SummaryBrassica napus is one of the most important oil crops in the world, and stem rot caused by the fungus Sclerotinia sclerotiorum results in major losses in yield and quality. To elucidate resistance genes and pathogenesis-related genes, genome-wide association analysis of 347 accessions was performed using the Illumina 60K Brassica SNP (single nucleotide polymorphism) array. In addition, the detached stem inoculation assay was used to select five highly resistant (R) and susceptible (S) B. napus lines, 48 h postinoculation with S. sclerotiorum for transcriptome sequencing. We identified 17 significant associations for stem resistance on chromosomes A8 and C6, five of which were on A8 and 12 on C6. The SNPs identified on A8 were located in a 409-kb haplotype block, and those on C6 were consistent with previous QTL mapping efforts. Transcriptome analysis suggested that S. sclerotiorum infection activates the immune system, sulphur metabolism, especially glutathione (GSH) and glucosinolates in both R and S genotypes. Genes found to be specific to the R genotype related to the jasmonic acid pathway, lignin biosynthesis, defence response, signal transduction and encoding transcription factors. Twentyfour genes were identified in both the SNP-trait association and transcriptome sequencing analyses, including a tau class glutathione S-transferase (GSTU) gene cluster. This study provides useful insight into the molecular mechanisms underlying the plant's response to S. sclerotiorum.

The Chinese genebank contains 23,587 soybean landraces collected from 29 provinces. In this study, a representative collection of 1,863 landraces were assessed for genetic diversity and genetic diVerentiation in order to provide useful information for eVective management and utilization. A total of 1,160 SSR alleles at 59 SSR loci were detected including 97 unique and 485 low-frequency alleles, which indicated great richness and uniqueness of genetic variation in this core collection. Seven clusters were inferred by STRUCTURE analysis, which is in good agreement with a neighbor-joining tree. The cluster subdivision was also supported by highly signiWcant pairwise F st values and was generally in accordance with diVerences in planting area and sowing season. The cluster HSuM, which contains accessions collected from the region between 32.0 and 40.5°N, 105.4 and 122.2°E along the central and downstream parts of the Yellow River, was the most genetically diverse of the seven clusters. This provides the Wrst molecular evidence for the hypotheses that the origin of cultivated soybean is the Yellow River region. A high proportion (95.1%) of pairs of alleles from diVerent loci was in LD in the complete dataset. This was mostly due to overall population structure, since the number of locus pairs in LD was reduced sharply within each of the clusters compared to the complete dataset. This shows that population structure needs to be accounted for in association studies conducted within this collection. The low value of LD within the clusters can be seen as evidence that much of the recombination events in the past have been maintained in soybean, Wxed in homozygous self-fertilizing landraces.

To determine the contents of heavy metal (Cu, Zn, As, Cr, Cd and Pb) in animal feeds and manures, 104 livestock feeds and 118 animal manure samples from farms of different herd size and located in northeast China were collected and their heavy metal concentrations were determined. The content of Cu, As and Cd ranged from 2.3–1,137.1 mg/kg dm, 0.02–13.03 mg/kg dm and non-detectable (nd)−31.65 mg/kg dm in pig feeds, 2.88–98.08 mg Cu/kg dm, 0.02–6.42 mg As/kg dm and non-detectable (nd)–8.00 mg Cd/kg dm in poultry feeds, and their content in cattle feeds was similar to that in poultry feeds. The typical content in pig manures was 642.1 mg Cu/kg dm, 8.6 mg As/kg dm, and 15.1 mg Cd/kg dm, which reflected the metal contents in feeds. The typical contents in poultry manures were 65.6 mg Cu/kg dm, 3.3 mg As/kg dm and 1.6 mg Cd/kg dm while the contents in cattle manures were 31.1 mg Cu/kg dm, 2.5 mg As/kg dm and 0.5 mg Cd/kg dm. Animal manure is an important source of heavy metals to the environment in Northeast China.