Differential Expression Of Resistance-related Genes To Xcc (Xanthomonas Campestris Pv. Campestris) In Different Radish (Raphanus Sativus L.) Germplasm

Black rot is a bacteria disease seriously influenced the production of cruciferous vegetable worldwide. In order to screen out the resistant radish germplasm and excellent disease resistance gene, three different methods were used to identify a set of radish germplasm, and DDRT-PCR and cDNA-AFLP were used to analyze the differentially expressed ESTs of five accessions of radish. The main results were as follows:1. Forty radish germplasm were inoculated with strain Xcc8004 and XccBJ of Xanthomonas campestris pv. campestris (Xcc) at seedling stage, respectively, and the fleshy root of eight germplasm among them were sliced and inoculated with strain Xcc8004. Twenty-seven accessions of them were inoculated with eight Agrobacterium with different effectors. The result indicated that radish germplasm resistant to black rot was significantly different. Three highly resistant accessions of radish germplasm to Xcc8004 were selected; one highly resistant accession of radish germplasm to XccBJ was selected. The resistance of radish seedlings to Xcc8004 was significantly correlated to the resistance to XccBJ; radish resistance of seedlings and fleshy roots to Xcc8004 was also significantly correlated. Access to reliable resources provides the basic materials for the radish resistance breeding and resistance mechanism in-depth study. Seventeen radish germplasm exhibited hypersensitive response (HR) to different effectors. HR extent of different germplasm to different effectors was different.2. cDNA-AFLP was employed to study the resistance mechanism of different radish germplasm to Xcc8004. Four resistant accessions of radish germplasm KB09-1, KB09-12, KB09-17, KB09-16 and one susceptible accession KB09-29 were used. 790 differentially expressed ESTs were obtained by 256 primers in all materials. 74 fragments were sequenced, and were divided into 8 categories according to their function. Genes related to signal transduction, protein metabolism, photosynthesis, defensive response and transport were differentially expressed in different accessions of radish germplasm. Gene differential expression of five accessions of radish germplasm against black rot disease was not identical.3. Highly resistant accession of radish germplasm ?KB09-12? was inoculated with effectors xopXccN and xopXccX2, respectively, and 153 differentially expressed ESTs were obtained by cDNA-AFLP. Twenty-five fragments were sequenced. Common ESTs from the inoculation of two effectors were mostly involved in signal transduction and defensive responses. Specific ESTs in radish inoculated with xopXccN were mostly involved in photosynthesis, while specific ESTs in radish inoculated with xopXccX2 were mostly involved in protein synthesis and processing. In comparison with differentially expressed ESTs in KB09-12 inoculated with effectors and Xcc8004, a few ESTs appeared in both hypersensitive response and disease resistance response.