Lai Yuqiu, Feng Zhihang, Lin Xianyong, Shi Weiming, Busch Wolfgang, Li Baohai
MOE Key Laboratory of Environment Remediation and Ecological Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, China.
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, 71 East Beijing Road, Nanjing, 210008, China.
New Phytol. 2025 Aug;247(3):1290-1307. doi: 10.1111/nph.70279. Epub 2025 Jun 8.
Calcium (Ca), an essential macronutrient, is crucial for the growth of young plant tissues, including the formation of lateral roots (LRs) that originate from pericycle cells in the inner root. The Casparian strip (CS) serves as an apoplastic barrier in the root endodermis, optimizing nutrient transport and facilitating plant adaptation to various environments. This study demonstrates that the integrity of the CS regulates local Ca-dependent LR emergence by controlling the lignification of the overlying endodermal cells in Arabidopsis. In mutants with disrupted CS integrity and compensatory lignin deposition, plants require sufficient Ca to maintain auxin gradients and the morphology of LR primordia, thereby promoting LR primordia through the endodermis. Both piperonylic acid treatment and genetic evidence indicate that excessive lignification of the overlying endodermal cells significantly delays LR emergence under low-Ca conditions compared with sufficient Ca. The receptor-like kinase SGN3/GSO1 mediates this excessive lignification. Importantly, the function of the CS in LR emergence is independent of Ca translocation from roots to shoots and, consequently, shoot growth dynamics. Overall, our study highlights the direct involvement of CS integrity in modulating Ca-dependent LR emergence by controlling cell wall stiffness through the lignification of overlying endodermal cells.
钙（Ca）是一种必需的大量营养素，对幼嫩植物组织的生长至关重要，包括源自根内部中柱鞘细胞的侧根（LRs）的形成。凯氏带（CS）作为根内皮层中的质外体屏障，优化养分运输并促进植物对各种环境的适应。本研究表明，CS的完整性通过控制拟南芥中覆盖其上的内皮层细胞的木质化来调节局部钙依赖性LR的出现。在CS完整性被破坏且有补偿性木质素沉积的突变体中，植物需要足够的钙来维持生长素梯度和LR原基的形态，从而促进LR原基穿过内皮层。胡椒酸处理和遗传学证据均表明，与充足的钙相比，在低钙条件下，覆盖其上的内皮层细胞过度木质化会显著延迟LR的出现。类受体激酶SGN3/GSO1介导这种过度木质化。重要的是，CS在LR出现中的功能独立于钙从根到地上部的转运，因此也独立于地上部的生长动态。总体而言，我们的研究强调了CS完整性通过控制覆盖其上的内皮层细胞的木质化来调节细胞壁硬度，从而直接参与调节钙依赖性LR的出现。
