The evolution of plants is characterized by whole-genome duplications, sometimes closely associated with the origin of large groups of species. The gamma (gamma) genome triplication occurred at the... Show moreThe evolution of plants is characterized by whole-genome duplications, sometimes closely associated with the origin of large groups of species. The gamma (gamma) genome triplication occurred at the origin of the core eudicots, which comprise similar to 75% of flowering plants. To better understand the impact of whole-genome duplication, we studied the protein interaction network of MADS domain transcription factors, which are key regulators of reproductive development. We reconstructed, synthesized, and tested the interactions of ancestral proteins immediately before and closely after the triplication and directly compared these ancestral networks to the extant networks of Arabidopsis thaliana and tomato (Solanum lycopersicum). We found that gamma expanded the MADS domain interaction network more strongly than subsequent genomic events. This event strongly rewired MADS domain interactions and allowed for the evolution of new functions and installed robustness through new redundancy. Despite extensive rewiring, the organization of the network was maintained through gamma. New interactions and protein retention compensated for its potentially destructive impact on network organization. Post gamma, the network evolved from an organization around the single hub SEP3 to a network organized around multiple hubs and well-connected proteins lost, rather than gained, interactions. The data provide a resource for comparative developmental biology in flowering plants. Show less
Huang, F.; Kemel Zago, M.; Abas, L.; Marion, A. van; Galvan-Ampudia, C.S.; Offringa, R. 2010
Abscisic acid (ABA) induces a rapid and transient mitogen-activated protein (MAP) kinase activation in barley aleurone protoplasts. MAP kinase activity, measured as myelin basic protein... Show moreAbscisic acid (ABA) induces a rapid and transient mitogen-activated protein (MAP) kinase activation in barley aleurone protoplasts. MAP kinase activity, measured as myelin basic protein phosphorylation by MAP kinase immunoprecipitates, increased after 1 min, peaked after 3 min, and decreased to basal levels after ~5 min of ABA treatment in vivo. Antibodies recognizing phosphorylated tyrosine residues precipitate with myelin basic protein kinase activity that has identical ABA activation characteristics and demonstrate that tyrosine phosphorylation of MAP kinase occurs during activation. The half-maximal concentration of ABA required for MAP kinase activation, 3 x 10-7 M, is very similar to that required for ABA-induced rab16 gene expression. The tyrosine phosphatase inhibitor phenylarsine oxide can completely block ABA-induced MAP kinase activation and rab16 gene expression. These results lead us to conclude that ABA activates MAP kinase via a tyrosine phosphatase and that these steps are a prerequisite for ABA induction of rab16 gene expression. Show less
