State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng 475004, China.
Academy for Advanced Interdisciplinary Studies, Henan University, Kaifeng 475004, China.
Plant Physiol. 2022 Aug 29;190(1):548-561. doi: 10.1093/plphys/kiac301.
Plant lateral roots (LRs) play vital roles in anchorage and uptake of water and nutrients. Here, we reveal that degradation of lariat intronic RNAs (lariRNAs) modulated by SICKLE (SIC) is required for LR development in Arabidopsis (Arabidopsis thaliana). Loss of SIC results in hyper-accumulation of lariRNAs and restricts the outgrowth of LR primordia, thereby reducing the number of emerged LRs. Decreasing accumulation of lariRNAs by over-expressing RNA debranching enzyme 1 (DBR1), a rate-limiting enzyme of lariRNA decay, restored LR defects in SIC-deficient plants. Mechanistically, SIC interacts with DBR1 and facilitates its nuclear accumulation, which is achieved through two functionally redundant regions (SIC1-244 and SIC252-319) for nuclear localization. Of the remaining amino acids in this region, six (SIC245-251) comprise a DBR1-interacting region while two (SICM246 and SICW251) are essential for DBR1-SIC interaction. Reducing lariRNAs restored microRNA (miRNA) levels and LR development in lariRNA hyper-accumulating plants, suggesting that these well-known regulators of LR development mainly function downstream of lariRNAs. Taken together, we propose that SIC acts as an enhancer of DBR1 nuclear accumulation by driving nuclear localization through direct interaction, thereby promoting lariRNA decay to fine-tune miRNA biogenesis and modulating LR development.
植物侧根（LRs）在锚定和吸收水和养分方面起着至关重要的作用。在这里，我们揭示了由 SICKLE（SIC）调节的套索内含子 RNA（lariRNA）的降解对于拟南芥（Arabidopsis thaliana）LR 发育是必需的。SIC 的缺失导致 lariRNA 的过度积累，并限制 LR 原基的生长，从而减少出现的 LR 数量。通过过表达 RNA 分支酶 1（DBR1）来减少 lariRNA 的积累，一种 lariRNA 降解的限速酶，恢复了 SIC 缺陷植物的 LR 缺陷。从机制上讲，SIC 与 DBR1 相互作用并促进其核积累，这是通过两个功能冗余区域（SIC1-244 和 SIC252-319）实现的，用于核定位。在该区域剩余的氨基酸中，六个（SIC245-251）组成 DBR1 相互作用区域，而两个（SICM246 和 SICW251）对于 DBR1-SIC 相互作用是必需的。减少 lariRNA 恢复了 miRNA（miRNA）水平和 lariRNA 积累植物的 LR 发育，表明这些众所周知的 LR 发育调节剂主要在 lariRNA 下游发挥作用。总之，我们提出 SIC 通过直接相互作用作为 DBR1 核积累的增强子发挥作用，从而促进 lariRNA 降解，以微调 miRNA 的生物发生并调节 LR 发育。
