Identification of Molecular Markers for a Aphid Resistance Gene in Sorghum and Selective Efficiency Using These Markers

In this study, an F-2 segregated population obtained by hybridization between the aphid-sensitive sorghum strain Qiansan and aphid-resistant cultivar Henong 16 was used to establish an aphid-resistant pool and an aphid-sensitive pool. 192 pairs of AFLP (amplified fragment length polymorphism) marker primers were screened in these pools using BSA (bulked segregant analysis). Three pairs of EcoR I-CTG/Mse I-CCT, EcoR I-CTG/Mse I-CAT, and EcoR I-A GT/Mse I-CCC showed linkage with aphis resistance. EcoR I-CTG/Mse I-CCT-475, EcoR I-CTG/Mse I-CAT-390, and EcoR I-AGT/Mse I-CCC-3 50 (E42/M52-350) were mapped within 6, 10, and 13 cM distances with the aphid-resistant gene by using Mapmaker 3.0 software. The bands amplified by EcoR I-CTG/Mse I-CCT-475 and EcoR I-CTG/Mse I-CAT-390 were extracted, cloned, and sequenced. Specific primers of SCAR (sequence characterized amplified regions) were then designed from these bands. A specific band of 300 bp was amplified by a pair of SCAR primers designed based on the sequence obtained from the EcoR I-CTG/Mse I-CAT-390 marker. The SCAR marker was named SCA50. The marker was used to detect the F2, BC,, and F-2:3 populations. The selective efficiency was 86.8, 91.1, and 86.3% in the BC1, F-2, and F-2:3 populations, respectively. The average selective efficiency was 88.2%.