Improvement Of Blast And Stemborer Resistance Of TianfengA, A CMS Line Of Rice(Oryza Sativa L.)

Blast caused by the fungus Magnaporthae grisea (Herbert) Borr.(anamorphe Pyricularia oryza Cav.) is one of the most serious diseases of rice over China, which cause the yield losses and fall off in quality of rice. Stemborers (yellow stemborer, tryporyza incertulas and striped stemborer) and leaffolders are two species of Lepidopteran insects that cause severe damage to rice production in China. Molecular marker-assisted selection (MAS) and transgenic technologies will be effective ways to improve the resistances to the disease and insects in rice breeding.In this study, we introgressed blast resistance genes Pil, Pi2and cry1C*into a CMS line, Tianfeng A, by using backcross and MAS methords for developing new CMS lines with resistance against blast and stemborers. The main results are as follows:1. Breeding new CMS lines resistant against blast:The blast resistance genes, Pil and Pi2, were introgressed into a maintainer line, Tianfeng B by molecular-marker assisted backcross selection methods. Two maintainer lines carrying Pil and Pi2and two maintainer lines carrying Pi-2were selected. The results of identifications showed that the four lines were moderate resistant or resistant against blast. Four new CMS lines designed as Huafeng1A (carrying Pi1and Pi2)Huafeng2A (Pi1and Pi2), Huafeng3A (Pi2) and Huafeng4A(Pi2), were developed through backcrossing four selected lines to Tianfeng A for four times. The results of dynamic pollen sterility observations showed that the pollen sterility of four new CMS lines were stable sterile completely. The heterosis identification of hybrids between four new CMS lines and five restorer lines showed that the grain yields, rice quality, growth duration and other main agronomic traits were as similar as Tianfeng A derived hybrids.2. Breeding new CMS lines resistant against stemborer and leaffolder:The Bt gene, crylC*was introgressed into the maintainer line, Tianfeng B, by backcrossing to T1c-19, by selecting bar (a gene associated marker) and functional primers in gene. Three new maintainer lines carrying crylC*were selected. The backcrossing between TianfengA and three new maintainer lines were carried out for four times. Three new CMS lines carrying cry1C*designed as Huafeng6A, Huafeng7A and Huafeng8A were developed. The results of dynamic pollen sterility observation showed that the pollen sterility of three new CMS lines were stable. The heterosis identification of hybrids between three new CMS lines and five restorer lines showed that the grain yields, rice quality, growth duration and other main agronomic traits were as similar as Tianfeng A derived hybrids. 3. Pyramiding of Pi1, Pi2and cry1C*:The plants carrying Pi1and Pi2from BC3F1generation of Tianfeng B4/Hua108B were crossed with the plants carrying cry1C*from BC3F1generation of Tianfeng B4/T1c-19. Eight maintainer lines carrying three genes were selected by pyramiding MAS. These eight new maitainer lines were backcrossed to Tianfeng A for three times. Their pollen sterility, blast and stemborer and leaffolder resistances, and combining ability will be identified in future.