Differential Expression Analysis And Functional Analysis Of Genes Related To Rice Bacterial Blight Resistance

Rice is one of the most important crops in the world, and rice is the majority’s staple food in China.Rice bacterial blight （BB） is one of the most serious diseases of rice and has serious threat to riceproduction. The most economical and effective method to control this disease is finding resistance genesand breeding resistant varieties. Researching the mechanism of interaction between rice and Xoo areconductive to the application of rice resistance gene and to the richness of gene resource of rice.Through that our people’s life can be protected and the economic development will be accelerated.Wild rice germplasm Y238has a broad-spectrum resistance to bacterial blight. Introgression linesCBB30I derived from cross and backcrosses between Y238, the BB resistance donors, and thesusceptible cultivar IR24, the recurrent parent, also has the broad-spectrum resistance. In this study,differentially expressed cDNA library between CBB30I and IR24was constructed by using suppressionsubtractive hybridization （SSH）. cDNA clones showing differential expressions were found after reverseNorthern blot analysis, sequencing and BLAST analysis. Differential expressions of the BB-resistancerelated genes in incompatible and compatible interactions were further proved by semi-quantitativeRT-PCR.After bioinformatics analysis of unknown function gene OsE₁₂, over-expression vector andRNAi vector of OsE₁₂were constructed and transformed into rice calli, and positive transgenic riceseedlings were got. Resistance function of OsE₁₂was also proved. The results obtained in this studyare as follows:1. Thirty unique cDNA clones showing differential expressions were found after PCR analysis,reverse Northern blot analysis, sequencing and BLAST analysis, and the clones code different genes.2. The genes screened were divided into six categories according to MIPS （Munich InformationCenter for Protein Sequences） functional classification system, and the differentially expressed genesare involved in some important biological processes, such as pathogen response, signal transduction,protein synthesis and protein fate etc.3. The expression of the resistance related genes in CBB30I was higher than in IR24by RT-PCRanalysis, and that proved the differentially expressed genes and the expression level was relevant to BBresistance.4. Among the key resistance related genes in CBB30I, there were four genes of inducibleexpression and two genes of constitutive expression.5. The OsE₁₂gene in CBB30I and in IR24was cloned, and the DNA sequence of this genewas sequenced through. The exon, protein sequence, signal peptide, transmembrane helix, conservedsites were predicted, and these characteristics were compared among CBB30I, IR24and Nipponbare,and the difference of these characteristics among the three rices may be the reason to cause thedifference of resistance.6. Over-expression vector and RNAi vector of OsE₁₂gene were constructed and transformedinto rice calli. 7. Positive transgenic rices transformed by excessive expression vector were got and identifiedby PCR and infection of Xoo, and the results showed OsE₁₂gene involved in the resistance processof rice bacterial blight. The rice calli transformed by RNAi vector were also got.