Researches On Core Collection Construction Of Germplasm Of Indigenous Poplar Species In Hubei

Poplar is a group of important timber tree species around the world and the poplar cultivation area in China is the largest in the world. Hubei province is an important poplar growing area. There are abundant indigenous poplar resources in Hubei, but no systematic research on germplasm resources has been made. In this article, indigenous poplar germplasm in the distribution areas in Hubei province were investigated, samples were collected. Then, by applying ISSR molecular markers, researches on genetic diversity of the germplasms were carried out. Finally, a core collection of indigenous poplar germplasm was constructed. Main purpose of this research was to provide scientific basis for the protection and utilization of the indigenous poplar germplasm resources in Hubei province. The results are of great theoretic and practical value for the development of poplar industry in Hubei province. Main results were as follows:1. Resources investigation was carried out in Yichang and Enshi, the most concentrated indigenous poplars distribution region, and217indigenous poplar germplasm samples were collected, including7poplar species, i.e. P. lasiocarpa, P. tomentosa, P. adenopoda, P. davidiana, P. simonii, P. ningshanica and P. alba.2. Seventeen highly polymorphic ISSR primers were screened out for genetic diversity analysis of P. lasiocarpa, P. tomentosa, P. adenopoda and P. davidiana and the genetic diversity indexes were calculated by using POPGEN32software. Results showed that, the percentage of polymorphism locis of four poplar species were all higher than97%. The genetic diversity indexes Na, Ne, H and I of P. tomentosa were1.9926,1.4959,0.2967and0.4534respectively; the Na, Ne, H and I of P. adenopoda were respectively1.9771,1.5248,0.3188and0.4729; the Na, Ne, H and I of P. davidiana were respectively1.9758,1.5520,0.3251and0.4901; the Na, Ne, H and I of P. lasiocarpa were respectively1.9771,1.4662,0.2798and0.4362. All the indexes showed that these four species of poplar have quite high level of genetic diversity. 3. Population genetic structure and genetic differentiation of the4poplar species were analyzed and the variation is not same among populations. According to the genetic distance, UPMGA cluster analysis on populations was made for each poplar species and the results showed that there were no obvious correlation between population genetic distances and geographical distribution. Mantel test also verified this result.4. Based on the results of analysis on genetic diversity and by using NTSYS, POPGEN32and SPSS software, core collections of P. lasiocarpa, P. tomentosa, P. adenopoda and P. davidiana germplasm were constructed respectively through stepwise clustering with random sampling method. For P. tomentosa,19samples were screened out to construct the core collection, the sampling rate was31.1%; for P. adenopoda,9samples were screened out to construct the core collection, the sampling rate was about33.3%; for P. davidiana,9samples were screened out to construct the core collection, the sampling rate was42.8%; for P. lasiocarpa9samples were screened out to construct the core collection, the sampling rate was33.3%. Based on the observed number of alleles, the effective number of alleles, Shannon’s information index and Nei’s genetic diversity index, t-test on genetic diversity between the original collection and core collection of the four poplar species was carried out. The results showed that there were no significant differences in genetic diversity between the core collection and primary collection, indicating that the core collections could represent the genetic diversity of the primary collections.5. A core collection of indigenous poplars containing56samples was constructed by combining the primary core collection of P. lasiocarpa, P. tomentosa, P. adenopoda and P. davidiana, and all the samples of P. simonii, P. ningshanica and P. alba.