Characterization of the DOG1 and ABA molecular interplay in seed dormancy.

• Applicant: Guillaume Née, Ph.D.
• Subject Area: Plant Physiology ; Plant Biochemistry and Biophysics
• Term: from 2018 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 398017926

Germination time is a major determinant of plant fitness. Both the abscisic acid molecule (ABA) and the protein delay of Germination 1 (DOG1) are required to induce seed dormancy. While the ABA pathway is well characterized, the DOG1 pathway is far from being understood. Our report that DOG1 interacts with seed specific clade A PP2C of the ABA signalling and represses their action to control dormancy, significantly advanced the field of germination. The downstream molecular events, which are under the genuine control of the DOG1-PP2C module needs further investigation now. We performed an analysis of the dog1 mutant seed phosphoproteome and observed that the DOG1-PP2C module is not implied in the control of the ABA canonical pathway but of proteins aside the core signalling. We identified a promising candidate phosphorylation site in an unknown function protein family. We have strengthened our hypothesis that members from this family are important players in the DOG1 pathway. We showed that they specifically interact with the DOG1 controlled PP2C Aba Hypersensitive Germination1 (AHG1), control dormancy stricto sensu, and that the phosphorylated residue is implied in the association of these proteins with nuclear speckles, indicating that it is functionally relevant. In this project, we aim to investigate by genetic approaches the redundancy of the three most expressed members of this protein family in seeds, and their requirement for DOG1 to control dormancy. In addition, complementation assays will indicate the importance of the identified phosphorylated site for seed dormancy and AHG1 functions. Finally, using a combination of molecular methods and targeted proteomics, we will investigate the mechanistic determinants by which the DOG1-PP2C module influences the functions of our candidates to regulate seed dormancy.

• DFG Programme: Research Grants