| Peanut is a vegetable oil and protein crop, widely cultivated in the world. The research of peanut germplasm resources is the basis work for breeding program. In this study, Genetic diversity of 75 peanut landraces with different botanical types in Hebei Province were screened using simple sequence repeats(SSR) molecular markers combined with phenotypic investigation. EST-SSR markers were also exploited according to more than 90,000 peanut ESTs sequences in the Genbank. The main results were as follows:1. The coefficient of variation for nine kinds of agronomic traits, such as stem height, total number of branches, biomass per plant etc. were at range of 18.65%~271.51%, which the pod with three seeds were the max. (271.51%), followed by the number of unfilled pod (46.53%) and 100-pod-weight with theleast (18.65%). Fourteen pairs of peanut traits were significantly positive correlated, while six pairs of characters were negative correlated significantly. Analysis for the principal component of the nine kinds of traitswere also carried out according to the standard of the cumulative contribution rate of over 85.00%, Five Feature roots including 100-pod-weight, pods per plant, pod with three seeds, stem height and number of empty (unfilled) pods were selected, which the corresponding feature vector cumulative contribution reached 89.13%.2. Using 36 pairs of SSR primers, 75 landraces of peanut were screened and 125 alleles were detected,with 2 to 6 alleles per locus and average of 3.47. Shannon information index of different botanical genotypes ranged from 0.17 to 1.36, average is 0.62 for each pair of primers. Polymorphism information content (PIC) ranged from 0.50 to 0.96 with an averageof 0.81.The genetic similarity ranged from 0.193 to 0.976 with an average of 0.618, which Qianxi Liyang and Xinle Dashaiguo were the lowest, while Wangdu Huasheng and Hejian Paman werethe highest.3. Cluster analysis showed that five groups were clustered towards agronomic traits and SSR markers which showed the high consistency between the phenotypic investigation and genotypic detection. In addition, the same geographical origin of landraces were not clustered into the same groups, which indicated that the genetic relationships of the peanut landraces had little relationship with their geographical origins.4. From 92403 peanut EST sequences, we obtained 2273 non-redundant EST sequences and detected 2594 SSR sits. In 2~7bp repeated primitives, tri-nucleotide motif (65.54%) as the most abundant motif types followed by di-nucleotide (28.10%). Among the 92 repeat types the top eight motif types with high frequency included AG/TC (20.1%),AAG/TTC(11.8%),AAT/TTA (10.1%),AGG/TCC (6.6%),AGA/TCT (6.3%),AT/TA (5.9%),ACT/TGA (3.8%),ATG/TAC (3.7%). A total of 237 primer pairs were successfully designed based on the 2267 SSR-ESTs.
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