Breeding Restoret Lins With Resistance To Brown Planthopper In Hybrid Rice By Molecular Marker Assisted Selection

Hybrid rice has made important contributions to increase rice yield. The brown planthopper is one of the most hazardous insect pests in hybrid rice. The main solution to the problem is to spread pesticides. Another problem about environmental pollution and pesticide residues in rice is growing serious by using of chemical pesticides. That the most cost-effective method to prevent brown planthopper is breeding new hybrid rice varieties with resistance gene.We gain a new rice line, CN311, that resistant to BPH by marker-assisted selection technology combined with the traditional breeding. The parents of CN311 are 9311 and BPH Resistant Rice B5, which contained Bph14 and Bph15 gene.We obtained three new lines K39-744, K39-745 and K39-747, which contained two homozygous markers of restorer gene and two homozygous markers of resistance to brown planthopper gene. The parents of K39-744, K39-745 and K39-747 are R188, which contained Rf3 and Rf4 gene, and CN311, which contained Bph14 and Bph15' gene.The three new lines'and the parents'agronomic traits is investigated. The three new lines, K39-744, K39-745 and K39-747, were similar in appearance. We found the three lines are more closer to CN311 than R188 in agronomic traits.We constructed the three new lines'genetic physical map using SSR markers. All the three lines'chromosome segments which contained Bphl4 and Bph15 are derived from the corresponding segments of CN311. And the chromosome segments which contained Rf3 and Rf4 are derived from R188. The genetic background showed that four genes, Bphl4, Bph15, Rf3 and Rf4, are gained by the three new lines.With control which contained TN1,9311, R188 and B5, the three new lines' resistance to BPH is investigated with standard seedbox screening technique. The results show, TN1,9311 and R188 are no resistance to brown planthopper. Both B5 and CN311's resistance to BPH level are immune. The resistance of K39-744, K39-745 and K39-747 are high resistance level.Test crosses is designed and analysed between Chuangu A, female and K39-744, K39-745 and K39-747, male. We found the three new lines have good restorability and great potential to breeding hybrid rice.The restorability of Rf3 and Rf4 is studied preliminarily. The results show that the restorability which plant contained both Rf3 and Rf4 markers is bigger than only one of them. And the restorability which plant contained Rf4 gene marker is bigger than Rf3 gene mark. This may indicate that there is additive genetic effect on Rf3 and Rf4, and the Rf4's restorability is bigger than Rf3's. The results is consistent with the results from previous studies.Summary, we have obtained three restorer lines which have high resistance to BPH. This study found a probalility to breeding new varieties of hybrid rice resistance to BPH.