• The timing of leaf emergence at the shoot apical meristem, or plastochron, is highly regulated in plants. Among the genes known to regulate the plastochron in Arabidopsis (Arabidopsis thaliana), KLUH (KLU), orthologous to the rice (Oryza sativa) PLASTOCHRON1, encodes the cytochrome P450 CYP78A5, and is thought to act through generation of a still unknown mobile signal. As klu mutants display not only a short plastochron but also a branching phenotype reminiscent of strigolactone (SL) mutants, we investigated whether KLU/CYP78A5 is involved in SL biosynthesis.
• We combined a genetic approach, a parasitic plant seed germination bioassay to test klu root exudates, and analysis of transcript abundances of SL-biosynthesis genes in the Arabidopsis klu mutants.
• We demonstrate that KLU is not involved in the SL-biosynthesis pathway. Moreover, this work allowed us to uncover a new role for SL during Arabidopsis development in modulating plastochron via a KLU-dependent pathway.
• Globally our data reveal that KLU is required for plastochron-specific SL responses, a first indication of crosstalk between SL and the KLU-derived signal.

中文翻译：

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独脚金内酯 (SLs) 通过调节拟南芥中的 KLUH (KLU) 转录本丰度来调节 plastochron

• 在植物中，茎尖分生组织或 plastochron 的叶片出现时间受到高度调节。在已知调节拟南芥 ( Arabidopsis thaliana ) 中plastochron 的基因中，与水稻 ( Oryza sativa ) PLASTOCHRON1直系同源的KLUH ( KLU )编码细胞色素 P450 CYP78A5，并且被认为通过产生仍然未知的移动信号起作用。由于klu突变体不仅显示出短的 plastochron 还显示出让人想起独脚金内酯 (SL) 突变体的分支表型，我们研究了 KLU/CYP78A5 是否参与 SL 生物合成。
• 我们结合了遗传方法、寄生植物种子萌发生物测定法来测试klu根分泌物，并分析拟南芥klu突变体中 SL 生物合成基因的转录丰度。
• 我们证明 KLU 不参与 SL 生物合成途径。此外，这项工作使我们能够发现 SL 在拟南芥发育过程中通过依赖 KLU 的途径调节 plastochron 的新作用。
• 在全球范围内，我们的数据显示，特定于 plastochron 的 SL 响应需要 KLU，这是 SL 和 KLU 衍生信号之间串扰的第一个迹象。