Effects Of Melatonin On Swelling Of Lily Bulbs And Application Of Mapk Gene In Promoting Growth Of Lily

Lily（Lilium spp.）is a popular bulbous flower,commonly used in potted and cut flower production.However,lily bulbs in China are basically dependent on imports from Netherland,which seriously hinders the development of lily industry.Development of techniques for promoting lily bulb expansion and characterization of bulb development mechanisms are important to achieve the local bulb production in China.In this dissertation,the role of new plant hormone melatonin in lily bulb tissue culture and substrate culture was investigated.The optimum hormone mixture formula to increase the number of bulblet and promote bulblet enlargement was screened.The technology combining fertilizer and water management with melatonin treatments during substrate cultivation was established.Furthermore,the preliminary study of MAPK gene in lily bulb enlargement was carried out.The results are as follows:1.Effect of melatonin on lily bulblet induction during tissue culture.The results showed that 10^-9-10^-7mol/L MT could promote the induction of lily bulblets and significantly increase the number of induced bulblets during tissue culture of two lily varieties,’Siberia’and’White Heaven’.The optimal concentration of melatonin for inducing bulblets of the two varieties of lily was 10^-7mol/L and 10^-9mol/L,respectively,and the number of induced bulblets was 2.75 and 2.53,respectively.NAA at 0.1-0.2 mg/L promoted the induction of’White Heaven’bulblets.Compared with the optimal concentration of NAA at 10^-6mol/L,melatonin exhibited better induction efficiency for bulblets production at low concentration.2.Effect of melatonin on lily bulblet development during tissue culture.The results showed that 10^-9-10^-7mol/L melatonin could promote the expansion of bulblets of two varieties of lily,and significantly increase the expansion rate of tissue culture bulblet during tissue culture.The optimum melatonin concentration to promote bulblet development is 10^-9mol/L.The expansion multiples of bulblets were4.39 and 3.82,respectively.3.Effect of melatonin and yeast metabolites treatment on lily bulb growth in greenhouse.The results showed that the application of 500-fold dilution of yeast metabolites could effectively promote the expansion of the two cultivated lily varieties bulb.Combined treatments with 10^-9-10^-7mol/L melatonin with 500-fold dilution of yeast metabolites effectively effectively promote the expansion of lily bulbs.The optimal concentration of melatonin for the two lily varieties bulb growth is 10^-7mol/L.After treatments,the fresh weight and circumference of’Siberia’and’Conca d’Or’lily bulbs were significantly higher than that of the control.4.Functional cloning of expansion related gene LiMAPKs and application in lily tissue culture.The expression levels of LiMAPK9 and LiMAPK15 genes showed a gradual downward trend during tissue culture bulblet growth,and exhibited significant down-regulationt after melatonin treatment.The full-length coding region of the two genes was cloned,and heterologously transformed into Arabidopsis.It was found that the number of rosette leaves,plant diameter,leaf length and leaf width of T2 transgenic Arabidopsis were significantly increased when compared with wild type at 30 days after planting.In summary,the results showed that melatonin has promoting effects on bulblet induction,bulblet enlargement during lily tissue culture,and alleviating bulb deterioration in greenhouse condition.Relevant research provides technical assistance for obtaining high-quality bulbs and the promoting bulb expansion using tissue culture technology in the future.LiMAPKs transgenic plants showed improved growth,thereby providing theoretical basis for further characterization of the mechanism of MAPK cascade signaling pathway regulating lily bulb development.