一个世纪之前，达尔文描述了根向重性对植物生长的重要性，根系在土壤中的分布直接影响植物对营养和水分的吸收与利用。植物激素生长素具有较强的流动性，运输载体蛋白PIN对调控生长素在植物体内的运输过程起到重要作用。

中国科学院植物研究所研究员乐捷研究组的最新研究结果表明，拟南芥转录因子FOUR LIPS（FLP）和MYB88协同作用，控制主根和侧根根尖感重细胞中PIN3 和PIN7 基因的时空特异表达；PIN3 和PIN7 通过调整生长素在根两侧的定向运输和分布，动态地改变根对重力的响应角度，直接参与了根系重力形态建成。

该研究成果首次证明生长素运输载体PIN蛋白所参与的重力响应受到多个转录因子精细的动态调控，为进一步了解植物在长期进化过程中为适应重力环境所建立的感重性及其信号调控网络提供了新的线索。

该研究成果于11月18日在《自然·通讯》（Nature Communications）期刊上发表。乐捷研究组博士研究生王宏哲为论文第一作者。此外，乐捷参加的另一篇关于PIN3 调控侧根发生机制的合作论文也在同期发表。研究得到了国家重点基础研究发展计划和国家自然科学基金的资助。（来源：中国科学院植物研究所）

Transcriptional regulation of PIN genes by FOUR LIPS and MYB88 during Arabidopsis root gravitropism

Abstract  PIN proteins are auxin export carriers that direct intercellular auxin flow and in turn regulate many aspects of plant growth and development including responses to environmental changes. TheArabidopsis R2R3-MYB transcription factor FOUR LIPS (FLP) and its paralogue MYB88 regulate terminal divisions during stomatal development, as well as female reproductive development and stress responses. Here we show that FLP and MYB88 act redundantly but differentially in regulating the transcription of PIN3 and PIN7 in gravity-sensing cells of primary and lateral roots. On the one hand, FLP is involved in responses to gravity stimulation in primary roots, whereas on the other, FLP and MYB88 function complementarily in establishing the gravitropic set-point angles of lateral roots. Our results support a model in which FLP and MYB88 expression specifically determines the temporal-spatial patterns of PIN3 and PIN7 transcription that are closely associated with their preferential functions during root responses to gravity.

原文链接：http://www.nature.com/ncomms/2015/151118/ncomms9822/full/ncomms9822.html

A coherent transcriptional feed-forward motif model for mediating auxin-sensitive PIN3expression during lateral root development

Abstract  Multiple plant developmental processes, such as lateral root development, depend on auxin distribution patterns that are in part generated by the PIN-formed family of auxin-efflux transporters. Here we propose that AUXIN RESPONSE FACTOR7 (ARF7) and the ARF7-regulated FOUR LIPS/MYB124 (FLP) transcription factors jointly form a coherent feed-forward motif that mediates the auxin-responsive PIN3 transcription in planta to steer the early steps of lateral root formation. This regulatory mechanism might endow the PIN3 circuitry with a temporal ‘memory’ of auxin stimuli, potentially maintaining and enhancing the robustness of the auxin flux directionality during lateral root development. The cooperative action between canonical auxin signalling and other transcription factors might constitute a general mechanism by which transcriptional auxin-sensitivity can be regulated at a tissue-specific level.

原文链接：http://www.nature.com/ncomms/2015/151118/ncomms9821/full/ncomms9821.html