Re-emergence of Lilium callosum Sieb. et Zucc. in Taiwan after a fire allows propagation and renews the possibility of conservation

Background: Lilium callosum is native to Taiwan, but little is known about it since it has been considered extinct since 1915. After the rediscovery of this rare species after a fire in 2011 in Tunghsiao Township, intensive work has been conducted to count the number in the wild population, to develop a conservation strategy, and to understand its reproductive characteristics and even economic potential. Results: To conserve the germplasm of this population, three scales from a wild L. callosum plant were collected to establish a mass propagation system. Flowers from two regenerated plants were crossed by hand-pollination, the ovules were rescued and cultured in vitro, and 10 offspring were obtained. The karyotype was determined to be 2n = 2x = 24 = 2m + 2m(sat) + 2sm + 8st + 10t. The phylogenetic analysis using ITS sequences revealed that the sample of L. callosum from Taiwan was not grouped with the other accessions of L. callosum from other regions. The native habitat is classified as grass-dominated vegetation at the early successional stage and a subtropical monsoon-type climate. To clarify the causes of population scarcity in the native environment, reproductive characteristics of regenerated plants were investigated. Conclusions: Based on the information from this study, it is possible that factors intrinsic to L. callosum could combine to limit pollination and seed formation. The L. callosum pollen only germinated at a temperature that was higher than the native environment, the plants are self-incompatibile, there was a and scarce population, scattered flowering time and dichogamy. Through the culture of these wild harvested parts, the diversity of the germplasm has been broadened and is now available to preserve this rare and valuable species for the future.