J Integr Plant Biol. ›› 2018, Vol. 60 ›› Issue (11): 1097-1118.DOI: 10.1111/jipb.12692

Special Issue: Rice Genomics and Agriculture

• Metabolism and Biochemistry • Previous Articles    

OsPKpα1 encodes a plastidic pyruvate kinase that affects starch biosynthesis in the rice endosperm

Yue Cai1†, Wenwei Zhang1†, Jie Jin1, Xiaoming Yang1, Xiaoman You1, Haigang Yan1, Liang Wang1, Jie Chen1, Jiahuan Xu1, Weiwei Chen1, Xingang Chen1, Jing Ma1, Xiaojie Tang1, Fei Kong1, Xiaopin Zhu1, Guoxiang Wang1, Ling Jiang1, William Terzaghi3, Chunming Wang1 and Jianmin Wan1,2**   

  1. 1State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing 210095, China
    2National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing 100081, China
    3Department of Biology, Wilkes University, Wilkes-Barre, PA 18766, USA

    ?These authors contributed equally to this work.
    **Correspondence:

    Email: Jianmin Wan (wanjm@njau.edu.cn or wanjianmin@caas.cn)
  • Received:2018-03-14 Accepted:2018-06-25 Online:2018-06-26 Published:2018-11-01

Abstract:

Pyruvate kinase (PK) is a key enzyme in glycolysis and carbon metabolism. Here, we isolated a rice (Oryza sativa) mutant, w59, with a white-core floury endosperm. Map-based cloning of w59 identified a mutation in OsPKpα1, which encodes a plastidic isoform of PK (PKp). OsPKpα1 localizes to the amyloplast stroma in the developing endosperm, and the mutation of OsPKpα1 in w59 decreases the plastidic PK activity, resulting in dramatic changes to the lipid biosynthesis in seeds. The w59 grains were also characterized by a marked decrease in starch content. Consistent with a decrease in number and size of the w59 amyloplasts, large empty spaces were observed in the central region of the w59 endosperm, at the early grain-filling stage. Moreover, a phylogenetic analysis revealed four potential rice isoforms of OsPKp. We validated the in vitro PK activity of these OsPKps through reconstituting active PKp complexes derived from inactive individual OsPKps, revealing the heteromeric structure of rice PKps, which was further confirmed using a protein-protein interaction analysis. These findings suggest a functional connection between lipid and starch synthesis in rice endosperm amyloplasts.

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