DArTseq-Based, High-Throughput Identification of Novel Molecular Markers for the Detection of Blackleg (Leptosphaeria Spp.) Resistance in Rapeseed.

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.

Brassica napus Haploid and Double Haploid Production and Its Latest Applications.

Rapeseed is one of the most important oil crops in the world. Increasing demand for oil and limited agronomic capabilities of present-day rapeseed result in the need for rapid development of new, superior cultivars. Double haploid (DH) technology is a fast and convenient approach in plant breeding as well as genetic research. Brassica napus is considered a model species for DH production based on microspore embryogenesis; however, the molecular mechanisms underlying microspore reprogramming are still vague. It is known that morphological changes are accompanied by gene and protein expression patterns, alongside carbohydrate and lipid metabolism. Novel, more efficient methods for DH rapeseed production have been reported. This review covers new findings and advances in Brassica napus DH production as well as the latest reports related to agronomically important traits in molecular studies employing the double haploid rapeseed lines.

Quantifying Genetic Parameters for Blackleg Resistance in Rapeseed: A Comparative Study.

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.