Micropropagation with a novel pattern of adventitious rooting in Formosan sweetgum

Abstract

Cultures of the Formosan sweetgum (Liquidambar formosana Hance) were established from axillary buds of intact plants and from petiole segments of in vitro grown leaves. Petiole segments were generally slower than axillary buds to form multiple shoot cultures. Thidiazuron in combination with 6-benzylaminopurine produced on average up to 9.4 shoots per explant. Shoot elongation was significantly affected by the concentration of 6-benzylaminopurine, regardless of auxin addition to the medium. Adventitious rooting occurred up to 90%. An unexpected pattern of adventitious rhizogenesis was observed from the aerial parts of microshoots not in contact with the rooting medium, including leaf blades and petiole axils. In vitro adventitious root formation from the leaf blade was associated with parenchyma cells surrounding the main vein. The regenerated plants established ex vitro did not show any detectable morphological variation and no aerial roots were formed.