Improvement Of The Bacterial Blight Resistance And Insect-Resistance Of Rice Restorer Line Xianhui207

Rice bacterial blight (BB) is one of the most destructive diseases in rice production in China. It can threaten the rice production, yield stability and quality in epidemic years. Stemborers and leaffolders are two groups of Lepidopteran insects that cause severe damage to rice production. The economic losses caused by these insects could account for 16 billions of yuan in China. The incorporation of resistance genes into cultivars by transgenic method and Molecular marker-assisted selection (MAS) is the most economic and effective method to control diseases and insects. Xianhui207 is an elite indica restorer line of hybrid rice, but it is highly susceptible to BB and lepidopteran insects.The objective of this study was to improve the BB resistance and lepidopteran insects resistance of Xianhui207 by MAS and backcrossing methods. Two BB resistant genes, Xa7 and Xa21, and one lepidopteran insects resistance cry1C* were used as target genes. Main research results are as follows:1. The BB resistance genes Xa7, Xa21 and the insect resistance gene cry1C* were introgressed into Xinhui207 through MAS and backcrossing methods. Through selection we obtained near-isogenic lines (NIL) containing single resistance gene Xa7, Xa21, cry1C* or double resistance genes (Xa7, Xa21) whose agronomic traits were similar to original Xianhui207's.2. Thirteen Xoo strains (PXO61, PXO99, ZHE173, GD1358, YN1, YN7, YN11, YN18, YN24, FuJ, ScYc6, HeNll and GD414), were used for identifying BB resistance of Xianhui207 and six NIL carrying Xa21 and Xa7 gene and donor parents under the field condition. The results showed that the new lines carrying Xa21 or Xa7 showed significantly higher resistance to BB than original Xianhui207. And the BB resistance of new lines carrying double resistance genes (Xa7+Xa21) were improved more. So Xa21 and Xa7 displayed high broad-spectrum resistance to Xoo races.3. Original Xianhui207, six new lines carrying Xa21 and Xa7 genes and a CMS line, Chuannongl A, were crossed. Thirteen Xoo strains were also used for identifying the BB resistance of seven F1 hybrids. The result showed that the BB resistance of new six F1 hybrids were improved significantly. So it is effective to improve the BB resistance of hybrid rice by improving the BB resistance of restorer lines.4. Two new lines carrying cry1C* gene and a CMS line, Chuannong1A were crossed. Under the field condition without pesticide-applying, the new lines and their F1 hybrids showed high insect-resistance.5. The results of combining ability analysis and grain quality analysis showed that the main agronomic traits and the grain quality of improved lines were similar to original Xianhui207's. Among the 10 agronomic traits of eight new lines, TMQ91431 had the high general combining ability (GCA) effect and specific combining ability (SCA) effect. TMQ91436 had the high GCA. TMQ91435 and TMQ91438 had the high SCA. Among the 54 F1 hybrids, the grain yield of most F1 hybrids were higher than Jinyou207 (CK). Zhong9A/TMQ91432 had the highest SCA effect in 1000-grain weight, and Jin23A/TMQ91434 had the best SCA effect in grain yield.6. The competitive heterosis of yied in 48 F1 hybrids showed that the highest competitive yield heterosis values of C815S/TMQ91431, Zhong9A/TMQ91431 and Chuannong1A/TMQ91431 over CK hybrid Jinyou207, were 20%,18.03% and 17.30%, respectively. These three combinations were resistant to Lepidopteran insects.