Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, Vienna (BOKU), Muthgasse 18, 1190, Vienna, Austria.
Department of Biology, Stanford University, 260 Panama Street, Stanford, CA, 94305, USA.
Nat Commun. 2019 Aug 6;10(1):3540. doi: 10.1038/s41467-019-11483-4.
Directional organ growth allows the plant root system to strategically cover its surroundings. Intercellular auxin transport is aligned with the gravity vector in the primary root tips, facilitating downward organ bending at the lower root flank. Here we show that cytokinin signaling functions as a lateral root specific anti-gravitropic component, promoting the radial distribution of the root system. We performed a genome-wide association study and reveal that signal peptide processing of Cytokinin Oxidase 2 (CKX2) affects its enzymatic activity and, thereby, determines the degradation of cytokinins in natural Arabidopsis thaliana accessions. Cytokinin signaling interferes with growth at the upper lateral root flank and thereby prevents downward bending. Our interdisciplinary approach proposes that two phytohormonal cues at opposite organ flanks counterbalance each other's negative impact on growth, suppressing organ growth towards gravity and allow for radial expansion of the root system.
定向器官生长使植物根系能够战略性地覆盖其周围环境。细胞间生长素的运输与主根尖端的重力矢量一致，促进了下根侧翼的器官向下弯曲。在这里，我们表明细胞分裂素信号作为侧根特有的抗向重力成分起作用，促进了根系的径向分布。我们进行了全基因组关联研究，揭示了细胞分裂素氧化酶 2（CKX2）的信号肽处理影响其酶活性，从而决定了天然拟南芥品系中细胞分裂素的降解。细胞分裂素信号干扰上侧根侧翼的生长，从而防止向下弯曲。我们的跨学科方法表明，在相反的器官侧翼的两种植物激素线索相互抵消彼此对生长的负面影响，抑制器官向重力生长，允许根系的径向扩展。
