The Endosperm-Specific Expression of YUCCA Genes Enhances Rice Grain Filling
  • Huijun Jiang1,#, Kaien Zhai3,#, Xiaofan Ye3,#, Tianwei Hu2, Jieming Jiang4, Xiaoqiu Dong1, Weihuai Pan1, Jianwei Pan2, Jianxin Shou1,*
1 College of Life Sciences, Shaoxing University, Shaoxing, 312000, China
2 College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua, 321004, China
3 School of Life Sciences, Lanzhou University, Lanzhou, 730000, China
4 School of Life Science, South China Normal University, Guangzhou, 510631, China
* Corresponding Author: Jianxin Shou. Email: jxshou@126.com
# These authors contributed equally to this work
(This article belongs to this Special Issue:High-Yield Rice Physiology & Genetics)
Received 16 January 2022; Accepted 11 April 2022 ; Published online 09 June 2022
Abstract
Grain filling is a crucial process that affects yield in rice (Oryza sativa L.). Auxin biosynthesis and signaling are closely related to rice yield; therefore, it is important to understand the effects of auxin biosynthesis on rice grain filling to improve crop yield. In this study, we used physiological and molecular strategies to identify the roles of auxin in rice grain filling. Exogenous application of auxin (IAA) or auxin analogues (2, 4-D) to young spikelets and flag leaves improved the seed-setting rate and yield per spike. Furthermore, real-time quantitative PCR assays confirmed that nine members of the OsYUCCA family of auxin biosynthetic genes were upregulated during grain filling, implication that auxin biosynthesis plays a major role in grain development. The specific expression of either Arabidopsis AtYUCCA1 or OsYUCCA2 in the endosperm or leaves resulted in increased expression of OsIAA genes and auxin content of seeds, as well as increased grain filling and seed-setting rate. This result establishes that the auxin content in grains and leaves is important for grain development. Our findings further highlight the potential applications for improving rice yield by elevating targeted gene expression in specific tissues.
Keywords
Auxin content; grain filling; IAA biosynthesis; rice; seed-setting rate; YUCCA genes