Breeding New Peanut Line with High Oleic Acid Content Using Backcross Method.

F₁ hybrids and BC₁F₁-BC₄F₁ backcross generation were obtained by cross and backcross with peanut variety HY22 as female parent (recurrent parent) and Kainong 176 with high oleic acid content as the donor parent. The contents of oleic acid and linoleic acid of F₁ and BC₁F₁ to BC₄F₁ were determined by Near infrared spectrometer. The seeds with oleic acid content higher than 60% were selected and their partial cotyledon was cut off for DNA extraction. The loci FAD2a and FAD2b in these seeds were detected by sequencing absorption peaks of PCR products with F0.7/R3 as primers, and those seeds with both FAD2a and FAD2b were used as the male parent in following backcross. The incision in these seeds whose cotyledon was cut off was sealed by paraffin oil, and these seeds were soaked in water for sprouting at 40°C. Those seeds that did not germinate within 12 hours were soaked in 100 mg L^-1 ethephon solution for four hours, then immersed into water till 24 hours at 40°C by which 98% seeds could germinate. Four to five times of backcross every two years were finished in spring in Qingdao, 1-2 times in autumn and winter in Sanya, by which the breeding process might be accelerated. The backcrossing work began in the spring of 2013 and BC₄F₂ seeds were sowed in Qingdao in the spring of 2016. The young leaves were used for genotyping and these plants with aabb genotype and similar agronomic characters with Huayu 22 were selected and harvested, whose oleic content was then confirmed by NIR. Twenty single plants with similar characters of Huayu 22 whose oleic content was higher than 70% and oleic/linoleic ratio was higher than 7.0 were regarded as a new improved HY22 strain with high oleic acid content. [ABSTRACT FROM AUTHOR]