[植物荷爾蒙] 細胞分裂素與生長素之間的調控 20191004 Developmental Cell

TRANSPORTER OF IBA1 Links Auxin and Cytokinin to Influence Root Architecture

Marta Michniewicz, Cheng-Hsun Ho, Tara A. Enders, Eric Floro, Suresh Damodaran, Lauren K. Gunther, Samantha K. Powers, Elizabeth M. Frick, Christopher N. Topp, Wolf B. Frommer, and Lucia C. Strader

SUMMARY

Developmental processes that control root system architecture are critical for soil exploration by plants, allowing for uptake of water and nutrients. Conversion of the auxin precursor indole-3-butyric acid (IBA) to active auxin (indole-3-acetic acid; IAA) modulates lateral root formation. However, mechanisms governing IBA-to-IAA conversion have yet to be elucidated. We identified TRANSPORTER OF IBA1 (TOB1) as a vacuolar IBA transporter that limits lateral root formation. Moreover, TOB1, which is transcriptionally regulated by the phytohormone cytokinin, is necessary for the ability of cytokinin to exert inhibitory effects on lateral root production. The increased production of lateral roots in tob1 mutants, TOB1 transport of IBA into the vacuole, and cytokinin-regulated TOB1 expression provide a mechanism linking cytokinin signaling and IBA contribution to the auxin pool to tune root system architecture.

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Transporter of IBA1 （IBA運輸蛋白1）連結了生長素與細胞分裂素來影響植物根部的結構

總結

調節植物根系整體結構的生長程序，對於植物在土壤中探索和攝取水分及養分而言相當的重要。將生長素前驅物IBA，轉化成有活性的生長素IAA，是一個調節側根的形成的程序。然而，掌控IBA轉化至IAA的機制，仍然未被闡明。我們鑑識出了一個在液泡膜上運輸IBA的運輸蛋白（TOB1），這個基因（突變）限制了側根的形成。此外，另一個植物荷爾蒙 - 細胞分裂素，控制了TOB1的轉錄。而這個轉錄的調控，在細胞分裂素控制植物側根生成的機制中，必要存在的調控。在tob1的突變植株中，側根的產生有所上升、以及TOB1將IBA運輸到液泡內，再加上細胞分裂素調控了TOB1的表現，這幾個要素連結了細胞分裂素的訊息傳導和IBA對於整體生長素總量的影響，最終可用來調節植物根系的結構。