芳香堆心菊(Helenium aromaticum)全株具芳香气味, 且头状花序仅含管状花, 是研究菊科植物花香和花型的良好材料, 但目前尚缺乏对其转基因技术体系的研究。为建立高效的芳香堆心菊离体再生体系, 以叶片、茎段和下胚轴为外植体, 进行25组不同激素及不同浓度配比的不定芽诱导研究。结果表明, 以芳香堆心菊叶片为外植体, 培养基为MS+ 0.2 mg·L^-1 NAA+1 mg·L^-1 6-BA+0.2 mg·L^-1 TDZ, 培养20天后愈伤组织诱导率高达100%, 丛生芽的诱导率为62.10%; 将不定芽接种于1/2MS培养基中进行生根培养, 16天即可生根, 且生根率为63.33%; 生根后继续培养14天现蕾, 开花率达93.33%。此外, 研究表明芳香堆心菊的再生受外植体来源、激素种类和浓度的影响。2,4-D不利于芳香堆心菊不定芽的诱导, 适宜浓度的6-BA和TDZ组合能有效促进芳香堆心菊不定芽的形成。研究初步建立了芳香堆心菊组织培养条件下的离体再生体系, 为建立其遗传转化体系奠定了坚实的基础。研究结果还可用于后续有关菊科植物花香和花型的研究。

Helenium aromaticum has a fragrant odor and its capitulum contains only disk flowers. H. aromaticum is a good model for studying development of floral patterns in Compositae. However, methods for genetic transformation of H. aromaticum is currently not available. In this study, we report the establishment of an efficient in vitro regeneration system of the H. aromaticum. The induction of adventitious buds was tested with various combinations and concentrations of 25 different phytohormones by using leaves, stem segments, and hypocotyls as explants. We found that when leaf explants were cultured on MS medium supplemented with 0.2 mg·L^-1 NAA, 1 mg·L^-1 6-BA, and 0.2 mg·L^-1 TDZ for 20 days, the induction of callus was 100% and the induction rate of adventitious buds was 62.10%. The newly-formed adventitious buds were then cultured on 1/2MS medium for 16 days and the rooting rate reached 63.33%. After culturing for an additional 14 days, floral buds initiated and eventually flowering with a rate of 93.33%. In addition, we also found that the regeneration of H. aromaticum was affected by the nature of explants, the types and concentrations of phytohormones. Whereas 2,4-D is incapable of inducing adventitious buds, the combination of appropriate concentrations of 6-BA and TDZ effectively promotes the formation of adventitious buds of H. aromaticum. This study has established an in vitro regeneration system of H. aromaticum, which is a key perquisite for the subsequent establishment of its genetic transformation system. Moreover, this method will also be an important reference for studies on the floral development patterns in Compositae.