【作者】 李明菊；

【导师】 段霞瑜；

【作者基本信息】 中国农业科学院 ， 植物病理学， 2013， 博士

【摘要】 小麦条锈病（Puccinia striiformis West. f. sp. tritici Eriks.）是严重威胁我国小麦安全生产的重大流行性病害，云南是条锈病的重发区，是我国条锈菌能顺利越冬越夏面积最大的省份及毒性最复杂的地区，云南具有我国小麦条锈病初菌源地的重要特征及远距离传播的充要条件，在明确云南小麦条锈菌与其它流行区的关系之前，系统认识其群体结构十分重要，这有助于揭示条锈菌起源、进化及传播。根据病菌群体毒性状况开展对应的寄主群体抗性评价及抗病基因研究，能为合理利用小麦品种及实施抗病基因布局提供依据。本研究主要取得如下结果：1．条锈病发生时间序列调查由云南小麦条锈病始发期及盛发期自西南向东北逐步推迟的规律，揭示了条锈病在云南自西南向东北传播的方向，由地麦先发病田麦后发病的规律，揭示了条锈病越冬初菌源是从高海拔向低海拔传播，但复杂的小环境有时会掩盖传播走向。2．条锈菌生理小种研究通过2008-2011年云南省小麦条锈菌生理小种的研究表明，条锈菌群体正经历从以CY32、CY33、Hy-8和Hy-6等为优势小种的极不均衡的群体结构，到优势小种频率越来越低，越来越不明显的趋于均衡的群体结构，由较为简单的群体发展为越来越复杂的群体。条锈菌群体毒性的发展，迫切要求调整鉴别寄主，进行毒性研究方法的变革。采用单基因系或近等基因系作鉴别寄主，进行毒性基因及其频率分析，取代现行的生理小种监测方法势在必行。3．条锈菌SNP引物开发在国际国内首次开发出小麦条锈菌3个看家基因即促分裂原活化蛋白激酶1基因（Mapk1）、细胞周期依赖性蛋白激酶2基因（Cdc2）和延伸因子1α基因（Ef-1α）的单核苷酸多态性（SNP）引物。基于云、贵、川、陕、甘5省149个条锈菌系SNP分析，多态性好，可用于条锈菌群体结构的SNP分析。4．条锈菌分子群体遗传结构研究采用Mapk1、Cdc2和Ef-1α的连接基因，对条锈菌2008年及2011年群体共297个菌系进行SNP分析。结果表明：条锈菌群体有丰富的单倍型，云南和陇南群体有高频率的共享单倍型，分别有多个自有的单倍型。云南群体内有较大的遗传分化和较低的基因流、较高的遗传变异率。陇南群体有较高的遗传多样性及重组事件。两年的结果一致支持祖先单倍型来源于云南，云南有比陇南更古老、更年轻的基因型，更久远的进化历史，更高的异质性和进化效率。且云南、陇南两地间存在高强度的基因流等分子遗传学证据，结合寄主与病菌的协同进化及云南各地条锈病盛发期高空气流轨迹等分析，从多角度取得了云南小麦条锈菌直接传播到陇南的证据。5．小麦品种抗条锈性评价及抗条锈基因推导采用近年来优势小种CY31、CY32、CY33及多小种混合菌系系统评价了云南125个小麦品种或材料的成株期抗条锈性。结果表明：66.4%的品种对条锈病表现不同程度的抗性，从免疫到中抗，32%的品种表现良好的慢锈性，高感品种只占1.6%。采用25个国内外条锈菌鉴别菌系，对52个云南小麦生产品种进行基因推导的结果表明：云南小麦品种抗条锈基因并不丰富，只推导出10个可能的抗条锈基因。而且分布也不均衡，只有Yr9出现频率较高，为25%；Yr2+YrA、Yr6、Yr7、Yr8、Yr17、Yr21、Yr26和Yr27，出现频率均低；22个品种无法推导出抗病基因。更多还原

