Study On Triploid Induction And Variation Of Traits In Eucommia Ulmoides Oliver

Eucommia ulmoides is an important temperate species because it contains Eucommia rubber,iridoids,and other medicinal substances.In the present study,Eucommia was employed as polyploid breeding materials,in order to solve the problem of low rate of triploid induction.The the development of female gametes in Eucommia ulmoides,artificially induced megaspore and embryo chromosome doubling technology,as well as genetic variations of growth,photosynthetic physiology and the main efficacy of components in induced triploids were conducted by combining the reproductive biology,gamete chromosome doubling and molecular marker techniques.The results will provide a platform for the polyploid breeding of Eucommia.The main results are described as following:1.Based on the understangding of meiotic law of megaspore mother cells(MMCs),the optimal treatment conditions for megaspore chromosome doubling induced by high temperature exposure to produce triploid in Eucommia ulmoides was established.Based on the relationship between the meiotic stages of MMCs and the number of days in which the male flowers released pollen,38 triploids were produced by megaspore chromosome doubling induced with high temperature exposure when combined the external mrphological markers of female flower buds.2-3 days after pollen grain released,female buds were treated for 4 hours by 45? high temperature was the optimal treatment conditions for inducing megaspore chromosome doubling and 5.45%.triploids were produced.This was corresponding to the time point that the edge of the stigma began to wilt and the meiotic stage of MMCs varied from pachytene to diplotene.2.The optimal treatment conditions for create triploids by inducing embryo sac chromosome doubling with high temperature treatment were studied,and 6 triploids were obtained by embryo sac chromosome doubling for the first time.The relationship between the developmental period of embryo sac and the size of female buds and duration of pollen releasing in anthers were understood,and the optimal technique for induction of embryo sac doubling by high temperature exposure was established.The length of flower buds ranged from 1.83cm to 2.72cm 6-10 days after pollen released in the male plants,in which the developmental period was uni-uncleate,two-uncleate and four-uncleate embryo sac.The highest induction rate of triploid would arrive at 11.1%when using 48? to treat female buds for 4-6 hours.3.The main reason for the low triploid production rates by induced megaspore and embryo sac chromosome doubling with high temperature was proofed.In the process of development of fixed female flower buds,which were induced by high temperature treatment,the asynchronous meiosis of MMCs or developmental stage of embryo sac development among different female buds was significant.The reason is that the sampled research materials in this experiment have not yet been cloned,and the high temperature treatment can only be carried out in the outdoor.Female buds derived from different plants and different positions of the same plant were affected by genotypes and environmental change.Owing to the asynchronous development of most female flower buds,chromosome doubling was not induced timely,which was the main reason for the low triploid production rate.4.The SSR markers were used to identify the male parents of obtained triploids and the 2n gametes of FDR or SDR.Using 10 pairs of SSR markers which could be used to amplify the stable and significant differences bands ultimately to identify the male parent of the 31 triploids,including 25 derived from megaspore chromosome doubling and 6 derived from embryo sac chromosome doubling.The 25 triploids derived from megaspore chromosome doubling,were analyzed by using 6 SSR markers with low recombination frequencies,and 12 triploids originated from FDR 2n eggs and seven triploids originated from SDR 2n eggs were identified.5.Triploid showed a certain advantage over diploids in vegetative growth,stomatal traits,leaf characteristics,photosynthetic index and secondary metabolites.The results showed that the triploid plants which grew in the same growth condition did,compared to the diploid control,have obvious advantages in growth.The average height and DBH of the triploid plants were 2.41m and 1.4cm,respectively,which were 16.99%and 19.09%higher than that of the diploids,the average leaf area and leaf thickness of triploid plants were 280.36cm2 and 449.43?m,which were 45.8%and 27.8%larger than that of the diploids.The leaf size and photosynthetic rate of triploids were higher than those of diploid control plants,which was the main reason for the advantage of triploid in vegetative growth.The content of chlorogenic acid,geniposide,geniposide acid and aucubin in triploids were better than that of its diploid half-sibling families.It is shown that polyploid breeding had great potential for exploitation and utilization Eucommia.Heterosis can not be obtained by distant hybridization because Eucommia is the single specie of the Eucommia genus in the Eucommiaceae family.