Molecular breeding to develop advanced lines with high oleic acid and pod yield in peanut

Abstract

Peanut (Arachis hypogaea L.) is an important crop, and its seeds contain high amounts of protein and oil. The high oleic acid content of peanut oil provides prolonged shelf life and health benefits. Delta-12-desaturase (oleoyl-PC desaturase) is a key enzyme that catalyzes the conversion of oleic acid into linoleic acid and is coded by two homologs genes: ahFAD2A and ahFAD2B. It is known that plants with both point mutations (aabb) in these genes fail to produce Δ-12-desaturase enzyme cause to higher oleic acid. In this study, we employed marker-assisted breeding to develop high-oleic and high-pod-yield lines using a population sourced from crosses between a high-yield cultivar, NC-7 and an advanced high-oleic line, HOG. The oleic acid character of the parents was initially confirmed using molecular markers and fatty acid composition analyses. After crossing, two “true hybrids” were selected from the F1 generation with the use of an allele-specific marker. True hybrids were selfed and the fatty acids profiles of selected F2 plants with higher pod yield and seed length were determined. These two F2 populations (NH-2 and NH-3) having high levels of oleic acid were advanced to further generations. Single plants in F3 to F6 were selected and selfed based on seed yield and pod features. Finally, a total of 21 advanced inbred lines with high pod yields and oleic acid content of up to 83.3% were obtained. The ahFAD2B gene of selected high oleic lines were also sequenced and homozygous insertion was confirmed based on the reference genome. The oleic/linoleic ratio was increased to 39.0 with regard to cultivar NC-7, which was only 2.9. The advanced lines reported here showed combine high oleic content with desired agronomic traits and that this can meet the market demand for high-quality vegetable oil.