Studies On Genetic Diversity And Constructing Core Collection Of Actinidia Germplasm In Guangdong

The morphological traits and ISSR markers were used as indicators to analyze the genetic diversity and to construct the core collection of 56 Acitinidia germplasms grown in the kiwifruit germplasm nursery in Heping County, Guangdong Province. And Six DNA barcode markers were used to identify five wild species of Actinidia. The results were as follows:1. ANOVA analysis showed a higher diversity in quantitive traits of the kiwifruit plants. The diversities between the wild Actinidia and the kiwifruit cultivars were larger than those between the female and the male Actinidia in the same variety. The Variance Coefficient(VC) showed obvious diversity in fruit’s qualities traits. The principle component analysis suggested that the variation range of the wild Acitinidia was larger than the kiwifruit cultivars.2. Total of 211 loci was detected by PCR amplification of the 16 ISSR markers, of which 152 showed polymorphic with the percentage of polymorphic bands(PPB) 72.04%. The number of allelic(Na) each marker was 1.71 and the effective number of alleles(Ne) was 1.37. The Nei’s genetic diversity(H) was 0.22. The Shannon’s information index(I) was 0.34 and the PIC was 0.87. The principle component analysis based on the ISSR molecular marker suggested that the variation range of the wild Acitinidia was larger than the kiwifruit cultivars, which did not contradict the result from the morphological traits.3. The core collection was selected and evaluated through the principle component analysis, morphological traits and ISSR markers. Comparing the diversity of the morphological traits, the diversity of the ISSR markers, and the reserve percentage of the ISSR amplificates between the core collection and the primary germplasm resource showed that the core collection remains most of the morphological traits, and the reserve percentage of the ISSR amplificates was over 95.7%. The genetic diversity between the selected core collection and the primary germplasm resource was not significant. As a result, 21 germplasms was selected as the core collection of Guangdong kiwifruit.4. The barcode rnL-F and ITS had the most GC content among the 6 barcodes, from 51.1% to 55.2%, while trnH- psbA had the lowest GC content with about 32.0%. NCBI Blast of the above 6 DNA barcode markers showed that the similarity between the 5 Actinidia wild species and those of similar species of Actinidia logged on NCBI were more than 99%, and there were different similarity levels among the different DNA barcodes. The results revealed intraspecific diversity of Actinidia and gene penetration among different species of Actinidia. The ITS marker could be used to identify all the above 5 species of Actinidia according to the NJ(Neighbor-Joining) tree, and the evolutionary divergence among 5 species was obvious according to their ITS sequences. The trnL-F, ITS and matK markers had higher diversity of nucleotide. Based on the sequence analysis with the six DNA markers, ITS barcode was selected as the recommended DNA barcode of Actinidia because of its higher nucleotide diversity and obvious difference among different taxa.