Turnip rape - a flexible and hardy oil crop for Sweden

The collection and characterization of spring turnip rape from a range of national and international sources have resulted in a genetically well-characterized population comprising 188 accessions, providing a valuable resource for future turnip rape breeding.

The spring turnip rape varieties developed within the Swedish plant breeding program exhibited limited genetic variation, restricting their potential for further improvement through breeding. In contrast, the substantial genetic differences observed between Scandinavian varieties and accessions from Asia, as well as wild and landrace material, represent significant opportunities for broadening the genetic base and enhancing future breeding efforts.

Conventional plant breeding approaches, including crossbreeding, field trials, greenhouse- and biotron-based experiments, disease resistance screening, and seed quality analyses, were integrated with development and optimizing molecular tools for turnip rape improvement. Genotyping-by-sequencing (GBS) was used to develop single nucleotide polymorphism (SNP) markers for genome-wide association studies (GWAS) and genomic prediction, enabling the estimation of genomic estimated breeding values (GEBVs) for target traits. Transcriptome analysis (RNA sequencing) was also conducted, providing additional resources, including SNP markers and differentially expressed genes associated with traits such as early flowering.

GWAS, involving field trials in southern and northern Sweden, identified more than sixty SNP markers associated with eight yield-related traits, including flowering- and maturity time, pod shattering resistance, plant height, thousand-seed weight, and seed yield. Selected SNPs can be converted into robust markers to support the implementation of Marker-assisted breeding and thus accelerate turnip rape improvement. Genes controlling flowering time were identified, providing opportunities to increase yield under the long-day conditions characteristic of northern Sweden. In addition, partial resistance to Sclerotinia stem rot was revealed through screening of the assembled spring turnip rape population indicating potential of this genetical resource as a source of desirable traits to improve the crop.

Conclusions

Over the course of five years, the turnip rape project collected and characterized an extensive germplasm collection, identified candidate genes and molecular markers associated with key traits, and generated knowledge, molecular resources, and methodological advances to support the future improvement of spring turnip rape breeding.

These achievements were made possible through successful collaboration between academic researchers and the national spring turnip rape breeding program.

Scaling up the breeding program through implementation of project outcomes, including marker-assisted selection and genomic selection, would enhance the long-term prospects of developing robust, high-yielding spring turnip rape varieties, particularly for northern Sweden.

Outcomes

Practical research training

Several students were involved in the project during its course: Ferdi Agil (Erasmus student from Turkey for 8 months), Inez Falk (BSc student for 6 months), and Mathieu Bernardini (MSc student for 6 months).

Master's thesis

Genomic and Transcriptomic Insights into the Adaptability of Turnip Rape (Brassica rapa subsp. oleifera) av Mathieu Bernardini, University of Grenoble Alpes, Frankrike, (2023).

Publications

Geleta, M., Sundaramoorthy, J., & Carlsson, A. S. (2024). SeqSNP-Based Targeted GBS Provides Insight into the Genetic Relationships among Global Collections of Brassica rapa ssp. oleifera (Turnip Rape). Genes, 15(9), 1187.

Alemu, A., Sundaramoorthy, J., Abreha, K. B., Enyew, M., Geleta, M., & Carlsson, A. S. (2024). Developing genomic tools to assist turnip rape [Brassica rapa (L.) subsp. oleifera (DC.) Metzg.] breeding. Frontiers in Genetics, 15, 1435474.

Continued research

Researchers involved in the project have been awarded funding from other sources for activities related to the project:

Turnip rape breeding for improving resistance to Sclerotinia sclerotiorum. KSLA, SEK 150,000, Kibrom Abreha (2021).

Development of an improved spring turnip rape cultivar with an earliness trait. KSLA, SEK 100,000, Jagadeesh Sundaramoorthy (2021).

Identification of genes and their polymorphisms to combat viral diseases. Formas, SEK 2,983,834. Anders Hafrén, principal applicant; Anders Carlsson, co-applicant (2023).

Projekt members

SLU: Mulatu Geleta, Jagadeesh Sundaramoorthy, Kibrom B. Abreha, Admas Abebe, Shrikant Sharma, Mirela Beganovic, Kaye Bateman, Anders Ekholm, Inez Falk, Ferdi Agil, Mathieu Bernardini, Muluken Enyew

Jerrestad Agro AB: Christer Persson

Hushållningssällskapet Norrbotten Västerbotten: Jan Nilsson, Ibrahem Alkhedr