J Integr Plant Biol. ›› 2021, Vol. 63 ›› Issue (5): 865-877.DOI: 10.1111/jipb.13050

Special Issue: Development

• Cell and Developmental Biology • Previous Articles     Next Articles

BRITTLE PLANT1 is required for normal cell wall composition and mechanical strength in rice

Yuanyan Zhang1†, Yihua Wang1†, Chunming Wang1†, Carsten Rautengarten2, Erchao Duan1, Jianping Zhu1, Xiaopin Zhu1, Jie Lei1, Chao Peng1, Yunlong Wang1, Xuan Teng1, Yunlu Tian1, Xi Liu1, Joshua L. Heazlewood2, Aimin Wu3 and Jianmin Wan1,4*   

  1. 1State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing 210095, China
    2School of BioSciences, The University of Melbourne, Parkville, Victoria 3010, Australia
    3Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architectures, South China Agricultural University, Guangzhou 510642, China
    4National Key Facility for Crop Resources and Genetic Improvement, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China

    These authors contributed equally to this work.
    *Correspondence: Jianmin Wan (wanjm@njau.edu.cn) or wanjianmin@caas.cn
  • Received:2020-11-17 Accepted:2020-12-04 Online:2020-12-08 Published:2021-05-01

Abstract: A series of nucleotide sugar interconversion enzymes (NSEs) generate the activated sugar donors required for biosynthesis of cell wall matrix polysaccharides and glycoproteins. UDP‐glucose 4‐epimerases (UGEs) are NSEs that function in the interconversion of UDP‐glucose (UDP‐Glc) and UDP‐galactose (UDP‐Gal). The roles of UDP‐glucose 4‐epimerases in monocots remain unclear due to redundancy in the pathways. Here, we report a brittle plant (bp1) rice mutant that exhibits brittle leaves and culms at all growth stages. The mutant culms had reduced levels of rhamnogalacturonan I, homogalacturonan, and arabinogalactan proteins. Moreover, the mutant had altered contents of uronic acids, neutral noncellulosic monosaccharides, and cellulose. Map‐based cloning demonstrated that OsBP1 encodes a UDP‐glucose 4‐epimerase (OsUGE2), a cytosolic protein. We also show that BP1 can form homo‐ and hetero‐protein complexes with other UGE family members and with UDP‐galactose transporters 2 (OsUGT2) and 3 (OsUGT3), which may facilitate the channeling of Gal to polysaccharides and proteoglycans. Our results demonstrate that BP1 participates in regulating the sugar composition and structure of rice cell walls.

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