陇南越夏区自生麦苗条形柄锈菌毒性表型及分子基因型分析

为了解陇南地区越夏自生麦苗上条形柄锈菌的毒性组成及群体遗传结构,将采自天水、陇南及定西的自生麦苗上的39个单孢子堆菌系采用中、美鉴别寄主毒性分析法和TP-M13-SSR荧光标记技术,进行毒性鉴定并对其基因组DNA进行SSR标记分析。结果显示：在中国鉴别寄主上供试菌系被区分为9个致病类型,在美国鉴别寄主上则得到24个毒性类型,在中美鉴别寄主上共得到30个毒性表型。通过中国鉴别寄主鉴定的CYR32、CYR33为优势小种,毒性比率分别达到35.9%和30.8%。SSR标记将这些菌系划分为36个基因型,毒性分析与     

小麦条锈菌条中31号生理小种SCAR检测标记的建立

建立小麦条锈菌Pucciniastriiformisf.sp.tritici生理小种的快速分子检测技术对我国小麦条锈病的监测和防治策略的制定具有重要价值,本文首次报道了利用SCAR—PCR技术进行条锈菌生理小种分子检测的方法。通过对我国目前主要优势小种条中31号RAPD片段的规模筛选,在对特异片段回收、克隆、测序的基础上,设计特异PCR引物,成功获得了条中31号生理小种专化的SCAR检测标记。     

两系杂交小麦恢复系MR168抗条锈病基因遗传分析及分子标记定位

小麦条锈病是影响杂交小麦普及推广的重要因素。文章利用基因推导法和SSR分子标记技术,研究了温光型两系杂交小麦恢复系MR168的抗条锈性遗传规律及其控制基因染色体位置。结果表明,MR168对CY29、CY31、CY32、CY33等条锈菌生理小种表现高抗至免疫;对SY95-71/MR168杂交组合的正反交F1、BC1、F2和F3群体分单株接种鉴定显示,MR168对CY32号小种的抗性受1对显性核基因控制,该抗病基因来源于春小麦品种辽春10号。利用集群分离分析法(Bulked segregant analysis,BSA)和简单重复序列(Simple sequence repeat,SSR)分子标记分析抗病亲本MR168、感病亲本SY95-71及183个F2代单株,发现了与MR168抗条锈病基因连锁的5个微卫星标记Xgwm273、Xgwm18、Xbarc187、Xwmc269、Xwmc406,并将该基因初步定位在1BS着丝粒附近,暂命名为YrMR168;构建了包含YrMR168的SSR标记遗传图谱,距离YrMR168最近的两个微卫星位点是Xgwm18和Xbarc187,遗传距离分别为1.9 cM和2.4 cM,这两个微卫星标记可用于杂交小麦抗条锈病分子标记辅助育种。     

陇南地区不同海拔区域内小麦条锈菌群体遗传多样性的分析

小麦条锈病是世界范围内小麦上最重要的流行性病害之一,可造成严重的产量损失。陇南地区是我国小麦条锈菌主要越夏易变区和新小种发源地,了解该地区不同海拔高度区域内条锈菌遗传多样性有重要意义。本研究采用TP-M13-SSR荧光标记技术对11个种群330个小麦条锈菌分离株基因组DNA进行了SSR标记分析。不同海拔区域的条锈菌遗传多样性有明显的差异,高山区的遗传多样性比较丰富,半山区次之,川道区相对比较低。不同生态区域内,小麦条锈菌群体遗传分化程度不同,高山区和半山区遗传分化程度大,基因流小,川道区群体遗传分化程度比较小,基因流大。来自不同海拔区域的菌系具有相同的基因型,这一结果从分子水平证明了在陇南地区小麦条锈菌在山区与川地之间存在广泛的菌源交流,可就地完成周年循环。     

温室条件下条形柄锈菌体细胞重组的分子确证

为了获得温室条件下条形柄锈菌发生体细胞重组而导致毒性变异的直接证据,本研究选取7个美国条形柄锈菌小麦专化型菌系和2个美国条形柄锈菌大麦专化型菌系按照夏孢子颜色和专化型与毒性差异组成9对菌系组合,对于室内混合接种产生的子代菌系用具有不同抗性的小麦或大麦品种进行筛选,采用毒性分析及SSR分子标记技术对条形柄锈菌体细胞重组现象进行了研究。对获取的413个单孢子代菌系进行的毒性分析结果显示,有84个单孢子代菌系的毒性谱表现与亲本菌系不同,初步证明体细胞重组过程的存在。SSR标记分析结果显示,11对SSR引物中有6对引物在5对菌系组合的28个毒性谱不同的单孢子代菌系中,检测发现3个单孢菌系的扩增条带与其亲本菌系不同,且表现为亲本菌系扩增条带的重组,为体细胞重组菌系。这一结果从分子水平上证明了条形柄锈菌在室内接种条件下可以通过体细胞重组产生新小种而导致毒性变异。     

