Insight into the evolution of the Solanaceae from the parental genomes of Petunia hybrida

Petunia hybrida is a popular bedding plant that has a long history as a genetic model system. We report the whole-genome sequencing and assembly of inbred derivatives of its two wild parents, P. axillaris N and P. inflata S6. The current assemblies include 91.3% and 90.2% coverage of their diploid genomes (1.4 Gb; 2n=14) containing 32,928 and 36,697 protein-coding genes, respectively. The Petunia lineage has experienced at least two rounds of paleohexaploidization, the older gamma hexaploidy event, which is shared with other Eudicots, and the more recent Solanaceae paleohexaploidy event that is shared with tomato and other Solanaceae species. Transcription factors that were targets of selection during the shift from bee- to moth pollination reside in particularly dynamic regions of the genome, which may have been key to the remarkable diversity of floral color patterns and pollination systems. The high quality genome sequences will enhance the value of Petunia as a model system for basic and applied research on a variety of unique biological phenomena

PERIOD1 coordinates hippocampal rhythms and memory processing with daytime

In species ranging from flies to mammals, parameters of memory processing, like acquisition, consolidation, and retrieval are clearly molded by time of day. However, mechanisms that regulate and adapt these temporal differences are elusive, with an involvement of clock genes and their protein products suggestive. Therefore, we analyzed initially in mouse hippocampus the daytime-dependent dynamics of parameters, known to be important for proper memory formation, like phosphorylation of the "memory molecule" cyclic adenosine monophosphate (cAMP) responsive element binding protein (CREB) and chromatin remodeling. Next, in an effort to characterize the mechanistic role of clock genes within hippocampal molecular dynamics, we compared the results obtained from wildtype (WT) -mice and mice deficient for the archetypical clock gene Period1 (Per1-mice). We detected that the circadian rhythm of CREB phosphorylation in the hippocampus of WT mice disappeared completely in mice lacking Per1. Furthermore, we found that the here for the first time described profound endogenous day/night rhythms in histone modifications in the hippocampus of WT-mice are markedly perturbed in Per1-mice. Concomitantly, both, in vivo recorded LTP, a cellular correlate for long-term memory, and hippocampal gene expression were significantly altered in the absence of Per1. Notably, these molecular perturbations in Per1-mice were accompanied by the loss of daytime-dependent differences in spatial working memory performance. Our data provide a molecular blueprint for a novel role of PER1 in temporally shaping the daytime-dependency of memory performance, likely, by gating CREB signaling, and by coupling to downstream chromatin remodeling

Insight into the evolution of the Solanaceae from the parental genomes of Petunia hybrida

Petunia hybrida is a popular bedding plant that has a long history as a genetic model system. We report the whole-genome sequencing and assembly of inbred derivatives of its two wild parents, P. axillaris N and P. inflata S6. The assemblies include 91.3% and 90.2% coverage of their diploid genomes (1.4 Gb; 2n = 14) containing 32,928 and 36,697 protein-coding genes, respectively. The genomes reveal that the Petunia lineage has experienced at least two rounds of hexaploidization: the older gamma event, which is shared with most Eudicots, and a more recent Solanaceae event that is shared with tomato and other solanaceous species. Transcription factors involved in the shift from bee to moth pollination reside in particularly dynamic regions of the genome, which may have been key to the remarkable diversity of floral colour patterns and pollination systems. The high-quality genome sequences will enhance the value of Petunia as a model system for research on unique biological phenomena such as small RNAs, symbiosis, self-incompatibility and circadian rhythms