| Rhododendron SPP.is one of ten traditional famous flowers in China which has graceful tree form,beautiful flower color and excellent characteristics of evergreen.It has extremely high ornamental value.Rhododendron is widely distributed in China,which plays an important role in bonsai production,tourism landscape development and landscaping.There are some problems of Rhododendron resources,such as classification system is not clear,naming and classification are chaotic,these problems effect protection of resources and cultivars register.Restricted by the location of Tibetan areas,it is less discussed in the genetic diversity and variation of Rhododendron wild resources.It seriously affected the protection and application of the Rhododendron and hindered the breeding work of Rhododendron.In order to protect the diversity of the Tibetan Rhododendron resources and develop the resources reasonably,and further analyze the diversity and classification of Rhododendron cultivars,the genetic relationship and classification were studied by morphological,ISSR(inter-simple sequence repeats)and AFLP(amplified fragment length polymorphism)markers and the genetic relationship and diversity of Rhododendron located in Tibet were discussed.Main results were obtained as follows:1.Survey and collect the Rhododendron resources.In total of 42 indicators were analyzed,including anatomical structure of leaf and phenotypic traits.R type cluster analysis and principal component analysis were carried out,the most influential traits were chosen,and the most influential characteristics were obtained.2.Genetic relationship of 17 cultivars of Rhododendron was assessed using ISSR markers and AFLP markers.133 bands were obtained by ISSR primers and 129 of which were polymorphic bands;267 bands were amplified by AFLP primer pairs,251 of which showed polymorphism.In the two cluster dendrograms,all of the cultivars were clustered into two major branches,one branch contained the same four cultivars both in ISSR and AFLP,and others is separated into different groups.The results showed that genetic relationship was partially related to their morphological characters especially the flowering phase.3.Genetic relationship of 8 Rhododendron located in Sejila Mountain was assessed using ISSR,a total of 343 fragments were amplified and 335 were polymorphism bands.Eight species were divided into two groups,one is the R.virgatum and R.nivale,and the other are in another group.Combined with its morphological classification,morphological analysis can be used as auxiliary means of related research.4.Genetic diversity of 6 populations of R.triflorum was assessed using ISSR.Eleven ISSR primers were screened successfully,in total of 118 fragments were amplified,114 of which were polymorphic.Percentage of polymorphic loci(PPL)was 63.56%~82.2%,Effective number of alleles(Ne)was 1.282~1.4452,Nei’s gene diversity(h)was 0.1771~0.2645 and Shannon’s Information index(I)was 0.2773~0.4008.The results showed that there is high genetic diversity within populations.The genetic diversity of species level was also high.The result of PPL was 98.31%,Ne was 1.5751,h was 0.3382 and I was 0.5085.The result of AMOVA showed that the genetic variation within populations is the main source of genetic diversity of R.triflorum.The result of cluster showed that genetic distance has no significant correlation with geographical distance.5.Genetic diversity of 6 populations of R.triflorum was assessed using AFLP.Five AFLP primer combinations were screened successfully,in total of 169 fragments were amplified,161 of which were polymorphic.PPL was 52.07%~86.39%,Ne was 1.2079~1.4109,h was 0.138~0.2517 and I was 0.228~0.3887.These results showed that there is high genetic diversity within populations.The result of PPL was95.86%,Ne was 1.5138,h was 0.306 and I was 0.4642 which showed that the genetic diversity of species level was also high.AMOVA analysis showed that the genetic variation within populations is the main source of genetic diversity of R.triflorum.The result of cluster showed that genetic distance has no significant correlation with geographical distance.6.Genetic diversity of 5 populations of R.nivale was assessed using AFLP.Six AFLP primer pairs were screened,in total of 273 fragments were amplified,234 of which were polymorphic.PPL was 58.24%~72.16%,Ne was 1.2316~1.4396,h was 0.1359~0.2639 and I was 0.2123~0.4018.These results showed that there is high genetic diversity within populations.The result of PPL was85.71%,Ne was 1.184,h was 0.273 and I was 0.4151 which showed that the genetic diversity of species level was also high.AMOVA analysis showed that the genetic variation within populations is the main source of genetic diversity of R.nivale.The result of cluster and Mental showed that genetic distance has no significant correlation with geographical distance. |
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