小麦抗条锈基因Yr69的连锁标记开发

抗条锈病基因Yr69对我国小麦条锈菌(Puccinia striiformis f.sp.tritici)小种具有广谱抗性,在小麦抗条锈病育种中具有重要价值.为提高分子标记辅助选择育种的效率,加快Yr69在小麦抗病育种中的应用,本研究利用条锈菌小种CYR34对包含340个小麦家系的'Taichung29/CH7086'...     

中国小麦条锈菌转主寄主小檗的鉴定

用萌发的小麦条锈菌冬孢子接种采自陕西省境内的陕西小檗、少齿小檗和长穗小檗,3种小檗均产生了性孢子器和锈孢子器。用人工接种小麦条锈菌冬孢子在陕西小檗上产生的锈孢子器接种小麦铭贤169产生了典型的条锈菌夏孢子堆症状。特异性PCR和DNA序列分析表明,人工接种产生于小檗上的锈孢子、接种锈孢子于小麦上产生的夏孢子堆与小麦条锈菌DNA的ITS区序列完全一致。更为重要的是,用采自田间受锈菌侵染的小檗叶片产生的锈孢子接种小麦铭贤169,经培养在小麦铭贤169叶片上产生了典型的条锈病症状。从而证实,在自然条件下,在中国,小檗不仅可作为小麦条锈菌的转主寄主,而且小麦条锈菌可在小檗上完成其有性繁殖过程。这一发现对进一步揭示我国小麦条锈菌高度的群体遗传多样性与毒性变异机理、完善小麦条锈病的防治策略具有十分重要的理论和实际意义。     

四川省小麦条锈菌群体遗传多样性的SSR分析

利用TP-M13-SSR自动荧光检测技术,对四川省小麦条锈菌群体遗传多样性水平进行了分析。研究结果表明,四川省小麦条锈菌群体遗传多样性比较丰富,地区之间存在明显的差异,川西北和四川盆地的种群遗传多样性相对较高,而四川西南部和四川东南部的种群遗传多样性较低。四川小麦条锈菌群体存在一定的遗传分化,地区间的遗传变异仅占14.92%,群体间的遗传变异占总变异的23.06%,群体内遗传变异占60.02%,遗传变异主要存在于群体内部。基因流和共享基因型从分子水平证实了四川小麦条锈菌在地区间的传播,且川西北和四川盆地之间的菌源交流最为广泛。     

Molecular mapping of stripe rust resistance gene YrSN104 in Chinese wheat line Shaannong 104

Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is a serious yield-limiting factor for wheat production worldwide. The objective of this study was to identify and map a stripe rust resistance gene in wheat line Shaannong 104 using SSR markers. F(1) , F(2) and F(3) populations from Shaannong 104/Mingxian 169 were inoculated with Chinese Pst race CYR32 in a greenhouse. Shaannong 104 carried a single dominant gene, YrSN104. Six potential polymorphic SSR markers identified in bulk segregant analysis were used to genotype F(2) and F(3) families. YrSN104 was closely linked with all six SSR markers on chromosome 1BS with genetic distances of 2.0 cM (Xgwm18, Xgwm273, Xbarc187), 2.6 cM (Xgwm11, Xbarc137) and 5.9 cM (Xbarc240). Pedigree analysis, pathogenicity tests using 26 Pst races, haplotyping of associated markers on isogenic lines carrying known stripe rust resistance genes, and associations with markers suggested that YrSN104 was a new resistance gene or an allele at the Yr24/Yr26 locus on chromosome 1BS. Deployment of YrSN104 singly or in combination to elite genotypes could play an effective role to lessen yield losses caused by stripe rust.     

1994 - 2002年小麦品种(系)抗条锈性鉴定与监测

1994—2002年经对3822份小麦品种(系)材料抗条锈性鉴定结果表明,冬小麦抗条锈性优于春小麦,甘肃品种抗条锈性优于国内其它省区品种。田间抗条锈性监测结果表明,我国主要生产品种均表现感病,甘肃主要生产品种仅陇鉴127等少数几个品种抗病,抗源材料中也仅有中四等少数品种表现抗病,结合抗病性鉴定、监测结果及田间综合农艺性状观察,筛选出20余份可供育种利用的抗源材料。同时在针对今后抗条中31、32号等主要小种类型的抗病育种、抗病性监测等方面进行了讨论。     

