Molecular Marker-assisted Breeding Of Rice Restorer Lines Resistant To Rice Blast And Brown Planthopper

Rice Blast and Brown Planthopper bring huge damage to rice production every year,using resistance genes to breed new varieties with disease and insect resistance is the dominant trend in current.What’s more,introduction and aggregation of multiple disease and insect resistance genes are also considered to be the greenest methods.In this study,Molecular marker-assisted selection（MAS）,combined with conventional crossbreeding and backcross breeding methods,was used to transfer the Rice Blast resistance gene Pigm and the Brown Planthopper resistance genes Bph14 and Bph15.The improved stable lines were analyzed in terms of background recovery rate,agronomic traits,rice quality,and combining ability,and a batch of improved materials with different advantages against rice blast and brown planthopper resistance were screened out,and to provide certain reference value for the application of Pigm,Bph14,Bph15 in breeding.The main findings are as follows:1.By importing Pigm,91 copies of materials of different generations have been obtained,including 37 copies of B₁F₃,21 copies of B₂F₂,15 copies of B₃F₁,and 18copies of F₄.18 B₁F materials were planted in the Jing Gang Shan National Blast Resistance Base for field phenotype identification in June 2019.The results showed that the improved strains had significantly improved resistance compared to the recurrent parents.2 materials reached the resistance level and 11 reached the level of medium resistance,and 5 reached the level of medium sensitivity.2.Background analysis of stable materials shows:The actual recovery values of the 9311（Pigm）lines were 95.31%～96.875%,which was close to the theoretical value of 96.875%.However,the actual background recovery rates of Changhui T025^-Bph14 and R319（Bph15）lines were 85.64%～94.55%And 86.14%～95.55%.All 9311（Pigm）lines had extremely significant reductions in filled grains number and seed setting rate.What’s more,the duration from seeding to heading was shortened in Hainan while extended in Nanchang.The best comprehensive performance of the agronomic traits was A4.In terms of rice quality,all the lines showed extremely significant reductions in alkali spreading value.and Comprehensive rice quality performed the best with A1.In terms of combining ability,the general combining ability is A1,which can be used to select hybrid combinations with strong tillering ability,resistance to fall and high yield.The combination of SCA effect values of plant height and yield per plant,which performed well were:Ming S/A1,016A/9311,and Ying S/A5.All Changhui T025^-Bph14 strains significantly reduced on the secondary branches,total grains number and filled grains number,but significantly improved the seed setting rate and thousand-grain weight.The best comprehensive performance of the agronomic traits was B1.In terms of rice quality,the brown rice rate in all strains was increased,and B3 to B6 reached extremely significant levels,and Comprehensive rice quality performed best with B4.In terms of combining ability,the general combining ability is more prominent with B6,which can be used to select large spike hybrids combination.The combinations with better SCA effect values of comprehensive plant height and single plant yield are:Taixiang 1209A/B5,Taixiang 1209A/Changhui T025,and Ying S/B2.All R319（Bph15）strains in the duration from seeding to heading was shorter both in Hainan and Nanchang,and the best agronomic traits were C1.In terms of rice quality,all the improved lines significantly reduced in the Chalky rice rate and Chalkiness degree,and Comprehensive rice quality was the best with C3.In terms of combining ability,the general combining ability is more prominent with C4,which can be used to select hybrid combinations with high seed setting rate and high yield.The combinations with better SCA effect value of comprehensive plant height and single plant yield are:Qiyuan A/C1,Wufeng A/C4,Qiyuan A/C3.3.By cross-reverse the stable 9311（Pigm）strain,Changhui T025^-Bph14 and R319（Bph15）strains with molecular markers,a total of 84 copies of polygenic materials have been obtained,inclouding 26 strains aggregated with Pigm and Bph14 genes,41strains that aggregated with Pigm and Bph15 genes,and 17 strains aggregated with Bph14 and Bph15 genes.