Nitrate is an essential nutrient that drives plant root architecture, notably by adjusting the development of lateral roots (LR). This involves an intricate hormonal interplay, in which auxin is a key element. Protein farnesylation is a post-translational modification that has been for long associated with hormone biosynthesis and signaling. However, its involvement in the control of root architecture has not been described. Characterization of the root architecture of the Arabidopsis thaliana era1 (enhanced response to abscisic acid (ABA) 1) mutant, that is devoid of protein farnesyl-transferase (i.e. proteins are not farnesylated in this mutant), was performed in response to nitrate. While LRs are constitutively shorter in era1, the mutant develops a higher number of LRs under low KNO₃ compared to WT. In addition, era1 is more sensitive to auxin, cytokinins, ABA and brassinolide, phytohormones that participate in LR establishment. Quantitative RT-PCRs highlighted that, in era1, the expression of genes involved in auxin or ABA signaling pathways are significantly down- or up-regulated in response to nitrate. Additionally, three Arabidopsis mutants lacking known farnesylatable proteins involved in hormonal pathways, were characterized. Among them, the cyp85A2 (cytochrome P450 85A2, affected in brassinosteroids) mutant displayed a constitutive lower LR number while the ipt3 (isopentenyl transferase 3, affected in cytokinins) mutant lost the nitrate-dependent LR formation. Altogether our results support the involvement of protein farnesylation in the hormonal crosstalk that governs root architecture.

硝酸盐是驱动植物根系结构的必需营养素，特别是通过调节侧根 (LR) 的发育。这涉及错综复杂的激素相互作用，其中生长素是关键元素。蛋白质法尼基化是一种翻译后修饰，长期以来一直与激素生物合成和信号传导有关。然而，尚未描述其参与根架构的控制。对没有蛋白质法尼基转移酶（即蛋白质在该突变体中没有法尼基化）的拟南芥era1（对脱落酸（ABA）1的响应增强）突变体的根结构进行了表征，以响应硝酸盐。虽然 LR 在本构上更短在era1中，与WT 相比，该突变体在低KNO ₃下产生更多的LR 。此外，era1对生长素、细胞分裂素、ABA和芸苔素内酯等参与LR建立的植物激素更为敏感。定量 RT-PCR 强调，在era1中，参与生长素或 ABA 信号通路的基因的表达响应硝酸盐显着下调或上调。此外，三个拟南芥突变体缺乏已知的参与激素途径的可法尼基化蛋白，并进行了表征。其中，cyp85A2（细胞色素 P450 85A2，受油菜素类固醇影响）突变体显示出组成型较低的 LR 数，而ipt3（异戊烯基转移酶3，受细胞分裂素影响）突变体失去了硝酸盐依赖性 LR 形成。总之，我们的结果支持蛋白质法尼基化参与控制根结构的激素串扰。