Isolates of recently spreading races of yellow rust from wheat and triticale in Europe were analysed using virulence phenotypic data of 2605 isolates sampled in 12 countries between 2000 and 2014. A subset of 239 isolates was investigated by microsatellite markers. At least three races of non-European origin, termed 'Warrior', 'Kranich' and 'Triticale aggressive', were identified in the post-2011 population. The Warrior race was already present in high frequencies in the first year of detection in most European countries and to a large extent it replaced the pre-2011 European population. In contrast, the two other exotic races were localized to certain regions and/or crop type. The presence already of at least six multilocus genotypes of the Warrior race and five genotypes of the Kranich race in the first year of detection and across large areas is consistent with a hypothesis of aerial spread from genetically diverse source populations. A comparison with reference isolates sampled from six continents suggested that the Warrior and Kranich races originated from sexually recombining populations in the centre of diversity of the yellow rust fungus in the near-Himalayan region of Asia. However, the Triticale aggressive race was most similar to populations in the Middle East/Central Asia. The study illustrated the potential role of sexual Puccinia striiformis populations as a reservoir for new races replacing distant clonal populations.

Background: Emerging and re-emerging pathogens imperil public health and global food security. Responding to these threats requires improved surveillance and diagnostic systems. Despite their potential, genomic tools have not been readily applied to emerging or re-emerging plant pathogens such as the wheat yellow (stripe) rust pathogen Puccinia striiformis f. sp. tritici (PST). This is due largely to the obligate parasitic nature of PST, as culturing PST isolates for DNA extraction remains slow and tedious.

Previous research has demonstrated that great ape and macaque males achieve large canine crown sizes primarily through extended canine growth periods. Recent work has suggested, however, that platyrrhine males may achieve larger canine sizes by accelerating rather than prolonging growth. This study tested the hypothesis that the ontogenetic pathway leading to canine sexual dimorphism in catarrhines differs from that of platyrrhines. To test this hypothesis, males and females of several catarrhine genera (Hylobates, Papio, Macaca, Cercopithecus, and Cercocebus) and three platyrrhine genera (Cebus, Ateles, and Callicebus) were compared in the number and spacing of perikymata (enamel growth increments) on their canine crowns. In addition, perikymata periodicities (the number of days of growth perikymata represent) were determined for five genera (Hylobates, Papio, Macaca, Cebus, and Ateles) using previously published as well as original data gathered for this study. The central findings are as follows: 1) males have more perikymata than females for seven of eight genera (in five of the seven, the differences are statistically significant); 2) in general, the greater the degree of sexual dimorphism, the greater the sex difference in male and female perikymata numbers; 3) there is no evidence of a systematic sex difference in primate periodicities; and 4) there is some evidence that sex differences in enamel formation rates may make a minor contribution to canine sexual dimorphism in Papio and Cercopithecus. These findings strongly suggest that in both catarrhines and platyrrhines prolongation of male canine growth is the primary mechanism by which canine crown sexual dimorphism is achieved.

Recent disease outbreaks caused by (re-)emerging plant pathogens have been associated with expansions in pathogen geographic distribution and increased virulence. For example, in the past two decades’ wheat yellow (stripe) rust, Puccinia striiformis f. sp. tritici, has seen the emergence of new races that are adapted to warmer temperatures, have expanded virulence profiles, and are more aggressive than previous races, leading to wide-scale epidemics. Here, we used field-based genotyping to generate high-resolution data on P. striiformis genetics and carried out global population analysis. We also undertook comparative analysis of the 2014 and 2013 UK populations and assessed the temporal dynamics and host specificity of distinct pathogen genotypes. Our analysis revealed that P. striiformis lineages recently detected in Europe are extremely diverse and in fact similar to globally dispersed populations. In addition, we identified a considerable shift in the UK P. striiformis population structure including the first identification of one infamous race known as Kranich. Next, by establishing the genotype of both the pathogen and host within a single infected field sample, we uncovered evidence for varietal specificity for genetic groups of P. striiformis. Finally, we found potential seasonal specificity for certain genotypes of the pathogen with several lineages identified only in samples collected in late spring and into the summer, whereas one lineage was identified throughout the wheat growing season. Our discovery of which wheat varieties are susceptible to which specific P. striiformis isolates, and when those isolates are prevalent throughout the year, represents a powerful tool for disease management.

