和生物合成。在探索乙烯与生长素广泛相互作用的遗传基础的过程中，我们比较了硝酸银（AgNO3）和 AVG 对生长素反应的影响。我们发现，尽管 AgNO3 显著降低了根伸长抑制、促进 DR5-β-葡糖苷酸酶活性和Aux/IAA 蛋白水平降低的根吲哚-3-乙酸（IAA）反应性，但 AVG 的影响更为温和。此外，我们发现银离子而非 AVG 以类似的方式增强了野生型和乙烯反应受阻突变体根尖的 IAA 外排，表明这种增强独立于乙烯信号。我们的结果表明，银离子促进 IAA 外排与银离子对乙烯感知的影响无关。尽管这种增强的分子细节尚不清楚，但我们发现银离子除了阻断乙烯信号外还可以促进 IAA 外排，这表明在使用 AgNO3 阻断根中乙烯信号的研究中需要谨慎。
