Graduate School of Green-Bio Science & Crop Biotech Institute, Kyung Hee University, Yongin 17104, Republic of Korea.
Strategic Innovation Platform, International Rice Research Institute, Metro Manila, Philippines.
J Adv Res. 2022 Dec;42:69-81. doi: 10.1016/j.jare.2022.05.007. Epub 2022 May 21.
Root development is a fundamental process that supports plant survival and crop productivity. One of the essential factors to consider when developing biotechnology crops is the selection of a promoter that can optimize the spatial-temporal expression of introduced genes. However, there are insufficient cases of suitable promoters in crop plants, including rice.
This study aimed to verify the usefulness of a new rice root-preferred promoter to optimize the function of a target gene with root-preferred expression in rice.
osrns1 mutant had defects in root development based on T-DNA insertional mutant screening and CRISPR technology. To optimize the function of OsRNS1, we generated OsRNS1-overexpression plants under two different promoters: a whole-plant expression promoter and a novel root-preferred expression promoter. Root growth, yield-related agronomic traits, RNA-seq, and reactive oxygen species (ROS) accumulation were analyzed for comparison.
OsRNS1 was found to be involved in root development through T-DNA insertional mutant analysis and gene editing mutant analysis. To understand the gain of function of OsRNS1, pUbi1::OsRNS1 was generated for the whole-plant expression, and both root growth defects and overall growth defects were found. To overcome this problem, a root-preferential overexpression line using Os1-CysPrxB promoter (Per) was generated and showed an increase in root length, plant height, and grain yield compared to wild-type (WT). RNA-seq analysis revealed that the response to oxidative stress-related genes was significantly up-regulated in both overexpression lines but was more obvious in pPer::OsRNS1. Furthermore, ROS levels in the roots were drastically decreased in pPer::OsRNS1 but were increased in the osrns1 mutants compared to WT.
The results demonstrated that the use of a root-preferred promoter effectively optimizes the function of OsRNS1 and is a useful strategy for improving root-related agronomic traits as well as ROS regulation.
根发育是支持植物生存和作物生产力的基本过程。在开发生物技术作物时，需要考虑的一个重要因素是选择能够优化引入基因时空表达的启动子。然而，包括水稻在内的作物中，合适的启动子并不多。
本研究旨在验证一种新的水稻根特异启动子在优化具有根特异表达的靶基因在水稻中的功能方面的有用性。
基于 T-DNA 插入突变体筛选和 CRISPR 技术，osrns1 突变体在根发育方面存在缺陷。为了优化 OsRNS1 的功能，我们在两种不同的启动子下生成了 OsRNS1 过表达植株：一种是全株表达启动子，另一种是新的根特异表达启动子。对根生长、与产量相关的农艺性状、RNA-seq 和活性氧（ROS）积累进行了分析比较。
通过 T-DNA 插入突变体分析和基因编辑突变体分析，发现 OsRNS1 参与根发育。为了了解 OsRNS1 的功能获得，生成了 pUbi1::OsRNS1 用于全株表达，发现根生长缺陷和整体生长缺陷。为了克服这个问题，利用 Os1-CysPrxB 启动子（Per）生成了根特异过表达系，并显示出比野生型（WT）更长的根长、更高的株高和更高的产量。RNA-seq 分析显示，两种过表达系中与氧化应激相关基因的应答均显著上调，但 pPer::OsRNS1 中更为明显。此外，pPer::OsRNS1 中的根 ROS 水平明显降低，但 osrns1 突变体与 WT 相比则增加。
结果表明，使用根特异启动子可有效优化 OsRNS1 的功能，是改善根相关农艺性状和 ROS 调节的有效策略。