【Abstract】 Wheat stripe (yellow) rust is one of the most important epidemics which threaten wheat securityseverely. Yunnan is a district where stripe rust breaks out constantly. It is a province where there islargest over-summering and over-wintering areas for Puccinia striiformis f. sp. tritici (Pst), and is one ofthe rare regions where the pathogen is very complex in China. Yunnan has the important characteristicsof the origin of Pst in China and the sufficient and prerequisite conditions for long distance dispersal ofthe pathogen. It’s very important to know the population genetic structure of Pst in Yunnan beforeanswering the relationship of pathogen between Yunnan and other epidemic regions, because it canreveal the origin, evolution and migration of pathogen. Study on the host population resistance andresistance genes based on the results of pathogen virulence monitoring can provide information forrational utilization of varieties and resistance genes deployment in the field. This study obtained themain results as follows:1. Survey on the time course of the stripe rust occurrence and epidemic The step by stepoccurrence, generally directed from southwest to northeast for the beginning and the peak periods of thestripe rust, revealed the direction of dispersal for wheat stripe rust is from southwest to northeast inYunnan Province. The sequential occurrence from fields rotated with dryland farming to fields rotatedwith paddy rice revealed that the primary source of the pathogen was from high altitude areas for thepathogen overwintering. The complicated subenvironment may hide the direction of the dispersal.2. Monitoring of Pst physiological races The monitoring results of Pst during the period of2008–2011years indicated that Pst population was undergoing changes from the population structure withprevailing races, such as CY32, CY33, Hy-8, Hy-6, etc., to a more balanced structure, in whichfrequencies of dominant races lowered year after year and the population became more and morecomplicated in terms of races. The development of Pst virulence in the populations calls for theadjustment of the differential hosts and the reform of the virulence analysis method. It is urgent to use aset of single gene lines or near-isogenic lines (NILs) as differentials to analyse the virulence genes andtheir frequencies of the pathogen to replace physiological races identification method.3. Development of Pst SNP primers SNP primers had been developed of Pst house-keeping genesMapk1, Cdc2and Ef-1α for the first time in the world. The primers have good polymorphism based on149isolates from5provinces. It can be used to analyses Pst population structure.4. Molecular population genetic structure of Pst Concatenated genes Mapk1, Cdc2and Ef-1α wereused to analyse the SNP of Pst populations with297isolates altogether collected in2008and2011. Theresults indicated that Pst population had rich haplotypes. Yunnan and South Gansu population had highfrequencies of shared haplotypes. The two populations had several private haplotypes, respectively.There is great genetic differentiation, lower gene flow and higher population mutation rate withinYunnan population. There was higher genetic diversity and higher recombination events in South Gansu.The ancestral haplotype was discovered in Yunnan population from the results of both years. Yunnan has more ancient and younger haplotypes, longer evolution time, higher heterogenicity and evolutionefficiency than South Gansu. Inaddition, strong gene flow existed between Yunnan and South Gansu.Besides the molecular evidence, we also analyzed the relationship of coevolution between the pathogenand its host wheat, and the migration trajectory of Pst in upper airflow during the peak period of the rustpathogen. These provide us the evidences that Pst pathogen of Yunnan can migrate to South Gansudirectly from different perspectives.5. Resistance assessment of wheat cultivars and gene postulation Adult resistance of125wheatcultivars were assessed by inoculating the main dominant races CY31, CY32, CY33and mixture ofmany races in recent years, respectively. The results indicated that there were66.4%cultivars showeddifferent degrees of resistance from immune to mid-resistance and32%cultivars showed slow-rusting.Only1.6%cultivars showed high-susceptibility. Seedlings of52commercial wheat cultivars fromYunnan were inoculated with25differential isolates of Pst from foreign and home to postulateresistance genes to yellow rust. The results indicated that resistance gene is not rich in cultivars fromYunnan. Only10probable resistance genes were characterized in these cultivars. Yr9among them hadhigh virulence frequency,25%. Genes/combinations Yr2+YrA, Yr6, Yr7, Yr8, Yr17, Yr21, Yr26andYr27, had lower frequency. Twenty-two cultivars could not been characterized in this study.更多还原