Zhang et al. show that GIF1 regulates the determinacy of meristems and controls tassel architecture in maize. The Plant Cell (2018). https://doi.org/10.1105/tpc.17.00791
Background: Plant architecture results from a balance of indeterminate and determinate cell fates. Cells with indeterminate fates are located in meristems. The shoot apical meristem is an indeterminate tissue, initiating primordia indefinitely. Floral meristems are determinate structures that terminate after the production of floral organs. Most developmental mutants identified so far affect one or two parts of the phytomer and rarely play a role in multiple aspects of shoot architecture. We identified mutants of maize gif1 that affects multiple meristems, but in different ways.
Question: We want to know how gif1 regulates the determinacy of meristems and controls tassel architecture. We tested this by cloning gif1 from two independent mutants, and analysing gif1 expression and identifying direct targets of GIF1.
Finding: gif1 expresses in actively dividing cells of shoot apical and inflorescence meristems, showing an expression pattern overlapped with that of ramosa2 (ra2) and unbranched3 (ub3) in inflorescences. Mutation of gif1 leads to a fasciated tassel with reduced branches which is explained by GIF1 direct targeting ub3.
Next steps: We are working to reveal how GIF1 differentially regulates branching of both tassel and ear, and how GIF1 controls the fertility of male and female flowers.
Dan Zhang, Wei Sun, Renee Singh, Yuanyuan Zheng, Zheng Cao, Manfei Li, China Lunde, Sarah Hake, Zuxin Zhang. (2018) GRF-interacting factor1 (gif1) regulates shoot architecture and meristem determinacy in maize. The Plant Cell 30: 360-374; DOI: https://doi.org/10.1105/tpc.17.00791