Browsing by Subject "deoxynivalenol"

Fusarium Head Blight (FHB) is an important cereal disease worldwide and has become an essential breeding target in wheat. FHB generates considerable losses in terms of grain yield and quality of the seeds in cereal crops. The mycotoxins produced by some Fusarium species, such as deoxynivalenol (DON), directly impact the farmers. In fact, DON accumulation results in unmarketable harvest due to the associated health hazards (vomiting, diarrhea, fever etc). Facing DON risks, the European Commission had to establish a maximum concentration of the mycotoxin in unprocessed cereals. Avoidance mechanisms of the plants against disease infections were identified in diverse studies and are known as the passive resistance. These mechanisms related to phenotypic traits such as variations in plant height (PH), heading date (HD) or the presence of awns could possibly reduce the FHB infection of the wheat. On another hand, the active resistance is determined by genetic factors so called quantitative trait loci (QTL). QTL identification via population mapping was established to be a useful tool to find loci regions associated with FHB resistance. Therefore, in this study we aimed to find phenotypic and genotypic correlations with Fusarium Head Blight resistance among 108 winter bread wheat genotypes. By estimating the heritability of the agronomic traits, we wanted to determine if it would be efficient to breed for those traits. Furthermore, we had the objective to detect FHB resistance QTL from our winter bread wheat genotypes and finally, to observe the overlapping QTL’s regions between FHB resistance and the QTL of the HD or of the PH. It was found that the HD had strong negative phenotypic and genotypic coefficients of correlation with FHB severity and DON concentration. The HD had also an important heritability and direct effect on FHB severity. By performing a GWAS analysis, QTL associated to FHB resistance were found on the chromosomes 1B, 2B, 3A, 3B, 5A, 5B, 5D, 6A, 6B ,7B among the studied genotypes. Overlapping QTL were observed between FHB resistance and HD on the chromosomes 1B, 2B, 3B, 5A, 5B, 6B but also between FHB resistance and PH on the chromosomes 2B, 3A, 3B, 5A, 6A. In conclusion, the HD was considered as an escape mechanism against FHB. It seems to be feasible to select chromosomes fragments with favorable QTL for FHB genetic resistance. Those traits could be involved in marker assisted or genomic selection programmes after the approval of the observed QTL detected to develop FHB resistant cultivars.

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.

Gibberella zeae (Schwein.) Petch and its asexual form Fusarium graminearum Schwabe is a pathogen of oat, barley, wheat and maize that causes Fusarium head blight in cereals. F. graminearum produces mycotoxins that contaminate yields in humid and warm weather conditions. The pathogen spreads most effectively during its sexual stage. F. graminearum has become more common as a result of climate change and as reduced tillage has become more preferred in cultivation. This research was a part the Fustox Projet in Natural Resources Institute in Jokioinen research station. Develelopment of G.zeae in crop residues was studied. Crop residue samples were collected from no-till and tilled field plots in existing field trials in spring 2013. Occurrence of F. graminearum was studied in barley and oat from no-till and tilled field plots and in oat from a field trial of four tillage methods during the growing season 2013. Efficiency of two fungicides (DMI and DMI+QoI fungicides) were studied in two oat cultivars, barley and spring wheat in MTT Ylistaro research station. Yield samples were also analysed for deoxynivalenol (DON) contamination. Occurrence of the pathogen was determined by incubating straw pieces and kernels in laboratory conditions. Fusarium species were identified by their colony and spore morphology and colour. Contrary to expectations the pathogen was somewhat more prevalent in tilled plots than in reduced tillage. This may be due to greater microbe activity that is capable of decomposing or inhibiting the pathogen in fields with reduced tillage. In this study stem-bases were more infected by the pathogen in reduced tillage. Fungicide treatments were effective in reducing the occurrence of F. graminearum in the field and DON contamination in yield. There were no significant differences between fungicides. The most effective methods of controlling G. zeae and F. graminearum is selection resistant cultivars for cultivation. Careful selection of soil tillage method can also aid in controlling the pathogen.