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。     

甘肃天水地区小麦条锈菌自然群体DNA指纹分析

对1997—1999连续三年采自甘肃省天水地区16个地点的244个小麦条锈菌分离系进行了PSR331S3/Bg1Ⅱ指纹分析,共鉴定出表现型185个,遗传多样性Shannon指数M=4.467, 加权修正值M*=0.9106,显现出高度的遗传多样性水平;其中三个主要采样点凤凰、甘谷和麦积山病菌群体M值分别为3.5720、3.0268和3.4186,加权修正值M*分别为0.9330、0.8513和0.8610。三个群体之间的遗传分化系数GST=0.03167,显示出较低的遗传分化水平。本文以多拷贝的RFLP标记为手段,揭示了小麦条锈菌作为一种活体寄生的远程气传病原真菌,其越夏栖息地关键区(天水地区)自然群体存在丰富的遗传多样性,不同海拔生境对病菌群体结构有显著的影响。但是,地区内亚群体间分化水平很低,表明区域内菌源交流十分频繁。     

小麦新抗源贵农775抗条锈性特征与遗传分析

发掘并利用不同类型抗条锈病基因,构建区域间抗病基因多样性差异布局,是阻遏条锈菌大区域传播、实现小麦条锈病持续控制的重要策略。为了明确小麦新抗源贵农775抗条锈性特征和抗性遗传规律,为其合理布局应用提供依据,文章利用10个条锈菌菌系进行苗期分小种鉴定;构建贵农775与感病品种Avocet(S)杂交后代F2:3及回交BC1遗传群体,利用小麦条锈菌流行小种CYR32和最近发现的对Yr26基因有毒性的新致病类型CH42,对贵农775进行抗条锈性遗传分析。结果表明,贵农775对包括CH42致病类型在内的所有10个供试菌系均表现为免疫或近免疫的抗病性反应,而中国当前主要条锈病抗源品种92R137、川麦42(YrCH42)、贵农22(YrGN22)及Yr24等均不抗CH42;抗病遗传分析结果表明,贵农775对小麦条锈菌小种CYR32和CH42的抗性分别由一对显性核基因控制,并且为不同的小种专化抗性基因。     

隐匿柄锈菌(小麦叶锈病菌)UP-PCR遗传多样性分析

小麦叶锈病是世界麦区普遍发生的病害。以2008年采集于河北省的29个隐匿柄锈菌(小麦叶锈病菌)单孢子堆分离菌系为试验材料,利用39个小麦抗叶锈近等(单)基因系和7个UP-PCR(Universally Primed PCR)引物对其进行毒性多态性和分子多态性分析。7个UP-PCR引物共检测出48条条带,其中多态性条带41条,多态性百分率为85.42%,表明UP-PCR在隐匿柄锈菌中扩增多态性较高;经聚类分析,遗传相似系数为0.69–0.90,在相似系数0.72处,29个叶锈菌株聚为6组,体现了隐匿柄锈菌菌株间的亲缘关系和差异性,表明UP-PCR技术可用于小麦叶锈病菌群体遗传多样性研究。在物种水平上,隐匿柄锈菌观察等位基因数(Na)为1.85,有效等位基因数(Ne)为1.29,Nei’s基因多样性指数(H)为0.19,Shannon信息指数(I)为0.31,多态位点百分率(P)为85.42%,表明隐匿柄锈菌遗传多样性丰富,其中沧州的群体遗传多样性水平最高,群体内多样性大于群体间多样性。聚类分析表明沧州和石家庄的病菌群体亲缘关系最近,邢台与石家庄的群体亲缘关系最远。隐匿柄锈菌UP-PCR多态性与毒性多态性间无明显相关性,且两者均与地理来源无相关性。     

