<i>SMALL AND ROUND GRAIN</i> is involved in the brassinosteroid signaling pathway which regulates grain size in rice

Grain size is a key determinant of 1,000-grain weight, one of three factors determining grain yield. However, the complete regulatory network controlling grain size has not been fully clarified. Here, we identified a rice mutant, named small and round grain (srg) that exhibits semi-dwarf stature and small grain size. Cytological analysis showed that cell length and number of spikelet epidermal cells of the srg mutant are reduced, indicating that SRG controls grain size by promoting cell elongation and increasing cell number. SRG encodes a kinesin belonging to the kinesin-1 subfamily and is extensively expressed in different plant tissues with relatively high expression in young panicles. SRG protein is mainly located in the nucleus and cell membrane. Expression of the SRG gene was induced by brassinolide through the brassinosteroid (BR) responsive factor OsWRKY53 and SRG protein was phosphorylated by BR-activated kinase OsBSK3 to prevent its degradation. In addition, microtubule (MT) morphology was abnormal and disordered in the srg and cr-1 mutants. These findings suggest that BR likely stabilizes orderly assembly and arrangement of MTs by stabilizing SRG proteins, thus promoting grain size. SRG overexpression lines produced more tillers and significantly larger and heavier grains to increase 1,000-grain weight, suggesting that SRG has potential to increase grain yield. Our study indicated that SRG is a new BR responsive factor and BR might regulate grain size by influencing the expression of SRG.

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Publication Details

Journal
Journal of Integrative Plant Biology
Published
2025-02-12
DOI
https://doi.org/10.1111/jipb.13861
Citations
6
Primary Topic
Plant Molecular Biology Research
Type
article
Field-Weighted Citation Impact
10.50

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article

SMALL AND ROUND GRAIN is involved in the brassinosteroid signaling pathway which regulates grain size in rice

Thanhliem Nguyen, Changling Mou, Hongmin Wu, F. Zhang et al.
6 citations
Journal of Integrative Plant Biology
Plant Molecular Biology Research
10.50
article

SMALL AND ROUND GRAIN is involved in the brassinosteroid signaling pathway which regulates grain size in rice

Thanhliem Nguyen, Changling Mou, Hongmin Wu, F. Zhang, Sheng Luo, Miao Feng, Zhijun Cheng, Xiuping Guo, Ling Jiang, Shijia Liu, Rong Miao, Qixian Hao, Tengfei Ma, Jie Lan, Jianmin Wan, Qibing Lin, Chunlei Zhou, Hai Zheng, Yunshuai Huang, Penghui Cao
article en
6 citations

Abstract

Grain size is a key determinant of 1,000-grain weight, one of three factors determining grain yield. However, the complete regulatory network controlling grain size has not been fully clarified. Here, we identified a rice mutant, named small and round grain (srg) that exhibits semi-dwarf stature and small grain size. Cytological analysis showed that cell length and number of spikelet epidermal cells of the srg mutant are reduced, indicating that SRG controls grain size by promoting cell elongation and increasing cell number. SRG encodes a kinesin belonging to the kinesin-1 subfamily and is extensively expressed in different plant tissues with relatively high expression in young panicles. SRG protein is mainly located in the nucleus and cell membrane. Expression of the SRG gene was induced by brassinolide through the brassinosteroid (BR) responsive factor OsWRKY53 and SRG protein was phosphorylated by BR-activated kinase OsBSK3 to prevent its degradation. In addition, microtubule (MT) morphology was abnormal and disordered in the srg and cr-1 mutants. These findings suggest that BR likely stabilizes orderly assembly and arrangement of MTs by stabilizing SRG proteins, thus promoting grain size. SRG overexpression lines produced more tillers and significantly larger and heavier grains to increase 1,000-grain weight, suggesting that SRG has potential to increase grain yield. Our study indicated that SRG is a new BR responsive factor and BR might regulate grain size by influencing the expression of SRG.

Journal of Integrative Plant BiologyVol. 67(5)
Nanjing Agricultural University (CN), Suzhou Academy of Agricultural Sciences (CN), Quy Nhon University (VN), Chinese Academy of Agricultural Sciences (CN), Institute of Crop Sciences (CN)
National Natural Science Foundation of China, Chinese Academy of Sciences, Kyung Hee University, Government of Jiangsu Province, Ministry of Agriculture and Rural Affairs of the People's Republic of China, Jiangsu Collaborative Innovation Center for Modern Crop Production, National Key Research and Development Program of China, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences
Life in Land
Openalex Percentile: Top 2%
Plant Molecular Biology Research
10.50
DOIOpen Access PDFOpenAlex
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