Browsing by Subject "Genome-wide association"

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  • Rehman, Attiq ur (Helsingin yliopisto, 2020)
    Wheat (Triticum aestivum L.) is one of the major crops in the world and an important agricultural commodity in Finland with various uses. Fusarium head blight (FHB) is a deadly disease of cereal crops and with the gradual increase in temperature and precipitation, it is becoming alarming to Finnish agriculture. Deoxynivalenol (DON) is a vomitoxin produced by Fusarium graminearum species during the FHB infection and is hazardous to health if taken in larger quantities by humans and animals. European Union has legalized the maximum allowed DON content in wheat flour for human consumption at 1.75 ppm. Various types of resistance against FHB are known till date, including tolerance and escape from the disease. Anther extrusion (AE) is a highly heritable trait in wheat and is mechanistically involved in resistance against FHB by preventing the availability of nutrients for the fungus. Other traits such as heading, maturity, and height have shown correlations with FHB incidence and severity in previous studies. Genomic information is crucial to identify markers to accelerate wheat breeding programs against FHB. This experiment was conducted at Boreal Plant Breeding Ltd. Finland using 198 spring wheat breeding lines in a row-and-column design with three replications in an artificially spawn-inoculated F. graminearum field. The goal of the project was to evaluate the genetic diversity for various agronomic and FHB-resistance traits and to estimate correlations among them. A genome-wide association study was also performed by using 11,987 SNP markers to investigate any marker-trait association(s) in the spring wheat breeding germplasm. Larger phenotypic variability was observed in both agronomic and FHB-resistance related traits. Many spurious associations were found with general linear models (Naïve and Q model). No marker-trait associations were observed among the traits in mixed linear model (K) after including kinship as a covariate. Cryptic relatedness among breeding lines has shown a significant role during association mapping. An unexpected negative correlation was found between DON and Fusarium severity indicating inaccuracies in phenotyping. A negative phenotypic and genotypic correlation was found between AE and DON. Future studies on the validation of AE as a phenotypic marker against DON accumulation is recommended. Repeating the experiment with the inclusion of more lines with Fhb1 gene in homozygous state might be helpful in finding reliable associations for FHB-resistance related traits.
  • Kafle, Madan (Helsingin yliopisto, 2020)
    Oat (Avena sativa L.) is the second largest cereal crop (in terms of production) in Finland and the prevalence of Fusarium graminearum in Nordic region is increasing. Infection by F. graminearum causes fusarium head blight (FHB) leading to accumulation of mycotoxin (deoxynivalenol) in addition to the reduction of yield. European union has set the limit for deoxynivalenol for unprocessed oat as 1.75 ppm. Therefore, it is a challenge for the production and marketing of oat to stay within the limit. Being aware of these problems and lack of much understanding in this area, this study was carried out at Boreal plant breeding company located in Jokioinen, Finland. It was aimed to check for associations between traits and markers in an oat field artificially inoculated with F. graminearum. The traits under consideration were plant height, maturity class, heading date, anther extrusion, deoxynivalenol content and germination capacity of kernels. To check the correlation between the traits and explore the variation existing in our germplasm was also the focus of this study. The experimental field was sown as row plots and after one month of sowing, it was inoculated with oat seeds infected with F. graminearum. The phenotypic data were recorded on suitable time and the genome-wide association study was carried out using genome association and prediction integrated tool in R software. Among the traits under consideration, maturity class showed an association with the markers and showed significant positive correlation with deoxynivalenol accumulation and can be considered for further study.