| Dactylis glomerata is a famous cool season forage grass of Poaceae family around the world, which is also a core speices used for animal husbandry and construction of ecological grassland. In order to improve the lack of cultivars and narrow genetic base,23 accessions were selected, which included 6 tetraploid cultivated orchardgrass,2 tetraploid new strain lines and 6 diploid wild materials,3 tetraploid wild materials and 6 D. glomerata subsp. SSR marker were used to reveal genetic diversity among these germplasm. And hybrids among dipoid, tetraploid, diploid and tetraploid parents were done by sets of bags in term of genetic distance, flowering date and relevant agronomic performance, then true hybrid individuals were identified by SSR marker among 180 F1 progenies from 17 hybrid combinations. And genetic variation was also detected by it. The results were as followed:1) Study on genetic diversity showed that 25 SSR primer pairs were used to amplify 23 accessions (including cultivar, tetraploid, diploid and so on) in this study,251 clear bands were obtained, and the average number of bands per primer pair was 10.04. The percent of polymorphic bands was 100. The average genetic diversity, as meansured by the polymorphism information content (PIC) was 0.33, ranging from 0.24 (A01E14) to 0.42 (A01F24, A03B16). The genetic distance of 23 accessions varied from 0.1065 to 0.6061, with an average of 0.3870. Clustering analysis divided 23 accessions into different groups according to the geographic distributions, ploidy and cultivar. Principal component analysis was consistent with clustering analysis. Analysis of molecular variance indicated that the genetic variation was higher within group than among groups. The result of comparison of genetic diversity among different groups showed that there was no significant difference between the group of wild orchardgrass and the group of cultivated orchardgrass, but the genetic diversity of tetraploid group was much richer than diploid group.2) In the experiment of hybrids identification, SSR marker were amplified among tetraploid combination, diploid combination and tetraploid and diploid combination to identify turely F1 progenies,10,21,10 primer pairs were chosen, respectively. The percentage of plolymophic band between female and male parents were 93.44%,79.22%, 89.29%, respectively. And this index has positive correlation with efficiency of primer selection. All tetraploid combinations had true hybrids, the percentage of true hybrids was 75% (T3, T6) to 100%(T2), however none of the individuals in diploid and tetraploid combination DT4 and diploid combinations D5 and D6 were identified as ture hybrids. The percentage of true hybrids of these two types were 7%(DT3)-100% (DTI) and 10% (T4)-75% (T1), respectively. The result also indicated the high possibility of pollinations among different tetraploid accessions.5 types of band were observed in progenies which was amplified by SSR marker. And type b was complementary type, which had both male parental specific band and female parental band and type d called female parental type that commonly showed up in all combinations. Compared with the other two hybrid combination types, tetraploid hybrid combination had more types of bands. |
PDF Full Text Request