No abstract

The African Diaspora in the Western Hemisphere represents one of the largest forced migrations in history and had a profound impact on genetic diversity in modern populations. To date, the fine-scale population structure of descendants of the African Diaspora remains largely uncharacterized. Here we present genetic variation from deeply sequenced genomes of 642 individuals from North and South American, Caribbean and West African populations, substantially increasing the lexicon of human genomic variation and suggesting much variation remains to be discovered in African-admixed populations in the Americas. We summarize genetic variation in these populations, quantifying the postcolonial sex-biased European gene flow across multiple regions. Moreover, we refine estimates on the burden of deleterious variants carried across populations and how this varies with African ancestry. Our data are an important resource for empowering disease mapping studies in African-admixed individuals and will facilitate gene discovery for diseases disproportionately affecting individuals of African ancestry.

Summary Pathogen‐associated molecular patterns (PAMPs) are conserved molecules that are crucial for normal life cycle of microorganisms. However, the diversity of microbial PAMPs is little known. During screening of cell‐death‐inducing factors from the necrotrophic fungus Valsa mali, we identified a novel PAMP VmE02 that is widely spread in oomycetes and fungi. Agrobacterium tumefaciens‐mediated transient expression or infiltration of recombinant protein produced by Escherichia coli was performed to assay elicitor activity of the proteins tested. Virus‐induced gene silencing in Nicotiana benthamiana was used to determine the components involved in VmE02‐triggered cell death. The role of VmE02 in virulence and conidiation of V. mali were characterized by gene deletion and complementation. We found that VmE02, together with some of its homologues from both oomycete and fungal species, exhibited cell‐death‐inducing activity in N. benthamiana. VmE02‐triggered cell death was shown to be dependent on BRI1‐ASSOCIATED KINASE‐1, SUPPRESSOR OF BIR1‐1, HSP90 and SGT1 in N. benthamiana. Deletion of VmE02 in V. mali greatly attenuated pathogen conidiation but not virulence, and treatment of N. benthamiana with VmE02 enhances plant resistance to Sclerotinia sclerotiorum and Phytophthora capsici. We conclude that VmE02 is a novel cross‐kingdom PAMP produced by several fungi and oomycetes.

Proteins encoded by the NAC gene family constitute one of the largest plant-specific transcription factors, which have been identified to play many important roles in both abiotic and biotic stress adaptation, as well as in plant development regulation. In the current paper, a full-length cDNA sequence of a novel wheat NAC gene, designated as TaNAC4, was isolated using in silico cloning and the reverse transcription PCR (RT-PCR) methods. TaNAC4 sharing high homology with rice OsNAC4 gene was predicted to encode a protein of 308 amino acid residues, which contained a plant-specific NAC domain in the N-terminus. Transient expression analysis indicated that the deduced TaNAC4 protein was localized in the nucleus of onion epidemical cells. Yeast one-hybrid assay revealed that the C-terminal region of the TaNAC4 protein had transcriptional activity. The expression of TaNAC4 was largely higher in the wheat seedling roots, than that in leaves and stems. TaNAC4 transcript in wheat leaves was induced by the infection of strip rust pathogen, and also by exogenous applied methyl jasmonate (MeJA), ABA and ethylene. However, salicylic acid (SA) had no obvious effect on TaNAC4 expression. Environmental stimuli, including high salinity, wounding, and low-temperature also induced TaNAC4 expression. These results indicate that this novel TaNAC4 gene functions as a transcriptional activator involved in wheat response to biotic and abiotic stresses.

Background: Puccinia striiformis f. sp. tritici is a fungal pathogen causing stripe rust, one of the most important wheat diseases worldwide. The fungus is strictly biotrophic and thus, completely dependent on living host cells for its reproduction, which makes it difficult to study genes of the pathogen. In spite of its economic importance, little is known about the molecular basis of compatible interaction between the pathogen and wheat host. In this study, we identified wheat and P. striiformis genes associated with the infection process by conducting a large-scale transcriptomic analysis using cDNA-AFLP.