Improvement Of Rice Blast And Bacterial Blight Resistance Of Rice PTGMS Line GZ63-4S By Molecular Marker Selection And Genome-wide Background Selection

Rice is one of the main food crops in our country.Two-line hybrid rice is one of the important ways in utilization of rice heterosis.At present,blast and bacterial leaf blight are the major obstacles which lead to the reduction of rice yield;simplified spraying pesticide will be harmful to the environment,as well as decrease rice quality.Therefore,breeding developed two-line hybrid rices which are resistant to blast and bacterial leaf blight will be conducive to increase production and protect the environment.GZ63-4S is one of the excellent sterile lines in two-line hybrid rice breeding.The following were the main contents of this study:(1)We chosed Hua1015 S which has been breeded by our lab as the donor material,GZ63-4S as the receptor material,through hybridization and marker-assisted selection to breed new rice sterile lines resistant to blast and bacterial leaf blight.(2)Hua1015S was chosed as the donor material,GZ63-4S as the receptor material,through continuous self-cross and back-cross as well as combined with marker-assisted foreground selection and background selection,single gene(Xa23)fragments introgression line and double genes(Pi2,Xa23)fragments introgression line with the genetic background of GZ63-4S' were established.(3)Hua1201S was chosed as the donor material,GZ63-4S as the receptor material,through continuous self-cross and back-cross as well as combined with marker-assisted foreground selection and background selection,single gene(Pi2)fragments introgression line with the genetic background of GZ63-4S' were established.The main research results are as follows:1.Three new sterile lines carrying Pi2 and Xa23 were choosen from the filial generation of ‘GZ63-4S/Hua1015S' which were respectively named Hua3222 S,Hua4821S and Hua5111 S.2.The result of resistance identification showed that the resistances to rice blast and bacterial leaf blight of Hua3222 S,Hua4821S and Hua5111 S have the same resistance level with the donor parent Hua1015 S.The growth period and main agronomic traits of the three new sterile lines are between their two parents,while the plant height were all decreased obviously compared with Hua1015 S.The quality of rice is similar to GZ63-4S,but yield combining ability is inferior to GZ63-4S.Hua5111 S has the better comprehensive character,which is supposed to be used in the later breeding programmes.3.Three plants with Pi2 single gene introgression fragment(about 1.22Mb)numbered as SL16024-27,SL16024-95,and SL16024-115 were created,and the recurrent parent genome recovery rate attained 99.68%.Preliminary observation showed the three single gene introgression fragment lines have similar phenotypes to GZ63-4S,and the resistance to rice blast was obviously increased.Single gene(Xa23)introgression fragment line(about 4.77Mb)numbered as SL16025-15 was created,and the recurrent parent genome recovery rate attained 98.72%.Preliminary phenotype analysis showed that there were certain differences between SL16025-15 and GZ63-4S,and the resistance to bacterial leaf blight was obviously increased.Double genes(Pi2,Xa23)fragments introgression line numbered as SL16026-111 was created,who still preserved 0.80 Mb insert segment nearby the Pi2 gene on chromosome 6,3.34 Mb insert segment nearby the Xa23 gene on chromosome 11,10.88 Mb insert segment on chromosome 10,and the recurrent parent genome recovery rate attained 95.96%.Preliminary phenotype analysis showed that there were certain differences between SL16026-111 and GZ63-4S,and the resistance to rice blast and bacterial leaf blight were obviously increased.All the plants we obtained need to be identifed the traits and polymerized genes in the further.