Studies On Establishment Of Regeneration System And Polyploid Induction Of Lagerstroemia Indica

Lagerstroemia indica,flowering in summer for a long period,is one important species of ornamental plants,which still presents some problems in landscape application,such as lack of varieties with larger and denser flowers.Polyploid,with enhanced resistance,possesses larger colorful flowers. Polyploid breeding has been applied in new varieties cultivating of ornamental plants widely.However, it is in the initial stage of L.indica breeding.Research on L.indica 'Xiao Hua Zi' 'Supersonic','Bicolor' and L.subcostata have not been reported.In this paper,colchicine was used to treat seeds, seedling growth point,adventitious buds and callus of the mentioned species for polyploid inducing. Combined with morphological features and stomate size flow cytometer was used to identify the polyploid.The results are as follows:1.The regeration syetems of L.indica and L.subcostata were established.In callus inducing,the optimal medium for L.indica 'Xiao Hua Zi' was 1/2MS+6-BA1.0mg/L+2,4-D 0.5mg/L,inductivity is 38.33%.The optimal medium for L.indica 'Bicolor' was 1/2MS+6-BA1.0mg/L+2,4-D 0.2mg/L, inductivity is 70.48%.The optimal medium for L.subcostata was 1/2MS+6-BA1.0mg/L+2,4-D 0.5mg/L,inductivity is 46.18%.In callus differentiation,the optimal medium for L.indica 'Xiao Hua Zi' was 1/2MS+6-BA2.0mg/L+IBA 0.2mg/L,differentiation rate is 50.6%.The physiological state of leaves influenced regenerating.Using the leaves of adventitious buds of L.indica 'Xiao Hua Zi' for callus induction,inductivity is 88.33%.The establishment of regeneration system laid a foundation for polyploid inducing and chimeral isolating and stabilizing.2.Treated the seeds and grwth point with colchicine for polyploid inducing.Study shows that different species are in different level of sensitivity to colchicine,the optimal treatment(the concentration of colchicine and the processing time) is different relatively.Comparatively,L.indica 'supersoinca' is the most sensitive one.The variability of seeds was 65.77%treated by 0.8%colchicine for 2 days.The variability of growth point was 66.67%treated by 0.5%colchicine for 2 days.L. subcostata is the lest sensitive one.The variability of seeds was 35.49%treated by 1.0%colchicine for 4 days.The variability of growth point was 54.17%treated by 0.5%colchicine for 3 days.Colchicine treat growth point,with low mortality,was the better polyploid inducing method.3.Treated the adventitious buds and callus with colchicine for polyploid inducing.The adventitious buds treated by 0.6%colchicine for 24hours,the variability of L.indica'Bicolor' was 22.22%,and L. subcostata was 18.75%.The mortality is growing as the processing time increased.In order to obtain higher variability and lower mortality,the treatment of high concentration and short processing time should be adopt.The mortality of L.subcostata callus was 41.67%treated by 0.1%colchicine for 18 hours.Inoculated the callus to the medium with 800mg/L colchicines for 40 days,the mortality was 43.33%reaches to median lethal dose.800mg/L was the ideal concentration of colchicines in this method for L.indica'Bicolor'.4.Optimized the system of chromosomes preparation.Sprouting leaves were the ideal material. The optimal chemical for dissociation was the mixture of concentrated hydrochloric acid and alchol (HCl:alchol=1:1).Used the colchicines pretreated the sprouting leaves of L.indica for 3-5 hours were the better method.The optimal time for dissociation of L.indica 'Supeisonic' was 50-65min,and L. indica 'Xiao Hua Zi' was 25-35min.Used the 8-hydroxyquinoline pretreated the sprouting leaves of L. subcostata for 5 hours were the better method.The optimal time for dissociation was 60-70min. Optimization of the system of chromosomes preparation laid a foundation for karyotype analysis and relative reaserch.5.Flow cytometer was used to identify the variable plants.Used the 8-hydroxyquinoline pretreated the leaves for 3 hours,then prepared the nucleus suspension of L.indica with Lysis buffer and L. subcostata with Otto buffers which add 1%PVP.Determine the nucleus suspension of the variant strain with flow cytometer.Result shows that there were 9 strains L.indica 'Supeisonic' and 3 strains L. subcostata whose fluorescence value were doubled,whether to be tetraploid need further evidences.This paper provide theoretical basis for rengeneration system of L.indica,laid foundation for polyploid breeding of Lagerstroemia.