The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture and The Otto Warburg Minerva Center for Agricultural Biotechnology, Hebrew University, P.O. Box 12, Rehovot 76100, Israel.
Plant J. 2012 Jun;70(6):903-15. doi: 10.1111/j.1365-313X.2012.04939.x. Epub 2012 Mar 31.
Compound leaves produce leaflets in a highly controlled yet flexible pattern. Here, we investigate the interaction between auxin, the putative auxin response inhibitor ENTIRE (E, SlIAA9) and the CUC transcription factor GOBLET (GOB) in compound-leaf development in tomato (Solanum lycopersicum). Auxin maxima, monitored by the auxin response sensor DR5, marked and preceded leaflet and lobe initiation. The DR5 signal increased, but maxima were partially retained in response to the external or internal elevation of auxin levels. E directly interacted with the auxin receptors SlTIR1 and SlAFB6. Furthermore, E was stabilized by a mutation in domain II of the protein and by the inhibition of auxin or proteasome activity, implying that E is subjected to auxin-mediated degradation. In e mutants the DR5 signal expanded to include the complete leaf margin, and leaf-specific overexpression of a stabilized form of E inhibited the DR5 signal and lamina expansion. Genetic manipulation of GOB activity altered the distribution of the DR5 signal, and the inhibition of auxin transport or activity suppressed the GOB overexpression phenotype, suggesting that auxin mediates GOB-regulated leaf patterning. Whereas leaves of single e or gob mutants developed only primary leaflets, the downregulation of both E and GOB resulted in the complete abolishment of leaflet initiation, and in a strong DR5 signal throughout the leaf margin. These results suggest that E and GOB modulate auxin response and leaflet morphogenesis via partly redundant pathways, and that proper leaflet initiation and separation requires distinct boundaries between regions of lamina growth and adjacent regions in which growth is inhibited.
复叶以高度受控且灵活的模式产生小叶。在这里，我们研究了生长素、假定的生长素反应抑制剂 E（ENTIRE，SlIAA9）和 CUC 转录因子 GOBLET（GOB）在番茄（Solanum lycopersicum）复叶发育中的相互作用。生长素最大浓度由生长素反应传感器 DR5 监测，标记并先于小叶和裂片的起始。DR5 信号增加，但在响应外部或内部生长素水平升高时，最大浓度部分保留。E 与生长素受体 SlTIR1 和 SlAFB6 直接相互作用。此外，E 在蛋白结构域 II 的突变和生长素或蛋白酶体活性的抑制下稳定，这意味着 E 受到生长素介导的降解。在 e 突变体中，DR5 信号扩展到包括完整的叶片边缘，并且叶片特异性过表达稳定形式的 E 抑制了 DR5 信号和叶片扩张。GOB 活性的遗传操作改变了 DR5 信号的分布，生长素运输或活性的抑制抑制了 GOB 过表达表型，表明生长素介导 GOB 调节的叶片模式形成。尽管单个 e 或 gob 突变体的叶片仅发育出初级小叶，但 E 和 GOB 的下调导致小叶起始完全被取消，并且叶片边缘出现强烈的 DR5 信号。这些结果表明，E 和 GOB 通过部分冗余途径调节生长素反应和小叶形态发生，并且适当的小叶起始和分离需要叶片生长区域和相邻生长受抑制区域之间的独特边界。
