Pinkish-achened form of Taraxacum hybernum Steven – a source of inulin and high molar mass natural rubber

ABSTRACT Taraxacum hybernum Steven (Asteraceae family) native to Southeast Europe is a promising rubber-bearing dandelion species. In the 1930s, several phenotypically distinct forms were described in this dandelion, such as brown-achened and pinkish-achened. More than 70 years after termination of research of temperate zone rubber-bearing plants we were able to find both forms of this species of dandelion in natural habitat. The species is still poorly studied, and there is no information about the differences in the quality and quantity of rubber between brown-achened and pinkish-achened forms. Therefore, the purpose of our study was to analyze the root morphology and yield, the rubber and inulin content, and to determine the molar mass of rubber in brown-achened and pinkish-achened T. hybernum. These two forms of T. hybernum, as well as T. kok-saghyz Rodin and T. brevicorniculatum Korol., were studied. The results show that the root shape most attractive for domestication is typical of brown-achened T. hybernum. The greatest mass of roots was gained for pinkish-achened T. hybernum. The rubber content was about 6% in T. kok-saghyz, 3% in both forms of T. hybernum, and 1.5% in T. brevicorniculatum per dry root mass. Taraxacum kok-saghyz and pinkish-achened T. hybernum turned out to be the leaders in inulin content. Of all four dandelions, the molar mass of rubber was more than 1 million g/mol only for T. kok-saghyz and pinkish-achened T. hybernum. Pinkish-achened T. hybernum is a good alternative for T. kok-saghyz and can be recommended for domestication and cultivation in the temperate zone.