扬稻6号背景下不同稻瘟病广谱抗性基因聚合效应研究

发布时间：2018-12-06 12:26

【摘要】：由子囊菌Magnaporthe oryzae引起的稻瘟病是一种世界性的水稻病害。由于其危害面积逐年增大且危害程度日趋严重,已成为水稻高产稳产的巨大障碍。长期的生产实践表明,利用抗病基因培育抗病品种是防治稻瘟病最为经济有效的方法。然而,由于稻瘟病菌的致病性分化严重、生理小种多、变异频繁,给抗病品种的选育带来了困难,一个抗病品种往往推广种植3～5年便“丧失”抗病性。因此,一方面必须对稻瘟病菌进行深入研究,监测分析稻瘟病菌群体的小种组成及时空变化,预防稻瘟病的大范围发生;另一方面,需要鉴定优异的广谱抗性基因,并将这些广谱抗性基因导入水稻品种或通过基因聚合使品种抗性更具有广谱性和持久性。本研究收集了不同生态区的稻瘟病菌,分析了其生理小种组成、分布及侵染特性。从采自浙江、广东、安徽、广西、海南、江苏、湖北、湖南、江西、四川等10个省份的稻瘟病病样中,通过单孢分离获得158个单孢菌株。利用中国七个鉴定品种进行苗期鉴定,所采集分离的158个单孢可分为7个小种群27个生理小种,且小种分布具有明显的区域特异性。在南方籼稻种植区(广东、湖北、广西、江西、四川等),ZB小种群所占比重较大,为优势小种群;而在粳稻为主的种植区(江苏),则以ZE、ZG为优势小种群、ZE1、ZG1为优势小种;在籼/粳混栽区(浙江、海南、湖南、安徽等),除浙江只有ZB菌群之外,海南、安徽和湖南地区出现多个小种群,且以ZA、ZB、ZC和ZG小种群所占比重较大。以扬稻6号为轮回亲本构建的近等基因系(Pigm、Pi40、Pi9、、Pi2、Piz)与近等基因系Pi1、Pi33、Pi54分别进行两两杂交,通过分子标记辅助选择进行筛选,成功构建了一套双基因聚合系(18个基因组合)。同时针对每个目标基因组合选择2-4个农艺性状与扬稻6号相似的株系通过全基因组测序(GBS)进行背景回复率检测,基于测序结果分析,所选择的各双基因聚合系背景回复率都在98.02%以上,分布在98.02%(Pi9+Pi1)-98.98%(Pi2+Pi33)之间,并均保留了扬稻6号本身携带的稻瘟病抗性基因,从而使后续的抗性分析建立在一致的抗性遗传背景上。在人工接种条件下,不同双基因聚合系之间的抗性效应存在明显差异。与受体亲本相比,各双基因聚合的抗性水平均有不同程度的提高。抗性效应最好的为Pigm+Pi1、Pigm+Pi33、Pigm+Pi54、Pi9+Pi1、Pi9+Pi54、Pi2+Pi1 Pi2+Pi33,它们的苗瘟及穗瘟抗性频率都在90%以上。同时,我们发现不同基因聚合后,大部分基因组合都产生了正向聚合效应,仅有少部分基因组合产生了负向效应,如Piz+Pi33和Pi54+Pi33。此外,在自然诱发条件下,只有Pigm+Pi1、Pigm+Pi33和Pigm+Pi54在三个病圃表现最稳定,而其余基因组合抗性效应则存在地区特异性。基本农艺性状调查结果显示,除携带有Pi2的双基因聚合系表现出抽穗期提前、每穗粒数变少、单株产量降低外,其他双基因聚合系的基本农艺性状均与轮回亲本扬稻6号无明显差异。
[Abstract]:Rice blast caused by ascomycetes Magnaporthe oryzae is a worldwide rice disease. It has become a great obstacle to high and stable yield of rice because of its increasing damage area and serious damage degree year by year. The long-term production practice shows that breeding resistant varieties with disease resistance genes is the most economical and effective method to control rice blast. However, because of the serious pathogenicity differentiation of rice blast fungus, many physiological races and frequent variation, it is difficult for the breeding of resistant varieties. A disease-resistant variety often loses its disease resistance after 3 ~ 5 years of planting. Therefore, on the one hand, it is necessary to carry on the thorough research to the rice blast fungus, to monitor and analyze the small species composition and the time and space change of the population of rice blast, so as to prevent the large-scale occurrence of rice blast. On the other hand, it is necessary to identify excellent broad-spectrum resistance genes and to introduce them into rice varieties or to make them more broad-spectrum and persistent through gene aggregation. In this study, the composition, distribution and infection characteristics of rice blast fungus in different ecological regions were analyzed. 158 strains of rice blast were isolated from 10 provinces of Zhejiang, Guangdong, Anhui, Guangxi, Hainan, Jiangsu, Hubei, Hunan, Jiangxi and Sichuan. In the seedling stage identification of seven identified varieties in China, 158 single spore species collected and isolated can be divided into 27 physiological races of 7 small populations, and the distribution of racemes has obvious regional specificity. In southern indica rice growing areas (Guangdong, Hubei, Guangxi, Jiangxi, Sichuan, etc.) the proportion of), ZB small population is large, which is the dominant small population; In the japonica rice planting area (Jiangsu), ZE,ZG was the dominant small population and ZE1,ZG1 was the dominant small species. In indica / japonica mixed planting areas (Zhejiang, Hainan, Hunan, Anhui, etc.), there were many small populations in Hainan, Anhui and Hunan, except for the ZB microflora in Zhejiang, and the small populations of ZA,ZB,ZC and ZG accounted for a large proportion. The near isogenic line (Pigm,Pi40,Pi9,,Pi2,Piz) and the near isogenic line (Pi1,Pi33,Pi54) constructed with Yangdao 6 as recurrent parent were crossed by pairwise hybridization and screened by molecular marker-assisted selection. A set of double gene polymeric lines (18 gene combinations) was successfully constructed. At the same time, 2-4 agronomic traits similar to Yangdao 6 were selected for each target gene combination to detect the background response rate by whole genome sequencing (GBS), and the results were analyzed based on the sequencing results. The background response rate of the selected polymorphic lines was above 98.02%, distributed between 98.02% (Pi9 Pi1) and 98.98% (Pi2 Pi33), and the blast resistance genes of Yangdao 6 were retained. So that the subsequent resistance analysis is based on the consistent genetic background of resistance. Under artificial inoculation, there were significant differences in resistance effects among different polymorphic lines. Compared with the recipient parents, the resistance level of the two-gene polymerization was increased in varying degrees. The best resistance effect was Pigm Pi1,Pigm Pi33,Pigm Pi54,Pi9 Pi1,Pi9 Pi54,Pi2 Pi1 Pi2 Pi33,. The frequency of seedling blast and panicle blast resistance was over 90%. At the same time, we found that after different gene aggregation, most gene combinations produced positive aggregation effect, only a few gene combinations produced negative effects, such as Piz Pi33 and Pi54 Pi33.. In addition, only Pigm Pi1,Pigm Pi33 and Pigm Pi54 showed the most stable resistance in the three nurseries under natural induced conditions, while the resistance effects of the other gene combinations were region-specific. The investigation of basic agronomic characters showed that, except for the double gene polymeric lines carrying Pi2, the heading date was earlier, the number of grains per panicle decreased, and the yield per plant decreased. There was no significant difference between the basic agronomic characters of other double gene polymeric lines and the recurrent parent Yangdao 6.
【学位授予单位】：扬州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S435.111.41

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