The establishment of a slow-growth conservation system in vitro for two wild lily species
There are abundant resources of wild lily in China. To achieve a sustainable use for these resources, a slow-growing preservation system should be well established. Therefore, to get an optimal storage condition, tube seedlings of Lilium davidii and Lilium longiflorum were used as explants cultured on nine different media at 24 and -2°C separately, which included: 1/4 or full Murashige and Skoog medium (MS) with 3, 6 or 9% sucrose, 1/4 or 1/2 MS with 1.0 or 3.0 mg/L abscisic acid (ABA). During the storage, the spout growth, and multiplication rate were measured every month. Results show that the growth restriction degrees for both species were related to the four factors (MS content, the concentration of sucrose and ABA, temperature). The inhibitory effect was more obvious at -2°C. At 24°C, the medium should be replaced every three to four months; otherwise the contamination rate would rise with the extension of storage time. At -2°C, the 1/4 MS with 9% sucrose or 3.0 mg/L ABA (M3A) were more effective, especially the latter one. The M3A played the greatest inhibitory effect on height growth of the two lily species, on which both species had been conserved on the original medium for more than 15 months. The tube seedlings conserved for 15 months could turn to normal plantlets after re-growth for one month which showed no obvious difference in morphology. 87.5% plantlets planted in peat could survive. In conclusion, the promising conservation condition was M3A at -2°C which was suitable for mid-long term preservation of lily germplasm resources.
Key words: Lily, wild species, slow-growth, conservation.