Improvement Of Bacterial Blight Risistence Of Rice(Oryza Sativa L.)by Molecular Marker-assisted Selecion

Abstract The Bacterial Blight (BB), caused by Xanthomonas oryzae pv. oryzae (Xoo), is one of the most serious disease of rice (O~yza sativa L.) worldwide., because of the resistance gene in rice being single ,the tendency of rice becoming susceptible to Bacterial Blight (BB) has been increasing in recent years in China扴huhui527?is a new promising restore line ,bred by Rice Research Institute of Sichuan Agricultural University in 1996,but its widely usage is limited because it is susceptible to Bacterial Blight (BB).The objective of this study is to improve the Bacterial Blight (BB) resistance of 慡huhui527抌y applicating Molecular Marker-assisted Selection (MAS) and traditional breeding technology to pyramid Xa2 land Xa4,two dominant bacterial blight (BB) resistance gene. The donor parent is IRBB6O(Xa2lIXa4IXa5IXal3) ,the receiptor parent is 慡huhui527? The marker pTA248 and MP12,tightly combined with Xa21 and Xa4,respectively ,used to marker-assistedd selection.During 3 years,the resistance gene Xa4 and Xa2 1 were pyraniided into 慡huhui527?by Molecular Marker- assisted Selection (MAS), connected with continuous backcrossing and traditional selection .The new system of Molecular Marker-assisted Selection (MAS) is also established The main results are following: I. Two methods are used to eXtract DNA of rice, large-scale method and mini-scale method ,The PCR products of DNA from the two methods demonstrate that the results of this two method are similar ,both the quality and quantity of DNA from the mm - scale method are enough for Molecular Marker-assisted Selection (MAS). 2. By the Molecular Marker-assisted Selection (MAS) and traditional breeding technology,27 plants ,containing Xa2lXa2lIXa4Xa4 and agricultural traits being similar to 慡huhui527?are gained. 3. 120 SSR primers ,distributed on the 12 chromosomes of rice ,are use to analysis the genetic background of the 22 plants (Xa2lXa2l/Xa4Xa4),selected from population (Shuhui527I/I Shuhui527// Shuhui527/IRBB6O)F1.and its agricultural 2 traits are the most similar to扴huhui527? It shows that the similar ratio of genetic background to 慡huhui527?range from 93.3% to 99.1%. 4. lii order to estimate the accuracy of MAS with pTA248 ,tightly combined with Xa21.The 96 plants selected from the population ( Shuhui527// Shuhui527/IRBB6O) F1 are inoculated race P6,.The result shows that the accuracies of pIA248 selected for Xa2lXa2l and Xa2lXa2l reach to 100% and for the Xa2lXa2l(R.r) is 96%. 5. The population having only Xa21 and The population having Xa21 and Xa4 are inoculated by P6.The results are that the average lesion length of the former is longer than that of the latter ,which shows that the pyramiding of Xa2 1 and Xa4 can enhance the rice resistance to Bacterial Blight (BB)...