| Blast disease is one of the most devastating diseases in rice production caused by Magnaporthe oryzae. It can threatened the food security of China,and cuasing serious losses of economic.Practically, the most economical and safest and environment-friendly and effective method to prevent blast disease is searching and utiliting blast-resistant varieties. Whereas, identifying excellent desirable resistant rice resources and mapping resistance gene are the prerequisite and basis of improving resistance of rice cultivars.Mutant of Taihang-68 T2 is a broad-specrum blast resistance rice variety which obtained after Space-mutation and screen. Panicle blast resistance at maturity and resistance spectrum at seedling was performed many times in Guangdong province. The results showed that T2 is resistant to most races of Magnaporthe oryzea from Guangdong province. To utilizate efficiently the blast resistance genes from T2, This study analyzed the resistance of T2, we have mapped the resistance gene in T2 by F2 populations, the markers which are tightly to blast resistance gene of T2 were searched in order to molecular marker selection and blast resistance cloning. The follows are the results of this study:l.Six core permplasms (Jingxian-89, YueXiangzhan, QingLiuai, ZhongerRuanzhan, Texianzhan-13 and PeizaTaifeng), Taihang-68 and T2 which the mutant of Taihang-68 were inoculated with 36 representative M.oryzae isolates derived from Guangdong province to identified the resistance spectrum at seedling. The results showed that T2 harbored very broad resistance spectrum, which is 80.6% and significantly, its on-groung control, Taihang-68, Jingxian-89, YueXiangzhan, QingLiuai, ZhongerRuanzhan, Texianzhan-13 and PeizaTaifeng’s resistance spectrum were 36.1%,80.6%,63.9%,72.2%,63.9%,61.1% and 69.4%, respectively. The resistance spectrum of T2 broader that that of its on-groung control, Taihang-6844.5%.Meanwhile, T2 and Taihang-68 were planted in a natural nursery, Lvtian, Conghua, and it was found that T2 performed moderately resistance and highly resistance to blast diseases in the first cropping seasons of 2012 and the second cropping seasons of 2013, respectively, it conferred moderately susceptible to neck blast in the remaining cropping seasons, Whereas, Taihang-68 conferred highly susceptible to neck blast in four cropping seasons consecutively. The results above indicated that T2 is a new broad-spectrum blast-resistance germplasm.2. The two parents, T2 and LijiangXintuanHeigu (LTH), and their F2 population were inoculated with the isolate GD0193 of M.oryzea to analyze the resistance inheritance of T2. The results show that the ratio of blast resistance to blast susceptible from F2 population was 2.95, which match to the theory ratio 3:1(χ2= o.77). The results demonstrated that a single dominant gene control the blast resistance of T23. The polymorphism analysis were peiformed between parents and pools (resistance and susceptible) with 630 pairs of SSR markers evenly distributed in 12 chromosomes of rice (Oryza sativa). The results showed that there were two SSR marker RM224 and RM27360 located on the region which is close to the telomere in the long arm of chromosome 11 showing the polymorphism between parents and pools(resistance and susceptible). Gene mapping experiment was performed further in this study, The result demonstrated that the two markers which SSR marker T5 and Intel marker K10 are closely linked with the resistance gene of T2, the genetic distances were 1.63 cM and 0.29 cM. Respectively, with cosegregating marker K7. |
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