Materials and methods
2.1. Sample collection
Whole shoots of D. nobile ( Fig. 1a) and mature capsules (Fig. 1b) of D. officinale were collected from Yunnan Province of South Western China in August 2011. Samples were placed in polyethylene bags, labeled, transported to the laboratory and placed in a refrigerator at 4 °C. The mature capsules were surface-sterilized in 70% (v/v) ethanol for 1 min, 2.5% (v/v) NaClO 15 min and rinsed three times in sterile distilled water, opened using a sterile scalpel and the axenic seeds were used for the test of germination and culture of seedlings.