[Pyramiding and marker-assisted selection for powdery mildew resistance genes in common wheat]

This project used the strategy of discarding susceptible individual plants and keeping resistance ones by resistance identification in breeding populations and planted resistant plants next in earlier generations (F1-F3), and performing marker-assisted selection combining resistance identification in later generation (F4 generation) for pyramiding powdery mildew resistance. F4 populations from crosses of elite parents possessing different Pm genes were screened by using molecular markers tightly linked to Pm2, Pm4a, Pm8 and Pm21 genes, respectively. Fourteen individual plants with Pm4a and Pm21 out of 40 F4 plants were identified. Sixteen individual plants containing Pm2 and Pm4a out of 80 F4 plants and six plants possessing Pm8 + Pm21 out of 58 F2 plants were screened. Notably, the plants with Pm2 and Pm4a showed high level resistance or immunity to powdery mildew, while plants with single Pm2 or Pm4a had lower resistance. The results suggest that the strategy of pyramiding different Pm genes provide an alternative way of utilizing resistance gene resources for breeding new types of resistance lines and cultivars, which will have significance not only in breeding practice but also in theoretical research.