不同海拔高度大血藤群体遗传多样性的RAPD分析及其与环境因子的相关性

利用 RAPD技术分析了分布于浙江省天台山 3个不同海拔高度的天然大血藤群体的遗传多样性、遗传分化以及与环境因子的相关性。 13种随机引物在 3 6株个体中共检测到 88个可重复的位点 ,其中多态位点 74个 ,总多态位点百分率为84.0 9% ,大血藤具有丰富的遗传多样性。 Shannon信息指数显示的遗传多样性以海拔 950 m的群体为最高 ,其次是海拔 73 0 m的群体 ,最低的是海拔 52 0 m的群体 ;群体内的遗传多样性占总遗传多样性的 43 .68% ,群体间的遗传多样性占 56.3 2 %。 Nei指数估计大血藤群体间的遗传分化系数为 0 .540 6,大血藤群体间的基因流很低。大血藤海拔 73 0 m群体与海拔 52 0 m群体的遗传相似度较高 ,海拔 950 m群体与其它两群体的遗传相似度较低。大血藤群体内的遗传多样性与土壤总氮呈极显著的正相关。     

松杨栅锈菌遗传多样性初步分析

采用ITS-nrDNA-RELP、测序技术、RAPD(随机扩增多态性DNA)分子标记技术,对我国松杨栅锈菌不同地域的5个生理小种11个菌系进行了遗传多样性分化研究.结果表明,该菌在我国的遗传分化与地理来源相关,可分为西部地理群和北方地理群.西部地理群又可分为高山森林生态型(HMF)和平原生态型(WPL).小种遗传分化不一定与致病性分化一致.t检验表明,各生理小种RAPD遗传多样性指数无明显差异,高山森林小种遗传多样性指数(0.5172)略高于平原小种遗传多样性指数(0.5089).核糖体基因转录间隔区高度保守,不适合该菌种内群体遗传多样性分化研究.     

基于cyt b基因的假眼小绿叶蝉11个地理种群遗传分化研究

应用特异性引物扩增假眼小绿叶蝉（Empoasca vitis G?the）56个不同地理种群Cytb基因片段,探讨了11个地理种群间的遗传多样性、分子变异、遗传分化程度及基因流水平,测序结果表明56条序列存在236个变异位点,45个单倍型。分析得出：（1）11个地理种群群体单倍型多样度 Hd 为0.978 79,群体的Hd范围为0.933 3~1.000 0,总群体和各种群的中性检验结果均不显著,其进化模型为中性模型。（2）总群体遗传分化系数 Gst 与固定系数 Fst 分别为0.017 03与0.165 47。种群间基因流Nm为1.26,较频繁基因交流减小了遗传差异,不存在明显的地理分化效应。     

基于线粒体COI序列变异的高原鼢鼠种群遗传分化研究

基于线粒体COI基因序列对高原鼢鼠7个地理种群的遗传多样性、遗传分化和基因流进行分析,158条COI基因序列中发现了570个变异位点,界定了54个COI单倍型。总体单倍型多样性指数Hd为0.911,种群单倍型多样性在0.278—0.964之间,高原鼢鼠的种群遗传多样性较高。群体总的遗传分化系数Fst为0.611,群体间的基因流Nm在-0.020—3.700之间,部分地理种群之间的遗传分化程度高,基因流弱。AMOVA分子变异分析显示,高原鼢鼠的遗传变异主要来自种群之间(77.56%),种群内部的遗传变异较低(22.44%)。中性检验(P0.01)与错配分析显示高原鼢鼠种群经历了群体扩张事件。IBD未检测到地理距离与种群间遗传距离的显著性相关关系(R2=0.124,P=0.118)。综合分析认为,高原鼢鼠不同地理种群间遗传分化的原因除地理隔离外,还与迁移扩散方式、进化过程和其他环境因素有关。     

