The Improvement Of The Resistance To Rice Blast Disease In N175 By Marker-assisted Selection

As one of the most important cereal crops,rice(Oryza sativa L.)plays a key role in food production in the world.But the yield of rice is often cost huge loss by rice blast each year.It has proved that breeding new varieties with multi-resistances was the most effective and economical strategies to control this disease.A large number of blast-resistant genes have been identified Currently,among which Pi-Kh,Pi-1 and Pi-9 are wide-spectrum resistant genes.N175 is an elite restorer line for hybrids,but it is susceptible to rice blast disease.In this paper,three blast disease resistant genes,Pi-Kh,Pi-1 and Pi-9 from donor parent Jinhui1059 were introgressed into N175 by means of marker-assisted selection(MAS).The main results are as follows:1.Donor parent Jinhui1059 with the Pi-kh,Pi-1 and Pi-9 was crossed with the recipient parent N175 and followed by 3 times of backcrossing,and MAS was used to select the target genes during the breeding process.The three genes,Pi-Kh,Pi-1 and Pi-9 were successfully pyramided into N175 and 16 near-isogenic lines were bred,which were very similar with N175 in agronomic traits,but the resistance to rice blast disease of them have been greatly improved.2.The results of blast resistance test in greenhouse and field indicated that,the level of resistance of the 16 near-isogenic lines are significantly higher than that of the sensitive control,N175,and are similar with the donor parent Jinhui1059.Their hybrids derived from Longtepu A also show significantly higher resistance than that of Teyou175.Those results show that the improvement of the resi stance to rice blast in N175 is successful.3.The results show that hybrids derived from the near isogenic lines of N175 and Longtepu A are very similar in main agronomic traits compared with Teyou175.8 of the hybrids show significantly higher weight than that of the control,Teyou175 in grain weight per plant.In additionally,2 of the hybrids produce more than 10%of the yield than that of the control variety.Our results show that most of hybrids derived from the new bred near isogenic lines and Longtepu A maitain the good agronomic traits of Teyou175 and a few line is better than the original variety,Teyou175.