Cytokinin signalling inhibitory fields provide robustness to phyllotaxis

摘要

How biological systems generate reproducible patterns with high precision is a central question in science. The shoot apical meristem (SAM), a specialized tissue producing plant aerial organs, is a developmental system of choice to address this question. Organs are periodically initiated at the SAM at specific spatial positions and this spatiotemporal pattern defines phyllotaxis. Accumulation of the plant hormone auxin triggers organ initiation, whereas auxin depletion around organs generates inhibitory fields that are thought to be sufficient to maintain these patterns and their dynamics. Here we show that another type of hormone-based inhibitory fields, generated directly downstream of auxin by intercellular movement of the cytokinin signalling inhibitor ARABIDOPSIS HISTIDINE PHOSPHOTRANSFER PROTEIN 6 (AHP6), is involved in regulating phyllotactic patterns. We demonstrate that AHP6-based fields establish patterns of cytokinin signalling in the meristem that contribute to the robustness of phyllotaxis by imposing a temporal sequence on organ initiation. Our findings indicate that not one but two distinct hormone-based fields may be required for achieving temporal precision during formation of reiterative structures at the SAM, thus indicating an original mechanism for providing robustness to a dynamic developmental system.%器官在植物茎周围的规则排列被称为“叶序”rn(phyllotaxis)。植物激素“茁长素”的积累触rn发器官开始形成，而器官周围“茁长素”耗尽rn会产生“抑制场”，后者被认为足以维持这些rn模式。在这项研究中，Teva Vemoux及同事rn发现，该过程还可能涉及第二种基于激素的rn”场”。他们发现，“苗端”内细胞分裂素抑制rn因子AHP6在细胞间的运动会在“茁长素”的下rn游产生一些“场”，这些“场”会在分裂组织中rn产生细胞分裂素信号作用活动的空间模式，从rn而使得“叶序”具有稳定性。