Nonhost resistance is often conceptualized as a qualitative separation from host resistance. Classification into these two states is generally facile, as they fail to fully describe the range of states that exist in the transition from host to nonhost. This poses a problem when studying pathosystems that cannot be classified as either host or nonhost due to their intermediate status relative to these two extremes. In this study, we investigate the efficacy of the Poaceae-stripe rust (Puccinia striiformis Westend.) interaction for describing the host–nonhost landscape. First, using barley (Hordeum vulgare L.) and Brachypodium distachyon (L.) P. Beauv. We observed that macroscopic symptoms of chlorosis and leaf browning were associated with hyphal colonization by P. striiformis f. sp. tritici, respectively. This prompted us to adapt a protocol for visualizing fungal structures into a phenotypic assay that estimates the percent of leaf colonized. Use of this assay in intermediate host and intermediate nonhost systems found the frequency of infection decreases with evolutionary divergence from the host species. Similarly, we observed that the pathogen’s ability to complete its life cycle decreased faster than its ability to colonize leaf tissue, with no incidence of pustules observed in the intermediate nonhost system and significantly reduced pustule formation in the intermediate host system as compared to the host system, barley-P. striiformis f. sp. hordei. By leveraging the stripe rust pathosystem in conjunction with macroscopic and microscopic phenotypic assays, we now hope to dissect the genetic architecture of intermediate host and intermediate nonhost resistance using structured populations in barley and B. distachyon.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 2" " ABSTRACT This study investigates whether variants in dental morphology and nuclear DNA provide similar patterns of intergroup affinity among regional populations using biological distance (biodistance) estimates. Many biodistance studies of archaeological populations use skeletal variants in lieu of ancient DNA, based on the widely accepted assumption of a strong correlation between phenetic-and genetic-based affinities. Within studies of dental morphology, this assumption has been well supported by research on a global scale but remains unconfirmed at a more geographically restricted scale.Paired genetic (42 microsatellite loci) and dental (nine crown morphology traits) data were collected from 295 individuals among four contemporary Kenyan populations, two of which are known ethnically as "Swahili" and two as "Taita;" all have well-documented population histories. The results indicate that biodistances based on genetic data are correlated with those obtained from dental morphology. Specifically, both distance matrices indicate that the closest affinities are between population samples within each ethnic group. Both also identify greater divergence among samples from the different ethnic groups. However, for this particular study the genetic data may provide finer resolution at detecting overall among-population relationships.

Crop losses caused by plant pathogens are a primary threat to stable food production. Stripe rust (Puccinia striiformis) is a fungal pathogen of cereal crops that causes significant, persistent yield loss. Stripe rust exhibits host species specificity, with lineages that have adapted to infect wheat and barley. While wheat stripe rust and barley stripe rust are commonly restricted to their corresponding hosts, the genes underlying this host specificity remain unknown. Here, we show that three resistance genes, Rps6, Rps7, and Rps8, contribute to immunity in barley to wheat stripe rust. Rps7 cosegregates with barley powdery mildew resistance at the Mla locus. Using transgenic complementation of different Mla alleles, we confirm allele-specific recognition of wheat stripe rust by Mla. Our results show that major resistance genes contribute to the host species specificity of wheat stripe rust on barley and that a shared genetic architecture underlies resistance to the adapted pathogen barley powdery mildew and non-adapted pathogen wheat stripe rust.

Recent work suggests that an autosomal dominant gene for schizophrenia may be located on the 5q11-q13 region of chromosome 5 (refs 1 and 2): a report of schizophrenia associated with trisomy 5q11-q13 in two members of a family of Chinese origin prompted the discovery of linkage with markers p105-599Ha and p105-153Ra in five Icelandic and two English schizophrenic families. The strongest linkage was observed when the phenotype was broadly defined to include minor psychiatric diagnoses not traditionally considered part of the schizophrenia spectrum. By contrast, no evidence was found of linkage in a single multiplex Swedish schizophrenic pedigree. To determine whether these conflicting results arise from genetic and/or uncertainties in defining the schizophrenic phenotype, we examined fifteen Scottish schizophrenic families with restriction fragment length polymorphisms that span this region. We found no evidence for linkage, regardless of how broadly or narrowly the schizophrenic phenotype is defined, and conclude that a susceptibility locus, whose presence awaits confirmation, on the proximal portion of the long arm of chromosome 5 can be responsible for only a minority of cases of familial schizophrenia.