Development And Utility Of EST-SSR Marker And Construction Of Potato(Solanum Tuberosum L.) Germplasm Fingerprinting

Potato(Solanum tuberosum L.)is not only a food and vegetable crop,but also industrial raw material.It plays an important role in economic development and food security.It is difficult to identify potato varieties accurately by traditional botanical characters with the increasing of potato varieties.Although the potato genome sequencing has been conducted,molecular markers,especially those associated with genes,for large-scale analysis are relatively inadequate which limits the research on genetic breeding of potato.In this study,the MISA software was used to screen the potato genome for SSR loci.Then polymorphic EST-SSR markers were developed based on redundancy and polymorphism of EST sequences in Genebank.After that the EST-SSR primers were employed to analyze the genetic diversity and build fingerprints of 44 potato varieties.The main results are as follows:1.A total of 144813 SSR loci were identified across the potato genome sequence by MISA,with an average of one SSR per 4.98Kb.15546 unique SSRs were found.The chromosomal distribution of unique SSRs is similar to the total SSRs.The number of SSR loci is related to the length of chromosome,but the density of single SSR locus is more variable.2.SSR loci tend to locate in the non-coding region of potato genome.In different regions of the genome,the SSR loci densities are:Intergenic>Intron>Promoter>Exon.The number of SSR differ with repeating units,(A/T)n accounted for 70.44%and 70.43%of total MNRs SSR and unique MNRs SSR loci,respectively.As for DNRs,(AT/TA)n has the hightest rate,and only 2(CG/GC)n were indentified.(AAT)n was the most frequent TNRs motifs.3.17 of 40 pairs of SSR primers were selected based on 10 potato material,to analyze genetic diversity and build fingerprint.The 17 primer pairs amplified a total of 138 alleles among the 44 potato breeding resources.The average allele was 8.1 per SSR locus.136 alleles were proved to be polymorphic alleles,and the ratio of polymorphism was as high as 98.5%.The polymorphic information content values(PIC)ranged from 0.6607 to 0.8786,with a mean of 0.8073.4.Genetic distance estimated by NTSYSpc showed that:the average distance among 44 accessions was 0.3424,varying from 0.0296～0.5111.All the materials could be divided into five groups at genetic similarity of 0.632,and 75%of the materials were clustered into one group.It’s indicated that the genetic basis of 44 potato breeding resources was narrow.5.44 potato materials could be identified by 5 pairs of primer:SAUE151、SAUE22、SAUE015、SAUE003 and SAUE008.DNA fingerprints of 44 potato breeding resources were constructed.