SSR Analysis Anddevelopment Of Microsatellites In Arachis Hypogaea L.

(一) Genetic diversity and molecular classification of germplasm in genus ArachisA selection of 96 groundnut genotypes, were analysed by using SSR. Results showed that SSR molecular has abundant informativeness in the four botanical varieties of A.hypogaea L. Var.fastigiata had the most abundant infomativeness, and the second one was var.hypogaea, the next one was var.vulgaris, and the last one was var.hirsuta. The botanical var.hirsuta was the primordial cultivated peanut and var.vulgaris was the most advanced cultivated peanut.(二) SSR analysis of hybrid progenies between cultivar HeYue I and wild species A.correntinaThree cultivated peanut varieties and 19 lines obtained through hybridization of cultivar HeYuel with wild species A.correntina were screened for DNA polymorphism and transgression identification by using SSR markers. The 40 SSR primers screened, 16 of them amplified polymorphic bands, three of them (PM36, PM50, PM305) were found to be specific to the wild species A.correntina and the specific bands could be detected in several progenies. The genetic material of wild parent was integrated to these new germplasm. And PM36, PM50, PM305 could be regarded as specific genetic marker for A.correntina. SSR analysis with two primers (PM36, PM106) showed that DNA fragment pattern were not simply represented, instead there were new bands and several parental bands were absent in the interspecific derivatives.(三)Microsatellite enrichment from AFLP fragments by magnetic beadsMicrosatellites were enriched by hybridizing biotin-labeled SSR probes with AFLP fragments and captured the hybridized SSR-containing fragments by magnetic beads coated with streptavidin. After washing to remove the non-SSR fragments, the eluted single-stranded DNAs were largely enriched for microsatellites.In the method, microsatellites were enriched from pre-amplified (single-selective base primer pairs) AFLP fragments with 5 SSR probes [(GA)15, (GT),5, (AT)15, (GGC)15, (ATT)15]. The AFLP primers are EcoR-N/Mse-N. After enrichment, the eluted DNAs were cloned into plasmid and recovered by PCR using corresponding pre-amplified primers. A total of 24 positive cloned fragments were sequenced and six sequences were found to contain microsatellites when the redundant clones were excluded. The result was not ideal and a few modifications are needed for the mothod.