QTL identification and microphenotype characterisation of the developmentally regulated yellow rust resistance in the UK wheat cultivar Guardian

Yellow rust (causal agent: Puccinia striiformis f.sp. tritici) resistance in the UK wheat cultivar Guardian is developmentally regulated, resistance increasing as the plant matures. Yellow rust resistance was assessed under field conditions on plants after ear emergence to ensure maximum expression of resistance. Three quantitative trait loci (QTL) for yellow rust resistance were identified, being located on chromosomes 1B (QPst.jic-1B), 2D (QPst.jic-2D) and 4B (QPst.jic-4B). The largest resistance effect, QPst.jic-1B located to the same position on the long arm of chromosome 1B as the known durable source of yellow rust resistance, Yr29. Microscopic studies were carried out to determine what effect the resistance in Guardian had on the development of P. striiformis f.sp. tritici. While the adult plant resistance in Guardian did not prevent germinated urediniospores from establishing an effective infection site, the growth of hyphae within flag leaf tissue was significantly inhibited, slowing the development of microcolonies. 3,3-diaminabenzadine (DAB) and trypan blue staining indicated that this inhibition of hyphal growth was not associated with hydrogen peroxide accumulation or extensive plant cell death.     

The Use of Detached Seedling Leaves of Triticum aestivum to Study Pathogenicity in Puccinia recondita f. sp. tritici

A method is described for establishing isolates of Puccinia recondita f. sp. tritici (causal agent of brown rust of wheat) on detached seedling leaf segments. The method was used to compare the responses of leaf segments and intact seedling leaves for 28 differential genotypes inoculated with eight rust isolates. Leaf segments were incubated at two post-inoculation temperatures (17 and 23C) and intact seedlings at 20–25 C. Reliable determinations of isolate pathogenicity was obtained using detached leaf segments of wheats with genes Lr l. Lr2a, Lr3a, Lr3bg., Lr3ka, Lr9, Lr15, Lrl9. Lr20, Lr24, Lr25. Lr26, Lr28, and Lr30 at both post-inoculation temperatures, and for wheats with genes Lr2b. Lr2c, Lrl7, Lr23, Lr27 + Lr31 and LrH, at 23°C. Differences between leaf segments and intact leaves for the remaining eight differentials were attributed to inconsistent or poor expression of genes in detached leaf segments. By repeating tests with detached leaf segments, it was possible to establish the pathogenicities of the isolates on all of these differentials except those carrying Lr13, Lr14a, Lr16 and Lr18. Potential uses and limitations of the technique in studies of Puccinia recondita f. sp. tritici are discussed.     

QTL mapping of adult-plant resistances to stripe rust and leaf rust in Chinese wheat cultivar Bainong 64

Stripe rust and leaf rust, caused by Puccinia striiformis Westend. f. sp. tritici Erikss. and P. triticina, respectively, are devastating fungal diseases of common wheat (Triticum aestivum L.). Chinese wheat cultivar Bainong 64 has maintained acceptable adult-plant resistance (APR) to stripe rust, leaf rust and powdery mildew for more than 10?years. The aim of this study was to identify quantitative trait loci/locus (QTL) for resistance to the two rusts in a population of 179 doubled haploid (DH) lines derived from Bainong 64?×?Jingshuang 16. The DH lines were planted in randomized complete blocks with three replicates at four locations. Stripe rust tests were conducted using a mixture of currently prevalent P. striiformis races, and leaf rust tests were performed with P. triticina race THTT. Leaf rust severities were scored two or three times, whereas maximum disease severities (MDS) were recorded for stripe rust. Using bulked segregant analysis (BSA) and simple sequence repeat (SSR) markers, five independent loci for APR to two rusts were detected. The QTL on chromosomes 1BL and 6BS contributed by Bainong 64 conferred resistance to both diseases. The loci identified on chromosomes 7AS and 4DL had minor effects on stripe rust response, whereas another locus, close to the centromere on chromosome 6BS, had a significant effect only on leaf rust response. The loci located on chromosomes 1BL and 4DL also had significant effects on powdery mildew response. These were located at the same positions as the Yr29/Lr46 and Yr46/Lr67 genes, respectively. The multiple disease resistance locus for APR on chromosome 6BS appears to be new. All three genes and their closely linked molecular markers could be used in breeding wheat cultivars with durable resistance to multiple diseases.     

