Abstract
The safflower (Carthamus tinctorius L.) is a multipurpose crop which has been used for production of oil, dye and medicine for about 4,500 years. Nowadays it is mainly grown as a source of oil which contains a high proportion of linoleic acid, but recent research has revealed that its petals possess marked antioxidant potential. The genus Carthamus comprises at least 25 species and subspecies of which only one, C. tinctorius, is cultivated. According to cytogenetic studies, the strongest candidate for the ancestor of the cultivated safflower are considered to be C. oxyacantha or C. palaestinus, and the genus is divided into four sections based on chromosome numbers, namely, Section Ⅰ 2n=24 diploid species with a BB genome including the cultivated species, SectionⅡ 2n = 20 diploid with an AA genome, Section Ⅲ 2n =44 tetraploid with an AABB genome and Section Ⅳ 2n = 64 hexaploid with an AABBAA genome. Our recent molecular phylogenetic analyses based on the sequence variation in the nuclear-encoded SACPD gene have revealed that the ancestor of the cultivated safflower is actually C. plaestinus, indicating that the origin of safflower is the Near East. Furthermore, based on our results we proposed a new hypothesis of evolution of Carthamus, that is, tetraploidy resulted from hybridization between XX and YY genome unknown or extinct diploid species and hexaploid forms by hybridization of XXYY tetraploid species with an AA genome diploid species. With respect to world safflower germplasm, it has been reported that cultivars have diverged geographically. Our study based on AFLP (Amplified Fragment Length Polymorphism) analysis indicated that the Asian safflower cultivars can be divided into two groups, namely the East Asian group and the other Asian group, which is consistent with previous reports. In Japan, the safflower has been used for extraction of dye historically and even today. The Yamagata area has been the producing center of safflower in Japan from the Edo period. In the late Edo period (18–19 century) the Yamagata brand safflower “Mogami-benibana” was traded in Kyoto and Edo with a high price. After the Edo period, safflower production was discontinued in Yamagata, but in the latter half of 20th century it were restored and Yamagata Prefecture bred a variety of “Mogami-benibana” from a handful of safflower seeds discovered in a farmer's house. Our molecular phylogenetic analysis revealed the recent Mogami-benibana to belong to the East Asian group, with close similarity to Korean safflower cultivars. These results indicated that recent Mogami-benibana is direct progeny of previous Mogami-benibana in Edo period and was derived from Korea and originally came from the Near East throughout the Silk Road. Our studies also revealed Mogami-benibana has intra-varietal variation at both morphological and DNA levels. Investigation of morphological traits suggested that world safflower germplasm features a high level of variation in agricultural traits such as flowering day, plant height, and numbers of capitula and seeds, but some of these traits may be seriously affected by environmental conditions such as the weather. Through our studies, the potential for breeding of new safflower varieties, including examples with high petal yield, was reconfirmed.
