Pathogenicity To Xa21-Transgenic Rice And Diversity Based On PCR Of Xanthomonas Oryzae Pv. Oryzae In China

The pathogenicity of various Xanthomonas oryzae pv. oryzae (Xoo) strains to three Xa21 -transgenic rice varieties (including maintainer line "Wan21B", sterile line "Wan21A", hybrid line "KangYou97" ) was evaluated in greenhouse and field and C1-C7 strains, the representative strains of Chinese pathogenic Xoo to the three Xa21-transgenic rice variedies at initial-tillering stage and full-tillering stage respectively;The PCR method to identify different pathogenic Xoo strains was built in this study.The pathogenicity of 20 Xoo strains to three Xa21-trangenic rice varieties, three non-transgenic rice (include maintainer line "80-4B", sterile line "80-4A", hybrid line "80You98") correspondingly and non-transgenic hybrid rice control "ShanYou63" were evaluated by clipping inoculation method in greenhouse and field. The primary results showed that the 3 Xa21 -transgenic rice varieties expressed excellent resistance to Xoo C1-C7 strains compared to non-transgenic rice varieties and although the disease resistance of Xa21 -transgenic hybrid line to C1-C7 strains litter lower man Xa21-transgenic maintainer line and sterile line, there was no significant difference between the disease resistance of three transgenic rice varieties. In addition, Xa21-gene endues the three transgenic rice varieties with good resistance to Xoo strains HF004 isolated from Anhui province, but no resistance to Xoo strains WH01-WH10 isolated from Hubei province. In this study, the non-transgenic rice "ShanYou 63" exhibits the same excellent resistance to Xoo strains C6 as Xa21-transgenic rice.The pathogenicity of C1-C7 strains to three Xa21-transgenic rice varieties which at initial-tillering stage and full-tillering stage respectively were also studied in field trial. The results revealed that three Xa21-transgenic rice varieties at full-tillering stage shows litter better resistance than the initial-tillering, but there was no significant difference.C1-C7 strains were compared by their IS-PCR fingerprint based on J3 primer, designed depending on the sequence of IS1112 which is a special insert element of Xoo, and ten typical products of IS-PCR, which belong to C2 and C5 strains were sequenced and analyzed. The results were compared with the genome sequence of Korea Xoo strain KACC10331, which published in GenBank. 2-3F/2-3R and 5-4F/5-4R, 2 pairs of primers which designed based on the sequence characteristic of 2 of the 10 products completed in this study and the genome sequence of KACC10331 strains were screened out and could be used to identify different pathogenic Xoo strains effectively. The diversity were revealed according to if the PCR products included the sequence of IS1112 by the two pairs of primers. Depended on the 2 pairs of primers, the seven Xoo strains C1-C7 were identified into 3 types, C1 and C4 belong to the first, C2, C3, C6 and C7 fall into the second, C5 remains with the third. Furthermore, the 2 pairs of primers were also used to identify the 10 and 255 Xoo strains which from Hubei province and Anhui province respectively, and all of the 265 Xoo strains were identified as the first type according to the length of PCR products in the pilot study.