ABSTRACT Strigolactones (SLs) and smoke-derived Karrikins (KARs) are structurally similar butenolide compounds that control distinct aspects of plant development. They are perceived by two closely related α/β hydrolases D14 and KAI2, respectively. Responses to both molecules involve the F-box protein MAX2 that participates in the Skp1-Cullin-F-box (SCF) complex, which ubiquitylates developmental regulators of the SMXL family to mark them for degradation by the 26S proteasome, enabling SL and KAR responses. Current research on SL and KAR signaling uses the synthetic molecules rac-GR24, KAR1 and KAR2 for pharmacological treatments. In a previous microarray analysis, we observed transcriptional activation in response to rac-GR24 in Lotus japonicus seedling roots. We retested transcript accumulation of selected genes by quantitative PCR in the wild type and the max2-4 mutant, and found that surprisingly, a number of them respond to rac-GR24 in a MAX2-independent manner, and also respond in roots of d14 and kai2a kai2b double mutants. Thus, the synthetic compounds induce transcriptional responses independent of their perception by the canonical receptor complex.

中文翻译：

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莲藕根中 rac-GR24 的 MAX2 独立转录反应

摘要 独脚金内酯 (SLs) 和烟雾衍生的 Karrikins (KARs) 是结构相似的丁烯内酯化合物，它们控制着植物发育的不同方面。它们分别被两个密切相关的 α/β 水解酶 D14 和 KAI2 感知。对这两种分子的反应涉及参与 Skp1-Cullin-F-box (SCF) 复合物的 F-box 蛋白 MAX2，该复合物泛素化 SMXL 家族的发育调节因子以标记它们被 26S 蛋白酶体降解，从而实现 SL 和 KAR 反应. 目前对 SL 和 KAR 信号传导的研究使用合成分子 rac-GR24、KAR1 和 KAR2 进行药物治疗。在之前的微阵列分析中，我们观察到莲藕幼苗根部响应 rac-GR24 的转录激活。我们通过定量 PCR 在野生型和 max2-4 突变体中重新测试了选定基因的转录物积累，并发现其中一些以不依赖 MAX2 的方式对 rac-GR24 产生反应，并且也在 d14 和kai2a kai2b 双突变体。因此，合成化合物诱导转录反应独立于它们被经典受体复合物的感知。