Bellande Kevin, Roujol David, Chourré Josiane, Le Gall Sophie, Martinez Yves, Jauneau Alain, Arico Denise, Mithöfer Axel, Burlat Vincent, Jamet Elisabeth, Canut Hervé
Laboratoire de Recherche en Sciences Végétales, Université de Toulouse, CNRS, UPS, Toulouse INP, F-31320, Auzeville-Tolosane, France.
Laboratory of Cell and Molecular Biology, Institute of Biology, University of Neuchâtel, Rue Emile Argand 11, CH-2000 Neuchâtel, Switzerland and IPSiM, University of Montpellier, CNRS, INRAE, Institut Agro, Montpellier, France.
J Exp Bot. 2025 Apr 9;76(6):1718-1734. doi: 10.1093/jxb/erae520.
Assembling and remodelling the cell wall is essential for plant development. Cell wall dynamics are controlled by cell wall proteins, polysaccharide biosynthesis, and a variety of sensor and receptor systems. LecRK-I.9, an Arabidopsis thaliana plasma membrane-localized lectin receptor kinase, was previously shown to be involved in cell wall-plasma membrane contacts and to play roles in plant-pathogen interactions, but until now its role in development was not known. LecRK-I.9 is transcribed at a high level in root tissues including the pericycle. Comparative transcript profiling of a loss-of-function mutant versus the wild type identified LecRK-I.9 as a regulator of cell wall metabolism. Consistently, lecrk-I.9 mutants displayed an increased pectin methylesterification level correlated with decreased pectin methylesterase and increased polygalacturonase activities. Also, LecRK-I.9 negatively impacted lateral root development through the direct or indirect regulation of genes encoding (i) cell wall remodelling proteins during early events of lateral root initiation, and (ii) cell wall signalling peptides (CLE2 and CLE4) repressing lateral root emergence and growth. Furthermore, low nitrate reduced LecRK-I.9 expression in roots, particularly in the lateral root emergence zone: even in these conditions, the control of CLE2 and CLE4 expression is maintained. Altogether, the results show that LecRK-I.9 is a key player in negatively regulating both pre-branch site formation and lateral root emergence.
组装和重塑细胞壁对植物发育至关重要。细胞壁动态受细胞壁蛋白、多糖生物合成以及多种传感和受体系统的控制。凝集素受体激酶LecRK-I.9定位于拟南芥质膜，先前已证明其参与细胞壁与质膜的接触，并在植物与病原体的相互作用中发挥作用，但迄今为止其在发育中的作用尚不清楚。LecRK-I.9在包括中柱鞘在内的根组织中高水平转录。对功能缺失突变体与野生型进行比较转录谱分析，确定LecRK-I.9为细胞壁代谢的调节因子。一致地，lecrk-I.9突变体的果胶甲酯化水平增加，这与果胶甲酯酶活性降低和多聚半乳糖醛酸酶活性增加相关。此外，LecRK-I.9通过直接或间接调节以下基因对侧根发育产生负面影响：（i）在侧根起始早期事件中编码细胞壁重塑蛋白的基因，以及（ii）抑制侧根出现和生长的细胞壁信号肽（CLE2和CLE4）。此外，低硝酸盐会降低根中LecRK-I.9的表达，特别是在侧根出现区域：即使在这些条件下，对CLE2和CLE4表达的控制仍得以维持。总之，结果表明LecRK-I.9是负调控分支前位点形成和侧根出现的关键因子。
