PLoS Genetics：植物生长素空间分布和器官形态新发现

　　

作为植物发育调控最重要的激素，生长素的含量及其在器官中的分布（空间分布）决定了植物器官的形态建成、株型以及向重性反应等生物学进程。然而，目前对植物生长素在器官中空间分布的调控机制仍缺乏了解。

中科院植物研究所胡玉欣研究组以拟南芥为材料，通过研究功能获得及缺陷突变体，发现植物特有转录因子IDD14、IDD15和IDD16协同调控叶、花及茎形态建成和向重性反应（图A）。进一步研究发现，该IDDs亚家族成员直接调控了生长素的合成和运输基因的表达，改变生长素在植物器官内的分布，从而影响植物器官的形态建成和重力反应过程（图B、C）。这些研究结果揭示了植物生长素空间分布和器官形态建成调控的一个新机制。

相关研究成果已于9月5日在PLoS Genetics（2013，9（9）：e1003759.）在线发表。胡玉欣研究组助理研究员崔大勇为该论文的第一作者。

原文摘要：

The Arabidopsis IDD14, IDD15, and IDD16 Cooperatively Regulate Lateral Organ Morphogenesis and Gravitropism by Promoting Auxin Biosynthesis and Transport

The plant hormone auxin plays a critical role in regulating various aspects of plant growth and development, and the spatial accumulation of auxin within organs, which is primarily attributable to local auxin biosynthesis and polar transport, is largely responsible for lateral organ morphogenesis and the establishment of plant architecture. Here, we show that three Arabidopsis INDETERMINATE DOMAIN (IDD) transcription factors, IDD14, IDD15, and IDD16, cooperatively regulate auxin biosynthesis and transport and thus aerial organ morphogenesis and gravitropic responses. Gain-of-function of each IDD gene in Arabidopsis results in small and transversally down-curled leaves, whereas loss-of-function of these IDD genes causes pleiotropic phenotypes in aerial organs and defects in gravitropic responses, including altered leaf shape, flower development, fertility, and plant architecture. Further analyses indicate that these IDD genes regulate spatial auxin accumulation by directly targeting YUCCA5 (YUC5), TRYPTOPHAN AMINOTRANSFERASE of ARABIDOPSIS1 (TAA1), and PIN-FORMED1 (PIN1) to promote auxin biosynthesis and transport. Moreover, mutation or ectopic expression of YUC suppresses the organ morphogenic phenotype and partially restores the gravitropic responses in gain- or loss-of-function idd mutants, respectively. Taken together, our results reveal that a subfamily of IDD transcription factors plays a critical role in the regulation of spatial auxin accumulation, thereby controlling organ morphogenesis and gravitropic responses in plants.