Overexpression of OsSnRK1a through a green tissue-specific promoter improves rice yield by accelerating sheath-to-panicle transport of nonstructural carbohydrates and increasing leaf photosynthesis

Yuxiang Hu; Yan Lin; Yongqing Xia; Xuemei Xu; Ziteng Wang; Xiran Cui; Lin Han; Jiaoyang Li; Rongtao Zhang; Yanfeng Ding; Lin Chen

doi:10.1016/j.plaphy.2023.108048

Overexpression of OsSnRK1a through a green tissue-specific promoter improves rice yield by accelerating sheath-to-panicle transport of nonstructural carbohydrates and increasing leaf photosynthesis

Plant Physiol Biochem. 2023 Oct:203:108048. doi: 10.1016/j.plaphy.2023.108048. Epub 2023 Sep 21.

Authors

Yuxiang Hu¹, Yan Lin¹, Yongqing Xia¹, Xuemei Xu¹, Ziteng Wang¹, Xiran Cui², Lin Han², Jiaoyang Li², Rongtao Zhang², Yanfeng Ding³, Lin Chen⁴

Affiliations

¹ College of Agriculture, Nanjing Agricultural University, Nanjing, China; Key Laboratory of Crop Physiology & Ecology in Southern China, Ministry of Agricultural University, Nanjing, China.
² College of Agriculture, Nanjing Agricultural University, Nanjing, China.
³ College of Agriculture, Nanjing Agricultural University, Nanjing, China; Key Laboratory of Crop Physiology & Ecology in Southern China, Ministry of Agricultural University, Nanjing, China; Collaborative Innovation Center for Modern Crop Production co-sponsored by Province and Ministry, Nanjing, China.
⁴ College of Agriculture, Nanjing Agricultural University, Nanjing, China; Key Laboratory of Crop Physiology & Ecology in Southern China, Ministry of Agricultural University, Nanjing, China; Collaborative Innovation Center for Modern Crop Production co-sponsored by Province and Ministry, Nanjing, China. Electronic address: linchen@njau.edu.cn.

PMID: 37757719
DOI: 10.1016/j.plaphy.2023.108048

Abstract

The redistribution of nonstructural carbohydrates (NSCs) in rice (Oryza sativa) sheaths contributes greatly to grain filling. Sucrose nonfermenting-1-related protein kinase 1 (SnRK1) regulates sheath-to-panicle transport of NSCs during rice grain filling; however, it is unknown whether elevated activity of SnRK1 in sheaths improves NSC transport and grain filling. Expression of OsSnRK1a is mainly responsible for regulating SnRK1 activity in rice sheaths. Analysis of transgenic rice plants containing the OsSnRK1a promoter::GUS construct indicated that OsSnRK1a is widely expressed in rice. Notably, OsSnRK1a is highly expressed in mesophyll cells of sheaths. Therefore, a green tissue promoter specifically expressed in sheaths and leaf parenchyma cells and phloem tissue was used to over-express OsSnRK1a in japonica rice. The transgenic lines exhibited increased SnRK1a expression and SnRK1 activity in sheaths. The NSC and starch in the transgenic lines and WT all showed accumulation before heading and during the early-filling stage, and declining at the peak filling stage. But the starch and NSC content in transgenic lines was lower than that of WT. Moreover, the transgenic lines showed lower sucrose contents and higher sucrose efflux rates. The accelerated sheath NSC transport improved grain filling, and stimulated panicle development in transgenic lines. SnRK1a expression and SnRK1 activity were also increased in the leaves of transgenic lines, which improved leaf photosynthetic activity and contributed to optimal grain filling and panicle development. These results verify the promotion of high SnRK1 activity in sheath NSC transport, and also provide a new approach to improving sheath NSC transport and rice yield.

Keywords: Green tissue-specific promoter; NSC transport; Rice grain filling; Sheath; SnRK1.