Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, CP 58030 Morelia, Michoacán, Mexico.
Proc Natl Acad Sci U S A. 2011 Apr 26;108(17):7253-8. doi: 10.1073/pnas.1006740108. Epub 2011 Apr 11.
Microorganisms and their hosts communicate with each other through an array of signals. The plant hormone auxin (indole-3-acetic acid; IAA) is central in many aspects of plant development. Cyclodipeptides and their derivative diketopiperazines (DKPs) constitute a large class of small molecules synthesized by microorganisms with diverse and noteworthy activities. Here, we present genetic, chemical, and plant-growth data showing that in Pseudomonas aeruginosa, the LasI quorum-sensing (QS) system controls the production of three DKPs--namely, cyclo(L-Pro-L-Val), cyclo(L-Pro-L-Phe), and cyclo(L-Pro-L-Tyr)--that are involved in plant growth promotion by this bacterium. Analysis of all three bacterial DKPs in Arabidopsis thaliana seedlings provided detailed information indicative of an auxin-like activity, based on their efficacy at modulating root architecture, activation of auxin-regulated gene expression, and response of auxin-signaling mutants tir1, tir1 afb2 afb3, arf7, arf19, and arf7arf19. The observation that QS-regulated bacterial production of DKPs modulates auxin signaling and plant growth promotion establishes an important function for DKPs mediating prokaryote/eukaryote transkingdom signaling.
微生物及其宿主通过一系列信号相互交流。植物激素生长素（吲哚-3-乙酸；IAA）在植物发育的许多方面都起着核心作用。环二肽及其衍生物二酮哌嗪（DKP）是由微生物合成的一大类具有多种显著活性的小分子。在这里，我们提供遗传、化学和植物生长数据，表明铜绿假单胞菌中的 LasI 群体感应（QS）系统控制三种 DKP 的产生——即环（L-脯氨酰-L-缬氨酸）、环（L-脯氨酰-L-苯丙氨酸）和环（L-脯氨酰-L-酪氨酸）——这些 DKP 参与了该细菌对植物生长的促进。对拟南芥幼苗中所有三种细菌 DKP 的分析，基于它们对调节根系结构、激活生长素调节基因表达以及对生长素信号突变体 tir1、tir1 afb2 afb3、arf7、arf19 和 arf7arf19 的响应的功效，提供了生长素样活性的详细信息。QS 调节细菌 DKP 产生从而调节生长素信号和植物生长促进的观察结果，确立了 DKP 介导原核生物/真核生物跨域信号传递的重要功能。
