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Phylogenetic Relationships in Orobanchaceae Inferred From Low-Copy Nuclear Genes: Consolidation of Major Clades and Identification of a Novel Position of the Non-photosynthetic Orobanche Clade Sister to All Other Parasitic Orobanchaceae.

Molecular phylogenetic analyses have greatly advanced our understanding of phylogenetic relationships in Orobanchaceae, a model system to study parasitism in angiosperms. As members of this group may lack some genes widely used for phylogenetic analysis and exhibit varying degrees of accelerated base substitution in other genes, relationships among major clades identified previously remain contentious. To improve inferences of phylogenetic relationships in Orobanchaceae, we used two pentatricopeptide repeat (PPR) and three low-copy nuclear (LCN) genes, two of which have been developed for this study. Resolving power and level of support strongly differed among markers. Despite considerable incongruence among newly and previously sequenced markers, monophyly of major clades identified in previous studies was confirmed and, especially in analyses of concatenated data, strongly supported after the exclusion of a small group of East Asian genera (Pterygiella and Phtheirospermum) from the Euphrasia-Rhinanthus clade. The position of the Orobanche clade sister to all other parasitic Orobanchaceae may indicate that the shift to holoparasitism occurred early in the evolution of the family. Although well supported in analyses of concatenated data comprising ten loci (five newly and five previously sequenced), relationships among major clades, most prominently the Striga-Alectra clade, the Euphrasia-Rhinanthus clade, and the Castilleja-Pedicularis clade, were uncertain because of strongly supported incongruence also among well-resolving loci. Despite the limitations of using a few selected loci, congruence among markers with respect to circumscription of major clades of Orobanchaceae renders those frameworks for detailed, species-level, phylogenetic studies.

RCSB Protein Data Bank: biological macromolecular structures enabling research and education in fundamental biology, biomedicine, biotechnology and energy.

The Research Collaboratory for Structural Bioinformatics Protein Data Bank (RCSB PDB, rcsb.org), the US data center for the global PDB archive, serves thousands of Data Depositors in the Americas and Oceania and makes 3D macromolecular structure data available at no charge and without usage restrictions to more than 1 million rcsb.org Users worldwide and 600 000 pdb101.rcsb.org education-focused Users around the globe. PDB Data Depositors include structural biologists using macromolecular crystallography, nuclear magnetic resonance spectroscopy and 3D electron microscopy. PDB Data Consumers include researchers, educators and students studying Fundamental Biology, Biomedicine, Biotechnology and Energy. Recent reorganization of RCSB PDB activities into four integrated, interdependent services is described in detail, together with tools and resources added over the past 2 years to RCSB PDB web portals in support of a 'Structural View of Biology.'