EN
Safflower varieties were commonly divided into high, low and middle linoleic acid (LA) types according to their LA relative percentage contents in the seed oil. Fatty acid desaturase 2 (FAD2) plays a key role for LA content in seed. The sequence variations of FAD2 (CtFAD2-2, CtFAD2-10, CtFAD2-11) genes which could express in developmental seed of safflower were analyzed in 15 different LA-type materials. The results revealed that the CtFAD2-2 sequences were the same in all materials, and the CtFAD2-10, CtFAD2-11 sequences formed into two haplotypes independent of the LA-type of safflower seed. Yeast expression analysis revealed that two haplotypes of CtFAD2-10 had the function of oleic acid desaturase. The real-time PCR analysis of FAD2 in high and low LA-type materials at different seed developmental stages revealed that CtFAD2-2, CtFAD2-10 and CtFAD2-11 expressed mainly at 10 days after flower (DAF) for two different LA-type materials and the accumulation of few mRNA was detected in 14–22 DAF. The expression pattern of CtFAD2-1 in two different LA-type safflower materials was significantly divergent. For high-LA type, the accumulation of CtFAD2-1 mRNA was extremely low in 10 DAF, and its expression level increased sharply between 14 and 18 DAF and decreased slightly after 18 DAF. For low-LA type, the accumulation of CtFAD2-1 mRNA was extremely low during seed development stages. In conclusion, the gene structure and expression level of CtFAD2-1 may be the main factor affecting the differentiation of LA-type for safflower materials.