The increased use of diversity in cereal cropping requires more descriptive precision.

BACKGROUND: Until 100 years ago, cereals were grown only as populations with varying amounts of genetic diversity both within and among different crops. However, since the nineteenth century, methods for isolating and reproducing monocultural varieties have become universal, particularly among larger producers, leading to widespread within-field genetic monotony. A range of approaches is now being used to increase genetic diversity within and among crops including bringing back into cultivation a range of populations using a variety of different names, such as old varieties, landraces, ancient grains, heritage varieties, heirloom varieties, and mixtures. The objective of this paper, which is the result of the First International Conference on Landraces (Bologna, July 2018), is to contribute to the more precise definition of the names that are used more frequently. RESULTS: One early approach to increasing diversity among such monocultures was the use of variety mixtures, initially using static mixtures, meaning mixtures that were re-constituted from their original component varieties for each growing season. Some farmers, however, preferred to re-grow static mixtures from the harvested, and therefore selected, seed, thus converting them to what can be termed dynamic mixtures. Consequent natural inter-crossing within such dynamic mixtures means that, within a few seasons, following natural segregation, recombination and selection, they become populations. There is a wide body of literature on both static and dynamic mixtures, the discussion of which is beyond the scope of this paper. More recently, interest has been increasing in modern forms of evolutionary breeding of populations through direct hybridization of monocultural varieties followed by segregation and, commonly, natural selection, often in target production areas. As expected from evolutionary theory, such populations exhibit considerable resilience under variable environmental conditions, which is increasingly important in relation to the complexity of climate change. CONCLUSION: To help identify different approaches, and communicate information, definitions can be based on the approximate known historical age of the plant material in question and its genetic structure. © 2019 Society of Chemical Industry.

Natural Selection Towards Wild-Type in Composite Cross Populations of Winter Wheat.

Most of our crops are grown in monoculture with single genotypes grown over wide acreage. An alternative approach, where segregating populations are used as crops, is an exciting possibility, but outcomes of natural selection upon this type of crop are not well understood. We tracked allelic frequency changes in evolving composite cross populations of wheat grown over 10 generations under organic and conventional farming. At three generations, each population was genotyped with 19 SSR and 8 SNP markers. The latter were diagnostic for major functional genes. Gene diversity was constant at SSR markers but decreased over time for SNP markers. Population differentiation between the four locations could not be detected, suggesting that organic vs. non-organic crop management did not drive allele frequency changes. However, we did see changes for genes controlling plant height and phenology in all populations independently and consistently. We interpret these changes as the result of a consistent natural selection towards wild-type. Independent selection for alleles that are associated with plant height suggests that competition for light was central, resulting in the predominance of stronger intraspecific competitors, and highlighting a potential trade-off between individual and population performance.

Resilience as a universal criterion of health.

To promote and maintain health in agricultural and food systems, appropriate criteria are needed for the description and assessment of the health of soils, plants, animals, humans and ecosystems. Here we identify the concept of resilience as a universally applicable and fundamentally important criterion of health in all relevant areas of agriculture. We discuss definitions of resilience for soils, plants, animals, humans and ecosystems, and explore ways in which resilience can be applied as a criterion of health in different agricultural contexts. We show how and why resilience can be seen as a key criterion of health. Based on this, we discuss how resilience can be used as a link between soil, plant, animal, human and ecosystem health. Finally, we highlight four key areas for future research on resilience in agriculture, namely spatial and temporal scaling of resilience; effects of diversity; the role of networks for resilience; and stakeholder involvement.

Safety of Typhim Vi vaccine in a postmarketing observational study.

BACKGROUND: Typhoid fever is endemic in many parts of the world. In the United States, nearly three quarters of all cases are contracted by persons who traveled to regions with endemic disease. Typhim Vi, a vaccine containing the purified cell surface Vi polysaccharide of the Salmonella enterica serovar Typhi, was developed to provide protection against typhoid fever. We present the results of the largest safety study of this Vi vaccine to date. METHODS: This open-label, descriptive study assessed safety and reactogenicity following the Vi vaccine administration. Coadministration of other vaccines (at separate sites) was permitted, consistent with clinical practice. Participants aged 2 years or older with no known sensitivities to any vaccine component, who received the Vi vaccine, according to label directions, at a participating travel clinic, were eligible to participate. Information was collected on concurrent medications and medical conditions. The occurrence of solicited injection site reactions and systemic reactions was recorded on diary cards for 7 days following vaccination, along with any unsolicited medical events. Serious adverse events were reported for 30 days postimmunization. RESULTS: A total of 1,204 participants (mean age: 37.2 y, range: 2-82 y, 55% female) were enrolled into the study, and 1,111 completed the 7-day follow-up. The most common solicited reactions were injection site pain [850 of 1,111 (76.5%)], tenderness [838 of 1,111 (75.4%)], and muscle aches [434 of 1,111 (39.1%)]. Fever was reported in 18 (1.6%) of 1,111 participants. Coadministration of other common travel vaccines did not affect reactogenicity profiles, except for an increase in the Vi vaccine injection site redness when two vaccines were administered in the same limb. CONCLUSIONS: The Vi vaccine was well tolerated in an unselected population, aged 2 to 82 years, presenting to a travel clinic for vaccination.

Historical Lassa fever reports and 30-year clinical update.

Five cases of Lassa fever have been imported from West Africa to the United States since 1969. We report symptoms of the patient with the second imported case and the symptoms and long-term follow-up on the patient with the third case. Vertigo in this patient has persisted for 30 years.