Studies On Mechanisms Of Molecular Response To Heat Stress And Genetic Transformation Of Lilium Sulphureum

As one of the six major cut flowers,lily?Lilium spp.?prefers cool environment and can withstand low temperatures,but its heat tolerance is poor.At present,the suitable temperature for the growth and development of the main lily cultivars in China is 16-24°C,and it is inhibited above 30°C.However,the high temperature over 35°C often occurs in summer in our country,which reduces the quality of cut flowers and causes bulb degradation,restricting the year-round production of lily.Given this,breeding heat-resistant lily varieties is the key factor to solve the problem.China is blessed with lily resources,it is of profound significance to make full use of own resources for breeding heat-resistant cultivars grow well in China.In this study,the heat resistance mechanism of Lilium sulphureum Baker apud Hook.f was researched,and its genetic transformation system was established,which laid a foundation for the research of heat resistance related genes.The main contents were as follows:?1?Detection of heat resistance of Lilium plants.Through field phenology observation statistics,physiological and biochemical indexes determination of Lilium plants,it was found that L.sulphureum was an outstanding heat-resistant germplasm resource,which was suitable for lily heat-resistant breeding.?2?The variation of physiological and biochemical indexes of L.sulphureum in response to heat stress.In order to demonstrate the effect of heat stress on physiological property of L.sulphureum,3-years-old plants were treated by 42?with 0 h,0.5 h,2 h,6 h,12 h,24 h,48 h,72 h and 96 h.The results showed that the relative electric conductivity,MDA and soluble sugar content of the leaves tended to increase with the increase of time;Soluble protein content and POD activity showed a trend of“increase-decrease-increase-decrease”;CAT activity tended to decrease with the increase of time.It showed that 96 h of 42?uninterrupted stress produced irreversible thermal injury effect on L.sulphureum.?3?Analysis of heat resistance mechanism of L.sulphureum.Transcriptome sequencing was performed on 0 h,0.5 h,2 h,12 h and 48 h under heat stress of 42?.By being annotated in GO and KEGG databases,it was found that some physiological and biochemical processes were active under heat stress,such as response to stress,redox process,protein ubiquitination,protein processing in the endoplasmic reticulum,calcium ion binding,metabolic synthesis and so on.Analysis of differential expression genes?DEGs?under heat stress identified a large number of heat response genes,including coding genes related to signal transduction,transcription factors,stress proteins,antioxidant stress,antiosmotic stress and protein ubiquitination.Such as Ca²⁺signal,HSF,MYB,ERF/AP2,b ZIP,Trihelix,MADS-box,b HLH,WRKY,NAC transcription factors family coding genes,HSP,GST,NU6M,GOLS and SKIP27 genes.?4?The establishment and optimization of the genetic transformation system of L.sulphureum.The suitable Hyg concentration for 3,6 and 9 mm³callus resistant screening was 15,30 and 30 mg/L,respectively.The Sterilization concentration of antibacterial agents Cef for 3,6 and 9 mm³callus was 300,350,400 mg/L,respectively.Vector DX2181 which contained GUS gene was introduced into callus by Agrobacterium-mediated transformation.With callus size of 9mm³,Agrobacterium strains of EHA105,pre-cultivation time of 3 d,infection time of 25 min,and co-cultivation time of 5-6 d conditions,the stable transformation rate was the highest.