| Peanut or groundnut (Arachis hypogaea L.) has been an important oilseed and cash crop worldwide, with China being the largest country in terms of peanut production, consumption and export trade. The peanut market demand is expected to increase in the future because this crop possesses various advantages compared with most other oilseed crops. However, the prevalence of some important diseases have been important constraints for peanut production in China, among which, peanut stunt virus (PSV) is a crucial one particular in the north peanut producing regions. Application of resistant cultivars has been regarded as the most cost-effective way to control the viral disease. Previous studies showed that germplasm materials immune or highly resistant to PSV had been found only in some wild Arachis species while no resistant genotype was identified in the cultivated peanut. As the PSV resistance has been transferred from diploid wild species into the cultivated peanut, investigating the genetic characteristics of the resistance and identifying molecular markers linked with the resistance would be of important value for genetic improvement. In this study, an interspecific hybrid derivative, ICGV86699, with PSV resistance was used to construct recombinant inbred line (RIL). Resistance evaluation was conducted in the RILs through PSV inoculation, disease scoring and enzyme-linked immuno sorbent assay (ELISA). The genetic characteristics of PSV resistance were analyzed and SSR marker linked with PSV resistance was identified. The major findings are as follows:(1)A total of 99 pairs of EST-SSR primer were designed based on analysis of more than 60,000 ESTs constructed and sequenced in peanut. PCR amplification conditions of these primers were optimized. Among the 99 pairs EST-SSR primers, 91 pairs could amplify PCR products in six cultivated peanut genotypes, of which, 12 pairs of primers could amplify polymorphic bands.The result has contributed to increased polymorphic SSR primers which could be used in peanut research.(2)A RIL population was constructed by crossing between ICGV86699 which was a genotype derived from interspecific hybrid with resistance to PSV and Yuanza 9102 which was susceptible to PSV. Disease symptom observation, ELISA test and genetic analysis of the resistance were conducted after artificial inoculation to the RIL population (in F6 generation) containing 94 lines in isolation chamber. The results showed that the PSV resistance varied among the RIL lines. The PSV resistance showed to be controlled by two pairs genes with additive effect. The results indicated that PSV resistance originated from the diploid Arachis species could be easily transferred between peanut cultivars.(3)The two peanut parents of the RIL population were amplified by PCR using 353 pairs SSR primers, of which 56 primers could detect polymorphism between the two parents, with the polymorphic primers accounting for 15.8%. The DNAs of the RIL population (94 lines) were amplified using the polymorphic primers identified. Based on the results of ELISA test and DNA profiling by SSR, a SSR marker (XY38) linked with the PSV resistance was identified with the distance between the marker and the resistance genes being 7.5cM. The SSR marker identified might be further used for marker-assissted selection (MAS) in peanut breeding for PSV resistance. |
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