北京东灵山地区不同海拔柴胡居群的遗传多样性

利用ISSR技术对北京东灵山地区不同海拔的6个柴胡居群进行分析,观察不同海拔柴胡居群的遗传多样性。结果表明,东灵山地区不同海拔柴胡居群的遗传多样性差异较大,海拔1135m居群表现出较高的遗传变异水平,高海拔居群遗传多样性较低;遗传距离与海拔差距有一定的相关性,相邻海拔的不同柴胡居群间具有相对较低的遗传距离;柴胡具有较强的遗传分化趋势,且大部分变异存在于居群内。不同海拔导致的异质生境及基因流是影响柴胡居群遗传多样性的主要原因。     

白皮松天然群体遗传结构的地理变异分析

为探讨白皮松天然群体遗传结构在地理分布上的差异,利用7对SSR引物对5个白皮松分布区域的遗传结构进行了分析。结果表明：7对SSR引物在5个区域内476个单株中共检测到14个多态性位点。各区域间观测等位基因数（Na）、有效等位基因数（Ne）、Shannon’s 信息指数（I）、观测杂合度（Ho）、期望杂合度（He）、Nei’s期望杂合度（Nei’s）分别介于1.7143~2.1429、1.1942~1.571、0.1948~0.4954、0.1726~0.3116、0.1178~0.3325、0.1172~0.3307之间。白皮松遗传多样性水平总体较低,区域间差异较大;遗传多样性水平最高的区域为秦岭西侧群体,其次为大巴山区群体;太行山与吕梁山群体多样性水平相对较低。区域间的遗传分化系数Fst介于0.0138~0.2242之间,基因流Nm介于0.865~17.8646之间。遗传分化较大、基因流水平较低的区域均发生在秦岭西侧及其与其他区域之间。各区域间遗传相似系数在0.8416~0.9964之间,遗传相似度最高的群体为太行山与吕梁山区域,遗传距离最大的为太行山与秦岭西侧区域。白皮松多样性分布的中心主要存在于秦岭西侧和大巴山区域,因此应对该区域进行重点保护。     

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。     

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.     

Cloning and characterization of the actin gene from Puccinia striiformis f. sp. tritici

The fungus Puccinia striiformis f. sp. tritici, the causal agent of wheat stripe rust, is an obligate biotrophic basidiomycete. Urediniospores are the most common spore type involved in the epidemiology of this disease. Tip growth of germ tubes of germinated urediniospores is a key step during infection of wheat, but few studies have investigated it so far. Recent research has found that actin is closely associated with hyphal tip growth. In this study, we have cloned and obtained the full-length actin cDNA from P. striiformis f. sp. tritici and characterized its expression. Furthermore, actin filament (F-actin) patterns were visualized microscopically during germ tube formation. The most conspicuous actin-containing structures were actin patches. They were mainly concentrated near the hyphal tip and scattered throughout the cortex. By using cytochalasin B, we observed that depolymerization of F-actin greatly reduced the germination rate of urediniospores and disrupted the transport of vesicles to the germ tube tip, indicating that F-actin played a key role in the tip growth of P. striiformis f. sp. tritici. This work helps us to understand the tip growth mechanism of P. striiformis f. sp. tritici, and may provide a theoretical framework for designing novel pesticides.     

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。     

Detection of Puccinia striiformis in Latently Infected Wheat Leaves by Nested Polymerase Chain Reaction

Stripe rust, caused by Puccinia striiformis f. sp. tritici ( Pst ), is one of the most devastating wheat diseases worldwide, especially in temperate regions with cool moist weather conditions. The identification of the pathogen in infected plants based on morphological or physiological criteria before sporulation is labour-intensive and time-consuming. To accelerate and simplify the process of detection, a nested Polymerase Chain Reaction (PCR) assay was developed for specific and sensitive detection of Pst . Specific primers Psta-Psts were designed according to a genome-specific sequence of Pst . In nested PCR, with a 10-fold dilution series of template DNA, the detection limit was 2 pg DNA in the first PCR with the primers Psta-Psts. The second round PCR was then performed using amplified products from the first PCR as the template and Nesta-Nests as the primers. An amplification signal was detectable even when only 2 fg of P. striiformis f. sp. tritici DNA was used as the template in nested PCR. With nested PCR, the sensitivity of detection was enhanced 1000 fold. Using extracts from stripe rust-infected wheat leaves, the fungus could be determined in the leaves before symptom appearance. The assay provides a rapid and sensitive method for detection of P. striiformis f. sp. tritici in latently infected leaves of overwintering wheat plants.     

