| Neillia thyrsiflora belongs to the family Rosaceae. Its panicle is 6–15.5 cm in diameter with white, pink or pale pink and so on. It is a beautiful ornamental tree species and widely distributed in the Qinling Mountains. Neillia thyrsiflora is gathered in the wild,and mainly sired by sprout breeding. Form the test on the seeds germinate we found that the germination rate is very low and seed propagation is poor. In this study, tissue culture was used to solve the problem of seed breeding of Neillia thyrsiflora, which provide technical support for large number of applications in future landscaping. The living environment of Neillia thyrsiflora has been serious damaged, which caused a sharp reduction in populations of Neillia thyrsiflora or even endangered. In this work, 6 natural populations of Neillia thyrsiflora were analyzed by AFLP to investigate the genetic diversity and population genetic structure, which provided a theoretical basis for the conservation and utilization of Neillia thyrsiflora. In this study, the following conclusions:1、Established the rapid propagation system in vitro of Neillia thyrsiflora. The study indicated that MS+6-BA 1.0 mg·L-1+NAA 0.2 mg·L-1was the suitable medium for explants induction of cluster buds; MS+6-BA2.0mg·L-1+NAA 0.2mg·L-1 was the optimizing medium for multipropagation, and its average proliferation coefficient reached 7.5; the optimal rooting medium of shoots was 1/2MS+ BA 0.2 mg·L-1, the rooting rate could reach to 66.7%.2、The primer screening test showed that four primer combinations(M-CTC/E-AG, M-CTA/E-AG, M-CAT/E-ACT, M-CAA/E-ACG) were selected form 64 selective primer combinations, which successfully produced clear high-intensity and reproducible high polymorphism bands. The selected primers produced 283 bands, the majority(86.57%) polymorphic. The minimum and maximum number of bands was 53 and 103,70.75 in average.3、Intra-population genetic variability was higher(56%) than inter-population diversity(44%). It shows that genetic variation was produced both within populations and among populations. Variation within populations was the main sources of variation. The Neillia thyrsiflora population from Huangbaiyuan presented the highest percentage of polymorphic loci(33.92%), followed by that from Guguan(28.98%). The lowest was from Meixian(10.95%). Nei’s genetic distances(h) ranged from 0.0481 to 0.1223 and Shannon’s index(I) ranged from 0.0688 to 0.1841. Across all populations, populations from Huangbaiyuan had the highest level of gene diversity, while those from Meixian showed the lowest diversity. POPGENE analysis showed that the Neillia thyrsiflora had higher genetic diversity at species level(PPL=84.10%, H=0.2213, I=0.3490) compared to population level(PPL=22.58%, H=0.0855, I=0.1269).4、The Neip’s genetic identity and genetic distance calculated by POPGEN was used for further analyzing. The genetic identity ranged from 0.7614 to 0.8879 in the six populations of Neillia thyrsiflora. And the genetic distance ranged from 0.1188 to 0.2726. Among them, the populations between Huangbaiyuan and Zhouzhi had highest genetic identity, but had the lowest genetic distance. While the lowest genetic identity existed between Meixian and Taibai. The genetic similarity coefficient calculated by NTSYS-pc 2.11 among 6 populations was between 0.79 and 0.91. And UPGMA clustered the investigated populations together according to the threshold value at 0.79. |
PDF Full Text Request