2024, Bocianowski, Jan, Starosta, Ewa, Jamruszka, Tomasz, Szwarc, Justyna, Jędryczka, Małgorzata, Grynia, Magdalena, Niemann, Janetta, Uniwersytet Przyrodniczy w Poznaniu

Selection is a fundamental part of the plant breeding process, enabling the identification and development of varieties with desirable traits. Thanks to advances in genetics and biotechnology, the selection process has become more precise and efficient, resulting in faster breeding progress and better adaptation of crops to environmental challenges. Genetic parameters related to gene additivity and epistasis play a key role and can influence decisions on the suitability of breeding material. In this study, 188 rapeseed doubled haploid lines were assessed in field conditions for resistance to Leptosphaeria spp. Through next-generation sequencing, a total of 133,764 molecular markers (96,121 SilicoDArT and 37,643 SNP) were obtained. The similarity of the DH lines at the phenotypic and genetic levels was calculated. The results indicate that the similarity at the phenotypic level was markedly different from the similarity at the genetic level. Genetic parameters related to additive gene action effects and epistasis (double and triple) were calculated using two methods: based on phenotypic observations only and using molecular marker observations. All evaluated genetic parameters (additive, additive-additive and additive-additive-additive) were statistically significant for both estimation methods. The parameters associated with the interaction (double and triple) had opposite signs depending on the estimation method.

2024, Bocianowski, Jan, Niemann, Janetta, Jagieniak, Anna, Szwarc, Justyna

Genetic similarity determines the extent to which two genotypes share common genetic material. It can be measured in various ways, such as by comparing DNA sequences, proteins, or other genetic markers. The significance of genetic similarity is multifaceted and encompasses various fields, including evolutionary biology, medicine, forensic science, animal and plant breeding, and anthropology. Genetic similarity is an important concept with wide application across different scientific disciplines. The research material included 21 rapeseed genotypes (ten interspecific Brassicaceae hybrids of F2 generation and 11 of their parental forms) and 146 alleles obtained using 21 ISSR molecular markers. In the presented study, six measures for calculating genetic similarity were compared: Euclidean, Jaccard, Kulczyński, Sokal and Michener, Nei, and Rogers. Genetic similarity values were estimated between all pairs of examined genotypes using the six measures proposed above. For each genetic similarity measure, the average, minimum, maximum values, and coefficient of variation were calculated. Correlation coefficients between the genetic similarity values obtained from each measure were determined. The obtained genetic similarity coefficients were used for the hierarchical clustering of objects using the unweighted pair group method with an arithmetic mean. A multiple regression model was written for each method, where the independent variables were the remaining methods. For each model, the coefficient of multiple determination was calculated. Genetic similarity values ranged from 0.486 to 0.993 (for the Euclidean method), from 0.157 to 0.986 (for the Jaccard method), from 0.275 to 0.993 (for the Kulczyński method), from 0.272 to 0.993 (for the Nei method), from 0.801 to 1.000 (for the Rogers method) and from 0.486 to 0.993 (for the Sokal and Michener method). The results indicate that the research material was divided into two identical groups using any of the proposed methods despite differences in the values of genetic similarity coefficients. Two of the presented measures of genetic similarity (the Sokal and Michener method and the Euclidean method) were the same.

2024, Starosta, Ewa, Jamruszka, Tomasz, Szwarc, Justyna, Bocianowski, Jan, Jędryczka, Małgorzata, Grynia, Magdalena, Niemann, Janetta

Blackleg disease, caused by Leptosphaeria spp. fungi, is one of the most important diseases of Brassica napus, responsible for severe yield losses worldwide. Blackleg resistance is controlled by major R genes and minor quantitative trait loci (QTL). Due to the high adaptation ability of the pathogen, R-mediated resistance can be easily broken, while the resistance mediated via QTL is believed to be more durable. Thus, the identification of novel molecular markers linked to blackleg resistance for B. napus breeding programs is essential. In this study, 183 doubled haploid (DH) rapeseed lines were assessed in field conditions for resistance to Leptosphaeria spp. Subsequently, DArTseq-based Genome-Wide Association Study (GWAS) was performed to identify molecular markers linked to blackleg resistance. A total of 133,764 markers (96,121 SilicoDArT and 37,643 SNP) were obtained. Finally, nine SilicoDArT and six SNP molecular markers were associated with plant resistance to Leptosphaeria spp. at the highest significance level, p < 0.001. Importantly, eleven of these fifteen markers were found within ten genes located on chromosomes A06, A07, A08, C02, C03, C06 and C08. Given the immune-related functions of the orthologues of these genes in Arabidopsis thaliana, the identified markers hold great promise for application in rapeseed breeding programs.