Molecular Marker-assisted Selection Of Rice Recovery Lines Resistant To Rice Blast And Brown Planthopper

Among rice pests and diseases,rice blast and brown planthopper are one of the main pests and diseases that harm rice.It is one of the important measures to control pests and diseases by using disease and insect resistance genes to select new reverted lines of disease-resistant rice and then match them to form hybrid combinations with better pest resistance.Molecular marker-assisted selection（MAS）technology is one of the most efficient methods to introduce and polymerize rice materials with multiple insect resistance genes at the same time.In this study,the gene Pigm with high resistance to rice blast and the anti-brown planthopper genes Bph14 and Bph15 were transferred to the new recovery line by molecular marker-assisted selection technology,in order to screen out improved materials with rice blast resistance and brown planthopper resistance genes and provide materials for the further development of molecular marker-assisted selection breeding of rice resistance to diseases and insects.The main findings are as follows:1.Through molecular marker-assisted breeding,Pigm was introduced into the three recovery lines of Changhui T025,Changhui 881 and R396.One homozygous strain each of Changhui 881（Pigm）,Changhui T025（Pigm）,R396（Pigm）BC₃F₄generation was obtained.At the same time,58 materials of different generations have been obtained.10 BC₃F₃ materials were planted in Jinggangshan National Rice Blast Resistance Base for field phenotype identification.The results showed that the improved lines had significantly improved resistance to leaf blast and ear blast compared with the recurrent parent,except for 1 material that reached the level of medium resistance,the other 9 materials all reached the level of medium resistance.The analysis of genetic background recovery rate showed that the actual recovery values of Changhui 881（Pigm）strain and R396（Pigm）strain were higher than the theoretical values,93.98%and 94.76%,respectively,and the actual recovery value of Changhui T025（Pigm）strain was 88.46%.2.Through the hybridization between the improved lines with a single resistance gene selected by the predecessors,the three genes of Pigm,Bph14 and Bph15 were screened and polymerized by combining the corresponding molecular markers,and four double-gene homozygous lines were obtained in the BC₃F₃ generation:Changhui T025（Bph14,Bph15）,Ganhui 3（Bph15,Pigm）,9311（Bph15,Pigm）,9311（Bph14,Pigm）.The results of seedling brown planthopper resistance identification experiments in four improved strains were performed that 9311（Bph14,Pigm）was insect resistant（R）,Changhui T025（Bph14,Bph15）,Ganhui 3（Bph15,Pigm）and 9311（Bph15,Pigm）were highly resistant（HR）to brown planthopper.In terms of combining ability,9311（Bph14,Pigm）performed the best in general combining ability,which could be used to select hybrid combinations with good tillering ability,high seed setting rate and high yield.Combinations with better SCA effect values for comprehensive plant height and yield per plant including Jingtai A/Changhui T025（Bph14,Bph15）,Changtian A/9311（Bph14,Pigm）,2551A/Ganhui3（Bph15,Pigm）.Background analysis of the homozygous material showed that the actual recovery values of Ganhui 3（Bph15,Pigm）and Changhui T025（Bph14,Bph15）were 93.88%,88.73%,and 9311（Bph15,Pigm）and 9311（Bph14,Pigm）strains were 91.58%and92.78%,respectively,which were lower than the theoretical values of 93.75%.