Ecotopic over-expression of PoCHS from Paeonia ostii altered the fatty acids composition and content in Arabidopsis thaliana.

Chalcone synthase (CHS) is the key enzyme in the flavonoid biosynthetic pathway and has been studied in many plants, but the function of the CHS gene has not been well characterized in Paeonia ostii. In this study, we obtained a CHS homolog gene from P. ostii, which possessed the putative conserved amino acids of chalcone synthase by multiple alignment analysis and demonstrated the highest expression in developing seeds. In vitro assays of the recombinant PoCHS protein confirmed enzymatic activity using malonyl-CoA and 4-coumaroyl-CoA as substrates, and the optimal pH and reaction temperature were 7.5 and 40 °C, respectively. Furthermore, ectopic over-expression of PoCHS in Arabidopsis up-regulated the expression levels of genes involved in seed development (ABI), glycolysis (PKp2, PDH-E1a, and SUS2/3), and especially fatty acid biosynthesis (BCCP2, CAC2, CDS2, FatA, and FAD3). This resulted in an increased unsaturated fatty acid content, especially α-linolenic acid, in transgenic Arabidopsis seeds. In this study, we examined the functions of CHS homolog of P. ostii and demonstrated its new function in seed fatty acid biosynthesis.

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.