Germplasm Identification Of Pomixis And Establishment Of Embryo Culture System Of Diospyros Lotus L.

In order to realize the efficient breeding of apomixis in Diospyros lotus L.,this study provided technical support for rapid screening and identification of apomixis resources by studying the identification technology of apomixis germplasm resources and the technology of rapid acquisition of apomixis offspring,to shorten the breeding cycle and speed up the breeding process of apomictic reproduction of date plum,provides theoretical basis and practical guidance for date plum breeding,which is of great significance for promoting the healthy development of persimmon industry.The main results are as follows:1.Screening of pollen isolation methods for apomixis of date plum: This study aimed to make a thorough inquiry into the effectiveness of white latex in pollen isolation and provide technical support for apomixis germplasm identification and in-depth analysis of apomixis reproductive characteristics of date plum.Flowers at large bud stage were selected from mature female plants and the corolla was removed carefully to expose the stigma of female flowers on a calm sunny day.Cotton swabs were dipped with appropriate amount of white latex and daubed on stigma of female flowers for pollen isolation and then the stigmas were artificial pollinated at regular intervals.The morphology of stigmas and quantity of pollens on them were observed under the fluorescence microscope,compared with control artificial pollination flowers,to test and verify the feasibility of large-scale or mass application.That is to say,white latex stigma sealing method could effectively isolate female migrating pollen.2.Identification of non-fusion germplasm resources of date plum: In early and middle May,when the female flowers were in the state of large buds,the apomictic reproductive characteristics of 22 date plum plants were identified by white latex pollen isolation method.In late October,after the fruits were fully mature,the statistical analysis was made on the number of fruit set,the quantity of fruit with seeds in it,and the number of seeds in the fruits.The experimental results showed that,12 individual plants with apomixis were identified by white latex pollen isolation method,among which 2 plants had high apomixis rate and 7 plants did not have apomixis at all.Comparative analysis found that there were significant differences between natural pollinated fruits and apomictic fruits,but there were no significant differences in transverse and longitudinal diameters of seeds.3.Establishment of technology for rapid acquisition of apomixis progenies: In order to establish a technology system for embryo culture of apomixis progenies and shorten the process of apomixis progenies breeding.The effects of different embryo development stages（45 d,55 d,65 d,75 d after pollination）and basic media types（MS,1/2MS,（1/2N）MS）on seedling growth were studied.At the same time,the effects of IBA,6-BA and sucrose concentration on embryoid seedling were studied by orthogonal experimental design.The results showed that the operation of embryo extraction at 55 days after anthesis was simple and the success rate was high.The seedling growth of young embryos on 1/2（N）MS medium was better than that on MS and 1/2MS medium,the seedling height was 2.9 cm,the seedling weight was 0.4 g,the lateral root length was 4.32 cm,and the mean lateral root number was 6.32.When the young embryos were inoculated on IBA（0.04 mg/L）+6-BA（0.6 mg/L）medium,the seedlings grew well.After inoculation,all the young embryos could produce lateral roots,and no seedlings without lateral roots occurred.The mean number of lateral roots was 6.42,and the survival rate was as high as 62.7%.4.Rooting,seedling cultivation and transplanting of date plum: in the comparative experiment of dark culture,adding ink in the medium and adding activated carbon in the medium,it was found that dark light culture for 3 days after the inoculation of young embryos had the best rooting induction effect.The average height of tissue culture seedlings was 3.37 cm,the average weight of seedlings was 0.67 g,and the average number of lateral roots was 4.75.At the same time,the seedlings without lateral roots were treated by root cutting.The results showed that the seedlings without lateral roots in embryo culture could be transformed into normal plants by root cutting,and the effective conversion rate was more than 85%.