Neo-functionalization of a Teosinte branched 1 homologue mediates adaptations of upland rice

• Published in: Nature communications 2020-02, Vol.11 (1), p.725-13, Article 725
• Main Authors: Lyu, Jun, Huang, Liyu, Zhang, Shilai, Zhang, Yesheng, He, Weiming, Zeng, Peng, Zeng, Yan, Huang, Guangfu, Zhang, Jing, Ning, Min, Bao, Yachong, Zhao, Shilei, Fu, Qi, Wade, Len J., Chen, Hua, Wang, Wen, Hu, Fengyi
• Format: Article
• Language: English
• Subjects: 14/19; 14/35; 38/39; 45/23; 45/44; 45/77; 631/181/2806; 631/208/711; 631/449/2669; 631/61/447/8; Adaptation; Adaptation, Biological; Agricultural Irrigation; Apical dominance; Corn; Domestication; Evolution, Molecular; Gene Duplication; Gene expression; Gene Expression Regulation, Plant; Homology; Humanities and Social Sciences; multidisciplinary; Mutation; Nicotiana - genetics; Oryza - physiology; Plant Proteins - genetics; Plant Proteins - metabolism; Plants, Genetically Modified; Polymorphism, Single Nucleotide; Proteins; Reproduction (copying); Rice; Science; Science (multidisciplinary)
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-019-14264-1

The rice orthologue of maize domestication gene Teosinte branched 1 ( Tb1 ) affects tillering. But, unlike maize Tb1 gene, it was not selected during domestication. Here, we report that an OsTb1 duplicate gene ( OsTb2 ) has been artificially selected during upland rice adaptation and that natural variation in OsTb2 is associated with tiller number. Interestingly, transgenic rice overexpressing this gene shows increased rather than decreased tillering, suggesting that OsTb2 gains a regulatory effect opposite to that of OsTb1 following duplication. Functional analyses suggest that the OsTb2 protein positively regulates tillering by interacting with the homologous OsTb1 protein and counteracts the inhibitory effect of OsTb1 on tillering. We further characterize two functional variations within OsTb2 that regulate protein function and gene expression, respectively. These results not only present an example of neo-functionalization that generates an opposite function following duplication but also suggest that the Tb1 homologue has been selected in upland rice. A transposon insertion in the regulatory region of maize Tb1 gene leads to increased apical dominance and a reduction of tillering. Here, the authors showed that a duplicated rice Tb1 orthologue, OsTb2 , has gained a regulatory effect on tillering opposite that of OsTb1 during artificial selection only in upland japonica rice.