Genetic Diversity Of Armeniaca Cathayana Based On SSR And ISSR Analysis

Armeniaca cathayana D. L. Fu et al., a species of Rosaceae Subfam. Prunoideae Armeniaca Scop., has important economic values, wide development and utilization prospect because of its thin endocarps, sweet kernels, and sources of high quality oil. A. cathayana has high ecological benefit and social benefit for "Pioneer" species in drought-resistance and "green bank" in hills,mountains and sand area.The molecular genetics of A. cathayana has not seen so far. Based on 48 germplasm (36 kernel-apricot) and 24 hybrid experimental materials of A. cathayana, and 14 related experimental materials, 2 of A. sibirica, 10 of A. vulgaris, 1 of A. elongata, sp. nov. ined. and 1 of aprium, this paper using SSR and ISSR molecular markers takes the lead in investigating the genetic relationship, genetic diversity, hybrid offspring variation of A. cathayana. The genetic diversity of the species were analysed through cluster analysis, principal component analysis and genetic variation coefficient analysis, which can provide scientific basis for the breeding and genetic improvement of A. cathayana. The results showed that:(1) Through the scientific experiments in DNA bands display of Armeniaca Scop., the paper proposed a new DNA bands display technology of Microsatellite DNA, which called Fluorescent Imaging Technology. Compared with Silver Stain Technology, the main technology of microsatellite DNA band display so far, the new technique has more advantages, such as high resolution, efficient, simple and clear, and clear background. Fluorescent Imaging Technology is a new DNA bands display technology worthy of popularizing in the laboratory.(2) Using SSR molecular markers, this study investigated the genetic relationships among the species of A. cathayana, A. vulgaris and A. sibirica. Research results showed that A. cathayana had farther genetic relationship with A. vulgaris and A. sibirica, which provided evidence to the morphology classification of A. cathayana from DNA level. Dabianxing-apricot had closer genetic relationship with A. cathayana and farther genetic relationship with A. vulgaris and A. sibirica, so it should belong to variation groups of A. cathayana, not variation groups or hybrids of A. vulgaris and A. sibirica in molecular level. (3) The genetic diversity of 47 A. cathayana germplasm experimental materials were studied using SSR and ISSR markers. The results showed that: Using SSR molecular markers, a total of 65 alleles(Na)were detected, the polymorphisms rate (PPB) was 100%, and the genetic similarity coefficient ranged from 0.4769 to 0.9846. Using ISSR molecular markers, a total of 92 alleles(Na)were detected, the polymorphisms rate (PPB) was 80.43% and the genetic similarity coefficient ranged from 0.5978 to 0.9891. These results suggested that there was rich genetic diversity of A. cathayana.(4) Six primers with parents complementary belt type were selected by using SSR molecular marker technology, which can be used to discern true or false hybrids. Research results showed 22 of 24 hybrid maerials of six hybridized combinations of A. cathayana can be identified as true hybrids except two hybrids can not be identified. In addition, cluster analysis, genetic relationship and genetic variation analysis results showed that six combination hybrids displayed high consistency and not significant genetic diversity.(5) Using ISSR molecular markers it was studied that the heterosis prediction of A. cathayana parents and hybrid materials in three hybrid combinations. The results showed that the genetic similarity coefficient between hybrids and their parents were lower than their parents, but the hybrids were higher than the parents in alleles, expected alleles, expected heterozygosity and shannon diversity index. These showed hybridization could improve genetic diversity level of A. cathayana obviously and produce some new cultivars with potential heterosis. The author think it is a means to predict heterosis using molecular markers, which can provide theory basis for parent selection in hybridization breeding.