Frank Manuel, Kaulfürst-Soboll Heidi, Fischer Kerstin, von Schaewen Antje
Molecular Physiology of Plants, Institute of Plant Biology and Biotechnology, University of Münster (WWU Münster), Münster, Germany.
Department of Molecular Biology and Genetics, Aarhus University, Aarhus C, Denmark.
Front Plant Sci. 2021 Feb 18;12:635714. doi: 10.3389/fpls.2021.635714. eCollection 2021.
Roots supply plants with nutrients and water, besides anchoring them in the soil. The primary root with its lateral roots constitutes the central skeleton of the root system. In particular, root hairs increase the root surface, which is critical for optimizing uptake efficiency. During root-cell growth and development, many proteins that are components of, e.g., the cell wall and plasma membrane are constitutively transported through the secretory system and become posttranslationally modified. Here, the best-studied posttranslational modification is protein N-glycosylation. While alterations in the attachment/modification of N-glycans within the ER lumen results in severe developmental defects, the impact of Golgi-localized complex N-glycan modification, particularly on root development, has not been studied in detail. We report that impairment of complex-type N-glycosylation results in a differential response to synthetic phytohormones with earlier and increased root-hair elongation. Application of either the cytokinin BAP, the auxin NAA, or the ethylene precursor ACC revealed an interaction of auxin with complex N-glycosylation during root-hair development. Especially in mutant seedlings, the early block of complex N-glycan formation resulted in an increased auxin sensitivity. RNA-seq experiments suggest that roots have permanently elevated nutrient-, hypoxia-, and defense-stress responses, which might be a consequence of the altered auxin responsiveness.
根为植物提供养分和水分，同时将它们固定在土壤中。主根及其侧根构成了根系的中心骨架。特别是根毛增加了根的表面积，这对于优化吸收效率至关重要。在根细胞生长和发育过程中，许多作为细胞壁和质膜等组成成分的蛋白质通过分泌系统持续运输，并发生翻译后修饰。在这里，研究得最透彻的翻译后修饰是蛋白质N-糖基化。虽然内质网腔内N-聚糖的连接/修饰改变会导致严重的发育缺陷，但高尔基体定位的复杂N-聚糖修饰的影响，特别是对根发育的影响，尚未得到详细研究。我们报告说，复杂型N-糖基化的损伤导致对合成植物激素的差异反应，根毛伸长更早且增加。应用细胞分裂素BAP、生长素NAA或乙烯前体ACC揭示了在根毛发育过程中生长素与复杂N-糖基化之间的相互作用。特别是在突变体幼苗中，复杂N-聚糖形成的早期阻断导致生长素敏感性增加。RNA测序实验表明，突变体根具有持续升高的养分、缺氧和防御应激反应，这可能是生长素反应性改变的结果。
