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[Objective] The present paper aimed to clarify the distribution of rice blast resistance genes Pib, Pi9, Pi2, Pi54 and Pish in Japonica rice varieties (lines) and the resistance levels of different genotype to rice blast. [Method] A total of 93 rice materials were assessed by artificial inoculation and screening of molecular markers tightly linked to 5 major resistance genes. [Result] Three, two and one resistance genes were found in 19 (20. 4%), 25 (26. 9%) and 28 (30. 1%) materials, respectively, and five resistance genes corresponding to markers were found in all varieties (lines). There were 49 (52. 7%), 16 (17. 2%), 8 (8. 6%), 31 (33. 3%) and 31 varieties (lines) (33. 3%) containing rice blast resistance gene Pib, Pi9, Pi2, Pi54 and Pish in 93 varieties (lines), and the genetic frequency of Pib was the highest within this collection. A total of six genotypes and gene combinations (Pi9, Pi54, Pib + Pi9, Pib + Pi2, Pib + Pish and Pi9 + Pi54) are applicable in the rice-breeding, due to the resistance to rice blast but with low distribution in the tested varieties (lines). [Conclution] The study provided a scientific basis for breeding rice cultivars with rice blast-resistance. [ABSTRACT FROM AUTHOR]

【Objective】The present paper aimedto analyze the change of resistance of different resistance genes and gene combinations to panicle neck pest. 【Method】The genotype of 80 resource materials screened for annual resistance were detected with the functional or closely linked markers of rice blast resistance genes Pi-ta, Pi-b, Pigm and Pi54 in rice, combined with the identification of rice panicle blast resistance for two consecutive years. 【Result】The results showed that among 80 experimental materials, 4 cultivars only carried Pi-b, 5 cultivars only carried Pi54, 8 cultivars carried Pi-b+Pi54, and 10 cultivars carried Pi-b+Pi54+Pigm. Rice cultivars carrying Pi-b+Pi54+Pigm gene combination did not show high susceptibility in two continuous years’ artificial identification. Two years’ correlation analysis between resistant genes and neck blast resistance showed that the disease resistance of single gene was gradually weakened and even lost. 【Conclusion】It was an effective way to enhance the disease resistance of rice to polymerized genes with broad antimicrobial spectrum and strong resistance in rice breeding. [ABSTRACT FROM AUTHOR]

In this paper, the genetic diversity analyses of 23 varieties were conducted by 35 SSR primers. The result showed that 342 DNA fingerprints were obtained from 23 varieties by 35 SSR primers, of which 288 polymorphic DNA fingerprints occupied 84. 21 % of all. There were significantly resistant differences among 23 varieties with 8. 20 % - 75. 93 % for the DPR and 2. 19 - 52. 67 for the DI. Genetic similarity analysis based on SSR molecular marker showed that the genetic similarity of paired varieties ranged from 0. 614 to 0. 954, and mean was 0. 740, while that of single varieties was from 0. 686 to 0. 778. The means of genetic similarity of 11 varieties were lower than that of the total (0. 740 ), while the means of 12 varieties were higher than 0. 740. The 23 rice varieties were clustered into 5 genetic groups at 0. 75 similar coefficient. The varieties with different growth periods (the most differences reaching 11 days) were clustered into the same group, while the varieties with the same growth period were existed in different groups. [ABSTRACT FROM AUTHOR]