Research On Authenticity Of Peach EST-SSR（gSSR） Primers And Their Transferability In Other Rosaceae Fruit Trees

EST-SSR as a new kind of molecular marker has been developed and used in many fruit trees because it has several advantages over genomic-derived SSRs, such as easy and inexpensive to develop, high transferability, besides possessing the features of the latter one. Although the molecular and genetic research of peach as a model of perennial woody fruit crops has been made more progress, little attention has been paid to the potential transferability of peach EST-SSRs to other Rosaceae relatives. In this study, 50 pairs of peach EST-SSR primers from polymorphic 298 pairs were chosen randomly, and sequencing analysis of amplification was conducted to verify the authenticity of markers. 50 pairs of peach EST-SSR and 37 pairs of selected for electronically PCR polymorphic markers were used in other rosaceae trees to study transferability of primers. Some of the EST-SSRs(or SSRs) proved transferable to other species in the Rosaceae providing additional markers for comparative mapping, development of molecular markers and discovery of homologous gene among the Rosaceae family. The main results were as follows:1. Peach EST-SSR primers authenticity. Collection of DNA fragments from 50 pairs of polymorphic EST-SSR primers in 6 peach samples amplification loci for sequencing analysis. The results showed that all amplification shared the same SSR motif with EST, indicating the existence of the same motif between the amplification and designed amplification and the availability of developed EST-SSR markers. However, the same primer motif repeat number was different between different varieties.2. Peach EST-SSR primers transferability in other rosaceae trees. Randomly selected 30 pairs of polymorphic primers were amplified successfully in 4 genera and 72 species. 25, 25, 27, 27, 23 and 29 primers were successfully amplified in apple, pear, apricot, plum, cherry and strawberry, respectively. The highest rate of amplification was obtained(96.67%) in cherry. Moreover, the results showed that the EST-SSR primers amplification in rosaceae plants was polymorphic. The rate of polymorphism in apple, pear, apricot, plum, strawberry and cherry were 76.00%, 72.00%, 85.19%, 72.00%, 65.22% and 93.10%, respectively.3. Peach genome SSR primers transferability in rosaceae trees. Electronically PCR selected 37 pairs of primers amplified successfully in 4 genera and 72 species.36, 37, 36, 33, 37 and 37 primers were successfully amplified in apple, pear, apricot, plum, cherry and strawberry, respectively. Moreover, the results showed that the genome SSR primers amplification in rosaceae plants was polymorphic. The rate of polymorphism in apple, pear, apricot, plum, strawberry and cherry were 75.86%、89.19%、89.19%、83.78%、91.89% and 94.59%,respectively.4. Clustering results from EST-SSR and genomic SSR primers on Rosaceae plants. UPGMA clustering showed that there was an obvious difference in both similarity coefficient and taxa division between peach EST-SSR and genome SSR primers clustering on apple, pear and plum while merely difference in similarity coefficient on cherry, strawberry and apricot.