Rates of evolution of avirulence phenotypes and DNA markers in a northwest European population of Puccinia striiformis f. sp. tritici

The effects of evolutionary processes in fungal pathogen populations may occur more rapidly and display larger effects in agricultural systems than in wild ecosystems because of human involvement by plant breeding and crop management. In this study, we analysed the rate of evolution in three lineages of a northwest European population of a biotrophic and asexual reproduced fungal pathogen, Puccinia striiformis f. sp. tritici, causing yellow rust on wheat. Pathogen samples were collected between 1975 and 2002 in the UK and Denmark, and assayed for 14 individual avirulence/virulence alleles and up to 234 amplified fragment length polymorphism (AFLP) primer pairs producing approximately 17,000 AFLP fragments. The large number of fragments and a targeted sampling of isolates allowed a reconstruction of phylogenies in great detail, i.e. no homoplasy and a representation of sequential, evolutionary steps by pathogen samples. A recent, phenotypic loss of avirulence was observed at least once for loci corresponding to P. striiformis f. sp. tritici resistance Yr2, Yr3, Yr4, Yr7, Yr9, and Yr15, whereas Avr6 and Avr17 were lost independently in all three lineages, corresponding to 16 events of loss of avirulence (emergence of virulence). The opposite process, restoration of avirulence, was observed for Yr9 and Yr32. An interpretation of phenotypic changes within lineages as independent mutation events resulted in mutation frequencies from 1.4x10(-6) to 4.1x10(-6) per AFLP fragment (locus) per generation, whereas the effective rate by which a mutation from avirulence to virulence was established in the pathogen population, when subject to selection by host resistance genes, was approximately three orders of magnitude faster.     

小麦条锈菌分子生态学研究进展

小麦条锈病是危害最严重的小麦流行性病害之一,小麦条锈菌的生态学研究对制定合理的防治策略和抗锈育种具有重要意义.近十几年来,DNA分子标记技术被应用于小麦条锈菌的群体遗传学研究,推动了小麦条锈菌分子生态学研究的快速发展,为揭示小麦条锈菌的群体生态特性开辟了一个新的途径.本文系统介绍小麦条锈菌分子生态学研究的主要进展,并就我国当前研究的局限性和发展趋势进行了分析.     

兼抗白粉、条锈病小偃麦渗入系CH7124抗性遗传及细胞学鉴定

CH7124是通过八倍体小偃麦TAI8335与感病小麦杂交、回交育成的兼抗白粉病、条锈病的小偃麦种质系。利用抗性接种鉴定、细胞学和基因组原位杂交(GISH)技术相结合的方法,对CH7124的抗性来源、遗传方式及细胞学特征进行了分析和鉴定。结果表明,CH7124在苗期和成株期对条锈菌系CYR29、CYR31、CYR32、CYR33和白粉菌系E09、E20、E21、E26表现为免疫或近免疫,其抗性来自中间偃麦草,受1对显性核基因控制;CH7124的根尖细胞染色体数目为2n=42,花粉母细胞减数分裂中期I(PMC MI)绝大多数细胞内可观察到21个二价体,平均配对构型为2n=0.30 I+20.79 II+0.04 III;与普通小麦中国春、绵阳11的杂种F1中,有80%以上的花粉母细胞可观察到2n=21Ⅱ的染色体构型,其平均配对构型均为2n=21II。说明CH7124具有与普通小麦相似的染色体结构和规则的配对构型。由于利用以中间偃麦草总DNA为标记探针的原位杂交未观察到可见的外源DNA杂交信号,进一步证明CH7124是一个小麦-中间偃麦草的隐形异源渗入系。     

小麦秆锈菌生理小种21C3CPH和Ug99 SSR标记的筛选

小麦秆锈病是一种专化性很强的大区远距气传病害,曾造成多个小麦种植国家和地区的毁灭性损失,新的强毒力小种Ug99含有对Sr31等多个重要抗秆锈基因的联合毒性,对我国的小麦生产有巨大潜在威胁,因此,加强小麦秆锈菌生理小种的监测和鉴定是有效防治该病害的基础性研究工作和关键环节。现代分子生物学的迅猛发展,为许多研究提供了新的方法和手段,分子标记技术在区分小麦秆锈菌生理小种方面显示了充分的可行性。本研究利用25对SSR引物对7个小麦秆锈菌主要生理小种进行DNA多态性分析,结果显示,所有特异引物对秆锈菌的扩增结果均呈现出丰富的多态性,秆锈菌的不同生理小种之间存在遗传差异。其中引物SSR180在21C3CPH中扩增出205bp的特异性条带;引物SSR6在Ug99中扩增出170bp的特异性条带,经过多次的重复试验,这些特异性条带均能够比较稳定地重复出现,说明引物SSR180和SSR6可用于小种21C3CPH和Ug99的特异性检测。     

Molecular mapping of a non-host resistance gene YrpstY1 in barley (Hordeum vulgare L.) for resistance to wheat stripe rust

