ABSCISIC ACID-INSENSITIVE 5-ω3 FATTY ACID DESATURASE3 module regulates unsaturated fatty acids biosynthesis in Paeonia ostii.

Paeonia ostii is an authorized novel vegetable oil crop due to its seeds rich in unsaturated fatty acids (UFAs) especially α-linolenic acid (ALA), which overweight the current available edible oil. However, little is known on the regulation mechanism of UFAs biosynthesis during its seed development. Here, we used transcriptome and proteome data combining phytochemistry means to uncover the relationship between abscisic acid (ABA) signaling and UFAs biosynthesis during P. ostii seed development. Based on transcriptome and proteome analysis, two desaturases of omega-6 and omega-3 fatty acid, named as PoFAD2 and PoFAD3 responsible for ALA biosynthesis were identified. Then, an ABSCISIC ACID-INSENSITIVE 5 (ABI5) proteins was identified as an upstream transcriptional factor, which activated the expression of PoFAD3 instead of PoFAD2. Moreover, silencing of PoABI5 repressed the response of PoFAD3 to ABA. This study provides the first view on the connection between the function of ABA signaling factors and ALA biosynthesis in the P. ostii seed, which lays the foundation for studies on the regulatory mechanism of ABA signaling involved in the UFAs synthesis during seeds development, meanwhile, it will shed light on manipulation of ALA content for satisfying human demands on high quality of edible oil or healthy supplement.

Fatty Acid Composition, Phytochemistry, Antioxidant Activity on Seed Coat and Kernel of Paeonia ostii from Main Geographic Production Areas.

Paeonia ostii is an important woody oil plant cultivated in China on a large scale. Its seed oil is enriched with unsaturated fatty acids and a high content of alpha-linolenic acid (ALA), which are beneficial to human health. The aim of this research is to determine the qualitative traits characteristic of P. ostii seed from various production areas in China. In this study, seed quality traits were evaluated on the basis of proximate composition, content of fatty acids, tocopherol, secondary metabolites, and the antioxidant activity of seed coat (PSC) and kernel (PSK). A high content of total fatty acids (298.89-399.34 mg g-1), crude protein (16.91%-22.73%), and total tocopherols (167.83-276.70 µg g-1) were obtained from PSK. Significant differences were found in the content of palmitic acids (11.31-14.27 mg g-1), stearic acids (2.42-4.24 mg g-1), oleic acids (111.25-157.63 mg g-1), linoleic acids (54.39-83.59 mg g-1), and ALA (99.85-144.71 mg g-1) in the 11 main production areas. Eight and seventeen compounds were detected in PSC and PSK, respectively. A significantly higher content of total phenols was observed in PSC (139.49 mg g-1) compared with PSK (3.04 mg g-1), which was positively related to antioxidant activity. This study indicates that seeds of P. ostii would be a good source of valuable oil and provides a basis for seed quality evaluation for the production of edible oil and potential ALA supplements from the promising woody oil plant.