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Loss of function of the IAA-glucose hydrolase gene TGW6 enhances rice grain weight and increases yield



Increases in the yield of rice, a staple crop for more than half of the global population, are imperative to support rapid population growth. Grain weight is a major determining factor of yield. Here, we report the cloning and functional analysis of THOUSAND-GRAIN WEIGHT 6 (TGW6), a gene from the Indian landrace rice Kasalath. TGW6 encodes a novel protein with indole-3-acetic acid (IAA)-glucose hydrolase activity. In sink organs, the Nipponbare tgw6 allele affects the timing of the transition from the syncytial to the cellular phase by controlling IAA supply and limiting cell number and grain length. Most notably, loss of function of the Kasalath allele enhances grain weight through pleiotropic effects on source organs and leads to significant yield increases. Our findings suggest that TGW6 may be useful for further improvements in yield characteristics in most cultivars.

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Figure 1: Positional cloning and expression pattern of TGW6.
Figure 2: Effect of TGW6 on sink development.
Figure 3: Haplotype network of the TGW6 gene and its effects on yield characteristics across cultivars.

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Gene Expression Omnibus

NCBI Reference Sequence

Referenced accessions

Protein Data Bank


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We thank T. Meshi for helpful and important suggestions, Y. Shimoda and A. Miyamoto for help with experiments, T. Yanai and S. Yoshimizu for rice growth, K. Shimamoto (Nara Institute of Science and Technology) for providing the pANDA vector, K. Toshimitsu (Japan International Cooperation Agency) for providing seeds of NERICA and T. Kobayakawa for helpful discussions. The wild rice accessions used in this study were distributed from the National Institute of Genetics supported by the National Bioresource Project, Ministry of Education, Culture, Sports, Science and Technology, Japan. This work was supported by grants from the Bio Cosmos Program and Genomics for Agricultural Innovation (QTL-4007), Ministry of Agriculture, Forestry and Fisheries of Japan.

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Authors and Affiliations



K.I. conceived the research project, designed experiments and wrote the manuscript with help from N. Hirotsu, Y.M. and E.K. K.I., N. Hirotsu and Y.M. carried out field phenotyping, genetics, gene cloning and functional and molecular evolution experiments and analyzed the data. N. Hara helped with in situ hybridization, and H.O. assisted in transformation. N.M. helped with phenotyping, genotyping and gene cloning. T.K. and K.U. helped with field work, and B.S., A.O. and H.M. quantified IAA content. E.K. performed structure analysis.

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Correspondence to Ken Ishimaru.

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Ishimaru, K., Hirotsu, N., Madoka, Y. et al. Loss of function of the IAA-glucose hydrolase gene TGW6 enhances rice grain weight and increases yield. Nat Genet 45, 707–711 (2013).

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