Immunoadjuvant saponin production in seedlings and micropropagated plants of Quillaja brasiliensis

Abstract

The leaves of Quillaja brasiliensis, a native tree species of southern Brazil, accumulate saponins which have adjuvant activity in vaccines. An efficient micropropagation system for Q. brasiliensis was developed. Plants were obtained from aseptically germinated seeds. High rates of germination were observed on filter paper and aseptic medium substrate (sucrose and light exposure did not affect the germination response). Stem nodal segments were inoculated into Murashige and Skoog (MS) medium supplemented with 6-benzylaminopurine. Each explant produced multiple shoots, which elongated satisfactorily on the same medium. Elongated shoots were rooted in a modified MS medium with or without auxins. Best rooting responses were observed in medium containing 10 mg l−1 indole-3-acetic acid under continuous exposure. The rooted explants were acclimatized and successfully transferred to soil, yielding approximately 95% survival after 10 mo. Leaf content of immunoadjuvant saponins in micropropagated plants was not affected by auxin type used for rooting and was comparable to that of field-grown trees. The results indicate that Q. brasiliensis represents an alternative and readily renewable source of biomass for the production of bioactive saponins.