Cultivated barley (Hordeum vulgare L.) is considered as a non-host or inappropriate host species for wheat stripe rust caused by Puccinia striiformis f. sp. tritici. Most barley cultivars show a broad-spectrum resistance to wheat stripe rust. To determine the genes for resistance to wheat stripe rust in barley, a cross was made between a resistant barley line Y12 and a susceptible line Y16. The two parents, F(1) and 147 BC(1) plants were tested at seedling stage with Chinese prevalent race CYR32 of Puccinia striiformis f. sp. tritici by artificial inoculation in greenhouse. The results indicated that Y12 possessed one dominant resistance gene to wheat stripe rust, designated YrpstY1 provisionally. A total of 388 simple sequence repeat (SSR) markers were used to map the resistance gene in Y12 using bulked segregant analysis. A linkage map, including nine SSR loci on chromosome 7H and YrpstY1, was constructed using the BC(1) population, indicating that the resistance gene YrpstY1 is located on chromosome 7H. It is potential to transfer the resistance gene into common wheat for stripe rust resistance.     

Phenotypic and Genotypic Characterization of Phytophthora infestans Isolates from China

A total of 288 (202 from potato and 86 from tomato) isolates of Phytophthora infestans were collected from 1998 to 2007 in China. The isolates were characterized based on mating type, in vitro metalaxyl sensitivity, virulence on potato differentials, allozymes of glucose-6-phosphate isomerase ( Gpi ), peptidase ( Pep ), and mitochondrial DNA (mtDNA) haplotype and examined by DNA-based simple sequence repeat (SSR) and random amplified polymorphic DNA (RAPD) fingerprinting. The majority (283 of 288) of the isolates were of the A1 mating type, the other three were the A2 mating type and two were the A1A2 mating type. Resistance to metalaxyl was frequently observed, with 248 (86.1%) resistant, 21 (7.3%) intermediate and 19 (6.6%) sensitive isolates identified. Virulence was assessed for 125 isolates on a set of 11 potato differentials and 61 races were detected. Most isolates were virulent on the differential genotype with gene R3, and all known virulence genes were found, with race 3.4.7.11 being the most common. This pattern did not appear to be associated with geographic origin, sample type, mating type or metalaxyl sensitivity. The dominant banding patterns for Gpi were 100/100/111 (176 isolates) and 100/100 (109 isolates), but genotypes 86/100 and 100/111 were also identified. All isolates tested were homozygous (100/100) at the Pep locus. The majority (205 of 288) of isolates tested was of mtDNA haplotype IIb, 76 were haplotype IIa and seven were the rare Ib haplotype. The genetic diversity of 60 representative isolates from China was assayed by two types of molecular markers, RAPD and SSR. A high level of polymorphism was found. The results demonstrated the diverse phenotypic and genotypic structure of the current populations of P. infestans in China.     

Selection of parents for crossing based on genotyping and phenotyping for stripe rust (Puccinia striiformis) resistance and agronomic traits in bread wheat breeding

Bread wheat (Triticum aestivum L.) germplasm consisting of 45 genotypes were clustered phenotypically using ten morphological traits and Area Under Disease Progress Curve (AUDPC) as measure of stripe rust resistance. The clustering was ratified by using twenty three molecular markers (SSR, EST and STS) linked to stripe rust (Puccinia striiformis f. sp. tritici) resistant QTLs. The aim was to asses the extent of genetic variability among the genotypes in order to select the parents for crossing between the resistant and susceptible genotypes with respect to stripe rust. The Euclidian dissimilarity values resulted from phenotypic data regarding morphological traits and AUDPC were used to construct a dendrogram for clustering the accessions. Using un-weighted pair group method with arithmetic means, another dendrogram resulted from the similarity coefficient values was used to distinguish the genotypes with respect to stripe rust. Clustering based on phenotypic data produced two major groups and five clusters (with Euclidian dissimilarity ranging from 244 to 16.16) whereas genotypic data yielded two major groups and four clusters (with percent similarity coefficient values ranging from 0.1 to 46.0) to separate the gene pool into highly resistant, resistant, moderately resistant, moderately susceptible and susceptible genotypes. With few exceptions, the outcome of both type of clustering was almost similar and resistant as well as susceptible genotypes came in the same clusters of molecular genotyping as yielded by phenotypic clustering. As a result seven genotypes (Bakhtawar-92, Frontana, Saleem 2000, Tatara, Inqilab-91, Fakhre Sarhad and Karwan) of diverse genetic background were selected for pyramiding stripe rust resistant genes as well as some other agronomic traits after hybridization.