Research Of Regeneration In Vitro And Simulated Abiotic Stress Tolerance Of Autotetraploid Lilium Davidii Var. Unicolor And Lilium Pumilum DC. Fisch.

Polyploidization is of great significance for improving flower quality and plant resistance.Lilium davidii var.unicolor and Lilium pumilum DC.Fisch.have high economic value in ornamental,edible and medicinal purposes.The autotetraploid seedlings were previously induced in vitro from the above-mention diploid Lilium by our research group.In order to realize the wide application of the new polyploid germplasm in Lilium in production practice,it is of great significance to clarify the growth characteristics and obtain a large number of excellent trait materials with ploidy stability.This research take the diploid and its homologous polyploid tissue culture seedlings of Lilium davidii var.unicolor and Lilium pumilum DC.Fisch.as test materials.To explore the differentce of from diploid and autotetraploid Lilium on the induction of adventitious buds and somatic embryos from scale explants.Drought and saline-alkali stress were simulated with different concentrations of?0,3,6,9,12%?PEG and(5,10,15,20 mmol·L^-1)Na HCO₃,respectively.To research the difference of response of diploid and autotetraploid Lilium to abiotic stress.For the purpose of to provide theoretical basis for breeding and selecting the new polyploid germplasm in Lilium with excellent charactes,the results showed that:1.The induction rates of adventitious buds and somatic embryos regenerated from diploid and autotetraploid Lilium were over 91%.Compared with diploid seedlings,it took shorter time for the tetraploid plant in responding to greening,budding and produce embryogenic callus or somatic embryos from the scales.The tetraploid scales produce adventitious buds with plump and large bulbs,and morphogenesis of somatic embryos are clear and maturity.The regenerated plants induced by tetraploid showed stable ploidy and high survival rate.2.With the increasing of PEG stress concentration,the growth indicators,RWC and stomatal size of the leaves of these two different ploidy lilies decreased significantly,while the maximum length and the fresh weight of roots increased significantly under 3%-9% PEG treatment.On the 8th day of applying 6% PEG stress,the diploid seedlings showed drooping leaf tips and yellow leaves,while the tetraploid seedlings remain robust with dark green leaves.Under 6% PEG treatment,chlorophyll content of leaves decreased significantly in diploid Lilium,and the content of MDA,proline and SOD activity increased significantly.However,the variation range of growth and physiological indexes of tetraploid seedlings was always small,did not changes significantly.Under moderate stress,the tetraploid stomata size decreased significantly and gradually closed.Under 12% PEG treatment,the growth of tetraploid plants was better than that of diploid plants.And the proline content and SOD activity of the tetraploid lily increased significantly and were significantly higher than that of diploid lily.The MDA content of tetraploid lily was always lower than that of diploid lily.3.With the increasing of Na HCO₃ stress concentration,the growth indexes of these two different ploidy lilies decreased significantly.Root growth of tissue-cultured seedlings isseverely restrained in saline-alkali stress.On the 8th day of applying 10 mmol·L^-1Na HCO₃ treatment,the diploid lily leaves were yellowing and wilting,alkaline-salt damage index increased significantly,while the tetraploid seedlings leaf tip was yellowish and grew well.Under 10 mmol·L^-1 Na HCO₃ treatment,tetraploid lily maintained high chlorophyll content and relative water content of leaves,and the stomatal size of decreased significantly.Howere,the stomatal opening degree of diploid is large,resulting in serious water loss.Under 20mmol·L^-1Na HCO₃ treatment,the proline content and SOD activity of the tetraploid seedling sincreased significantly and were significantly higher than those of diploids,while the MDA content of tetraploids was significantly lower than that of diploids.In conclusion,compared with diploid seedlings,autotetraploid Lilium can improve the regeneration efficiency and can enhance the drought and saline-alkali stress tolerance.