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Recombination affects the fate of alleles in populations by imposing constraints on the reshuffling of genetic information. Understanding the genetic basis of these constraints is critical for manipulating the recombination process to improve the resolution of genetic mapping, and reducing the negative effects of linkage drag and deleterious genetic load in breeding. Using sequence-based genotyping of a wheat nested association mapping (NAM) population of 2,100 recombinant inbred lines created by crossing 29 diverse lines, we mapped QTL affecting the distribution and frequency of 102 000 crossovers (CO). Genome-wide recombination rate variation was mostly defined by rare alleles with small effects together explaining up to 48.6% of variation. Most QTL were additive and showed predominantly trans-acting effects. The QTL affecting the proximal COs also acted additively without increasing the frequency of distal COs. We showed that the regions with decreased recombination carry more single nucleotide polymorphisms (SNPs) with possible deleterious effects than the regions with a high recombination rate. Therefore, our study offers insights into the genetic basis of recombination rate variation in wheat and its effect on the distribution of deleterious SNPs across the genome. The identified trans-acting additive QTL can be utilized to manipulate CO frequency and distribution in the large polyploid wheat genome opening the possibility to improve the efficiency of gene pyramiding and reducing the deleterious genetic load in the low-recombining pericentromeric regions of chromosomes.

Crop populations have enormous impacts on agricultural productivity, yet decelerating gains from breeding suggest that selection strategies need to be reconsidered to better align priorities of breeders and growers. Breeders benefit from releasing broadly adapted varieties that perform acceptably well across their target region; growers benefit from selecting a variety that specializes in their specific location. We tested whether these interests are compatible using 182 entries in a mega‐population of malting barley (spring, two‐row, multi‐environment trial [S2MET] population; Hordeum vulgare L.), which was grown across the northern United States. We assessed the strength of genetic–environment interactions (G×E), quantified local adaptation benefits, and tested whether local adaptation and genetic yield potential were correlated. Breeding programs favored broad adaptation (p < 0.001). Still, 63% of entries (114) were among the top 10%, best performing at some locations, and among the worst 10% at others. Some of the best overall entries were specialists, performing especially well in their home locations, and in general, genetic potential and local specialization were positively correlated (p < 0.001). These results suggest that breeding for local performance and broad performance are mutually supporting goals. Releasing broadly excellent, locally exceptional varieties may accelerate genetic gain to meet projected global agricultural demand. Core Ideas: Releasing locally adapted varieties can accelerate genetic gain at the cost of breeding efficiency.We test whether locally and broadly adapted strategies are synergistic in the modern barley mega‐population, spring, two‐row, multi‐environment trial malting barley population (S2MET).Specialist lines tended to yield higher overall, indicating a synergy between these strategies.Broad adaptation at the population level indicated that breeders favored generalist lines.Releasing broadly excellent, locally exceptional varieties is feasible and better aligns breeder and grower needs. [ABSTRACT FROM AUTHOR]

Trichinellosis is a zoonotic disease caused by one of the most widely distributed parasite groups in the world, Trichinella. Infection and illness in humans occurs following the consumption of undercooked meat containing larvae. Many cases of trichinellosis go unreported, but symptomatic disease can present with nausea, diarrhea, vomiting, fatigue, and in severe cases, death. Since the eradication of Trichinella from the commercial swine industry, wildlife meat, specifically black bear and feral pig, has become the main cause of human trichinellosis in the United States. California continues to be home to the majority of these cases. Despite this change in epidemiology, few studies have focused on importance of wildlife as a reservoir of human trichinellosis. The most recently reported prevalence estimate of Trichinella in California black bears was over 30 years ago, in 1977. To our knowledge, there have been no published reports on the prevalence of Trichinella in California feral pigs. Furthermore, human, black bear, and feral pig population growth, coupled with increased urban development, has created an expanding ecological niche for parasite transmission, thus increasing the risk of Trichinella infection for consumers of wildlife meat. Given the lack of contemporary data and knowledge, there is a need to generate estimates of the current burden of Trichinella in California wildlife in order to assess the foodborne risk this potentially lethal parasite poses to the public.

In this study, we developed 359 detection primers for single nucleotide polymorphisms (SNPs) previously discovered within intron sequences of wheat genes and used them to evaluate SNP polymorphism in common wheat (Triticum aestivum L.). These SNPs showed an average polymorphism information content (PIC) of 0.18 among 20 US elite wheat cultivars, representing seven market classes. This value increased to 0.23 when SNPs were pre-selected for polymorphisms among a diverse set of 13 hexaploid wheat accessions (excluding synthetic wheats) used in the wheat SNP discovery project (http://wheat.pw.usda.gov/SNP). PIC values for SNP markers in the D genome were approximately half of those for the A and B genomes. D genome SNPs also showed a larger PIC reduction relative to the other genomes (P < 0.05) when US cultivars were compared with the more diverse set of 13 wheat accessions. Within those accessions, D genome SNPs show a higher proportion of alleles with low minor allele frequencies (