Epsilon Archive for Student Projects

Abstract

Havre är en av människans basgrödor och konsumeras därmed i stora mängder. Studier har visat att havre tar upp tungmetallen kadmium (Cd) från marken den odlas på, vilket gör att små mängder ackumuleras i havrets kärna. Kadmium är skadligt för både växten och människan och har visat sig orsaka både cancer och benskörhet och enligt European Food Safety Authority (EFSA) krävs endast en liten mängd för att det ska vara skadligt. Förutom rökning är kosten den största källan till Cd-exponering där spannmål utgör 40% av det dagliga intaget av tungmetallen. Högst Cd-ackumulering bland spannmål har visats i ris och durumvete, lägre i vete och lägst i havre. För vegetarianer är risken ännu större eftersom de äter mer vegetabilisk kost. Barn är också en riskgrupp eftersom kadmium ackumuleras i kroppen över tid, vilket leder till att de löper högre risk för skador. För de minsta barnen är risken stor då barnmatsprodukter som välling och gröt baseras på havre. Kadmium tas upp av havre på grund av dess kemiska likhet med j

Oats are one of the staple crops of humans and are therefore consumed in large quantities. Studies have shown that oats absorb the heavy metal cadmium (Cd) from the soil in which it is grown, which causes small amounts to accumulate in the oat kernel. Cadmium is harmful to both plants and humans and has been shown to cause both cancer and osteoporosis, and according to the European Food Safety Authority (EFSA), only a small amount is required for it to be harmful. In addition to smoking, the diet is the largest source of cadmium intake, where cereals have been shown to constitute 40% of the daily intake of the heavy metal. The highest Cd accumulation among cereals has been shown in rice and durum wheat, lower in wheat and lowest in oats. For vegetarians, the risk is even greater because they eat a more plant-based diet. Children are also a risk group because cadmium accumulates in the body over time, which puts them at higher risk of damage. For the youngest children, the risk is great because baby food products such as gruel and porridge are based on oats. Cd is taken up by oats due to its chemical similarity to iron and zinc. Environmental characteristics such as bedrock material, pH, clay and silt content and biochar can either facilitate or inhibit the uptake of the heavy metal. Higher Cd content in the soil can also be due to emissions from industries and fertilizers. Uptake and accumulation of Cd are also controlled by genetics and differ between species and varieties. Plant breeders can use chemical analysis methods to select individuals with lower Cd content, but the problem is that these are both costly, labour-intensive, and time-consuming. Therefore, the use of molecular markers can be used to select plants at an early growth stage and early in the breeding program at a lower cost. The genome (genetic material) of oats is less studied, and genetic studies of Cd accumulation in oats are still limited. A previous study identified markers associated with Cd content in oat kernels, but without a connection to physical genome maps. In the SLU-Grogrund project "Against winter wheat and oat varieties with low cadmium accumulation", genetic analyses with SNPs spread across the genome are used to identify reliable markers linked to lower Cd levels in the oat kernel that can facilitate the selection process in Lantmännen's breeding program. This study analysed the cadmium content in oat kernel from 435 breeding lines from Lantmännen using 6642 markers. The lines were grown at three different locations (Svalöv, Bjertorp and Kölbäck) during the years 2022–2024. The analysis was performed with a Genome-Wide Association Study (GWAS) to identify which genetic regions (QTL) are linked to lower Cd accumulation in the oat kernel. Phenotypic data were analysed with analysis of variance ANOVA, correlation analyses between environments and broad-sense heritability (H2), which showed a large genetic variation, while ANOVA (type III) resulted in strong environmental and genetic effects. BLUEs (Best Linear Unbiased Estimates) were used to derive environmentally adjusted phenotype values for use in GWAS. Eight significant SNP markers were identified with a -log10(p-value) above 5.8, with several of them located on chromosome 7A and one of the markers occurring in both models used, Bayesian information and Linkage-disequilibrium Iteratively Nested Keyway (BLINK) and Multi Loci Mixed Model (MLMM). Three significant markers were analysed for allelic combinations, and the results indicated that the breeding lines with the allelic combinations ‘TGC’ and ‘TTT’ had the lowest cadmium levels in the kernel, based on mean BLUEs (0.028 and 0.035).