Institute of Plant Sciences, Agricultural Research Organization, The Volcani Center, PO Box 6, Bet Dagan 50250, Israel.
J Exp Bot. 2011 May;62(8):2915-24. doi: 10.1093/jxb/erq464. Epub 2011 Feb 9.
Strigolactones (SLs) or derivatives thereof have been identified as phytohormones, and shown to act as long-distance shoot-branching inhibitors. In Arabidopsis roots, SLs have been suggested to have a positive effect on root-hair (RH) elongation, mediated via the MAX2 F-box. Two other phytohormones, auxin and ethylene, have been shown to have positive effects on RH elongation. Hence, in the present work, Arabidopsis RH elongation was used as a bioassay to determine epistatic relations between SLs, auxin, and ethylene. Analysis of the effect of hormonal treatments on RH elongation in the wild type and hormone-signalling mutants suggested that SLs and ethylene regulate RH elongation via a common regulatory pathway, in which ethylene is epistatic to SLs, whereas the effect of SLs on RH elongation requires ethylene synthesis. SL signalling was not needed for the auxin response, whereas auxin signalling was not necessary, but enhanced RH response to SLs, suggesting that the SL and auxin hormonal pathways converge for regulation of RH elongation. The ethylene pathway requirement for the RH response to SLs suggests that ethylene forms a cross-talk junction between the SL and auxin pathways.
独脚金内酯（SLs）或其衍生物已被鉴定为植物激素，被证明作为远距离分枝抑制剂发挥作用。在拟南芥根中，SLs 被认为通过 MAX2 F-box 对根毛伸长有正向作用。另外两种植物激素，生长素和乙烯，也被证明对根毛伸长有正向作用。因此，在本工作中，拟南芥根毛伸长被用作生物测定法来确定 SLs、生长素和乙烯之间的上位性关系。激素处理对野生型和激素信号突变体中根毛伸长的影响分析表明，SLs 和乙烯通过一个共同的调节途径调节根毛伸长，其中乙烯在 SLs 上位，而 SLs 对根毛伸长的影响需要乙烯合成。SL 信号传导对于生长素的响应是不需要的，而生长素信号传导虽然不是必需的，但增强了对 SLs 的根毛响应，这表明 SL 和生长素激素途径在调节根毛伸长方面是会聚的。SL 对根毛响应的乙烯途径要求表明，乙烯在 SL 和生长素途径之间形成了一个交叉对话连接点。
