In vitro Germination and Seedling Development of Taxus chinensis var. mairei by Embryo Culture

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Taxus chinensis var. mairei is a rare and endangered medicinal plant species distributed in China. In order to promote fast propagation and preserve the natural resources, conditions for in vitro germination and seedling development of embryos of T. chinensis var. mairei from Anhui or Zhejiang were investigated. Results showed that in vitro germination rate of excised embryos cultured under 14 hours photoperiod was higher than that in darkness. But, nearly all embryos germinated under 14 hours photoperiod failed to develop into seedlings. Comparatively, 23.3 and 36.3% of embryos from Anhui and Zhejiang, respectively, which germinated in darkness, developed into full seedlings. Addition of plant growth regulators [gibberellic acid(GA3), indole-3-acetic acid (IAA), 6-benzylaminopurine (BA)] and organic additives (casein hydrolysate and yeast extract) in mediums promoted germination and seedling development. (Woody plant medium) WPM  medium supplemented with 0.5 mg L-1 GA3, 0.5 mg L-1 IAA, 0.5 mg L-1 BA and 1 g L-1 activated charcoal was optimal for the culture of embryos from Anhui, while WPM medium supplemented with 0.5 mg L-1 GA3, 500 mg L-1 casein hydrolysate and 1 g L-1 activated charcoal was optimum for embryos from Zhejiang. Moreover, the germination and seedling survival rate of embryos of T. chinensis var. mairei decreased with increasing maturity of the seeds. In conclusion, darkness during germination is necessary for subsequent seedling development and immature seeds are optimal for embryo culture of this species.