Doctoral Candidate Technical University of Munich Zolling, Bayern, Germany
Body of Abstract: Among domesticated oil seed crops critical for both industrial and nutritional value, sunflower (Helianthus annuus L.) ranks second in Europe. Sunflower seeds are rich in the polyunsaturated fatty acid, linoleic acid, which is biosynthesized from oleic acid through activity of the oleate desaturase FATTY ACID DESATURASE 2 (FAD2). FAD2 is encoded by a single copy gene, FAD2-1, of which defective expression enriches oleic acid content, conferring a high oleic (HO) acid trait. Utility of the HO trait has been implicated in oil seed production for food-grade, pharmaceutical and biodiesel applications and consequently, is a trait of interest.
While possible for other oil seed crops such as soybean and rapeseed, a targeted mutagenesis of FAD2-1 cannot be achieved through genetic engineering in sunflower due to its highly recalcitrant nature towards regeneration, which impairs the establishment of efficient transformation procedures. Therefore, current strategies to obtain HO sunflowers require classical, untargeted mutation breeding; although this approach has been used in the past to generate fad2-1 sunflower mutants, genetic material with a stable HO trait remains limited.
Here we report a sunflower mutant population created using gamma irradiation and screened for fad2-1 mutants with a newly developed HPLC-based fatty-acid profiling system suitable for high-throughput analyses. With this approach, fad2-1 knock-out mutants could be isolated which stably hyper-accumulate oleic acid in concentration ranges of 85-90% of the total fatty acid pool. The genetic characterization of these sunflower lines not only demonstrates the nature of relevant HO functional mutations, but will facilitate marker development for the rapid introgression of the trait into elite sunflower breeding material.