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.     

Resistance gene analogs within an introgressed chromosomal segment derived from Triticum ventricosum that confers resistance to nematode and rust pathogens in wheat

A resistance (R) gene-rich 2S chromosomal segment from Triticum ventricosum contains a cereal cyst nematode (CCN; Heterodera avenae) R gene locus CreX and a closely linked group of genes (Sr38, Yr17, and Lr37) that confer resistance to stem rust (Puccinia graminis f. sp. tritici), stripe rust (P. striiformis f. sp. tritici), and leaf rust (P. recondita f. sp. tritici) when introgressed into wheat. The 2S chromosomal segment from T. ventricosum is further delineated in translocations onto chromosome 2A of bread wheat, where the rust genes are retained but not the CreX gene. Using these critical genetic stocks, we have isolated family members of R gene analogs that are associated with either the 2S segment from T. ventricosum carrying the CreX locus or the rust genes. Derivatives of the Cre3 candidate R gene sequence and a rice (Oryza sativa) R gene analog that mapped to the 2S homologous chromosome groups in wheat were used to isolate related gene sequences from T. ventricosum that contain a nucleotide binding site-leucine rich repeat domain. The potential of these gene sequences as entry points for isolating candidate genes or gene family members of the CreX or rust genes and their further applications to plant breeding are discussed.     

Molecular markers for leaf rust resistance genes in wheat

Over 100 genes of resistance to rust fungi: Puccinia recondita f. sp. tritici, (47 Lr - leaf rust genes), P. striiformis (18 Yr - yellow rust genes) and P. graminis f. sp. tritici (41 Sr - stripe rust genes) have been identified in wheat (Triticum aestivum L.) and its wild relatives according to recent papers. Sixteen Lr resistance genes have been mapped using restriction fragments length polymorphism (RFLP) markers on wheat chromosomes. More than ten Lr genes can be identified in breeding materials by sequence tagged site (STS) specific markers. Gene Lrk 10, closely linked to gene Lr 10, has been cloned and its function recognized. Available markers are presented in this review. The STS, cleaved amplified polymorphic sequence (CAPS) and sequence characterized amplified regions (SCAR) markers found in the literature should be verified using Triticum spp. with different genetic background. Simple sequence repeats (SSR) markers for Lr resistance genes are now also available.     

Spore traps network: a new tool for predicting epidemics of wheat yellow rust

A network of Burkard 7-day spore-recording traps was set up in the Walloon Region in Belgium to monitor the airborne inoculum of wheat pathogens. The relationship between the airborne inoculum of Puccinia striiformis f.sp. tritici, the causal agent of stripe rust, and the disease incidence on plants in untreated plots located near each spore traps was studied during the 2008-2009 season. The presence of airborne inoculum was tested in four locations on tapes collected from the Burkard spore traps from 1 April to 14 June 2009. Total DNA from each fragment of spore trap tape corresponding to 1 day sampling was extracted. P. striiformis f.sp. tritici was quantified by real-time polymerase chain reaction (PCR) assay using specific primers and SYBRGreen. The airborne inoculum of P. striiformis was first detected between 7 and 13 April 2009, depending on the location in the Walloon Region. The first symptoms of stripe rust were observed in the fields between 15 May and 2 June 2009. The onset of the disease symptoms was always preceded by a higher peak of airborne inoculum about 15 days earlier. When P. striiformis f.sp. tritici was detected, the daily quantities of spores, collected from a volume of air of 14.4 m3, fluctuated between 0.23 and 154.66. This study shows that spore traps coupled with real-time PCR could be used to assess the airborne inoculum of P. striiformis in order to understand and predict stripe rust outbreaks.