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1.
Gordon SG Kowitwanich K Pipatpongpinyo W St Martin SK Dorrance AE 《Phytopathology》2007,97(1):113-118
ABSTRACT Molecular analysis of sources of resistance to plant pathogens should expedite and confirm novel gene discovery and consequently the development of disease resistant cultivars. Recently, soybean plant introductions (PIs) were identified that contain putative novel Rps genes for resistance to Phytophthora sojae. The number of resistance genes that confer resistance to P. sojae isolates OH17 (1b,1d,2,3a,3b,3c,4,5,6,7) and OH25 (1a,1b,1c,1k,7) was then determined in several of the PIs. The objective of this study was to determine if the Rps genes present in these PIs were associated with eight described Rps loci that have been mapped on soybean molecular linkage groups F, G, J, and N. Nine F(2:3) soybean populations were genotyped with simple sequence repeat (SSR) markers linked to previously mapped Rps loci. The nine PI populations all had SSR markers associated (P < 0.01) with resistance to P. sojae isolate OH17 in the Rps1 region. Rps1c is a likely candidate in eight PIs but novel genes may also be possible, while novel genes may confer resistance in one PI to P. sojae isolate OHI7. Two or more Rps genes, including some that are potentially novel, confer resistance to P. sojae isolate OH25 in eight of the populations. However, based on the response to these two isolates, virulence already exists for at least some of the novel genes identified in this study. 相似文献
2.
ABSTRACT Phytophthora root and stem rot of soybeans caused by Phytophthora sojae is a serious limitation to soybean production in the United States. Partial resistance to P. sojae in soybeans is effective against all the races of the pathogen and is a form of incomplete resistance in which the level of colonization of the root is reduced following inoculation. Other forms of incomplete resistance include the single dominant gene Rps2 and Ripley's root resistance, which are both race-specific. To differentiate partial resistance from the other types of incomplete resistance, the components lesion length, numbers of oospores, and infection frequency were measured in eight soybean genotypes inoculated with two P. sojae isolates. The Rps2 and root-resistant genotypes had significantly lower oospore production and infection frequency compared with the partially resistant genotype Conrad, while the root-resistant genotype also had significantly smaller lesion lengths. However, the high levels of partial resistance in Jack were indistinguishable from Rps2 in L76-1988, based on the evaluation of these components. Root resistance in Ripley and Rps2 in L76-1988 had similar responses for all components measured in this study. Partial resistance expressed in Conrad, Williams, Jack, and General was comprised of various components that interact for defense against P. sojae in the roots, and different levels of each component were found in each of the genotypes. However, forms of incomplete resistance expressed via single genes in Ripley and Rps2 in L76-1988, could not be distinguished from high levels of partial resistance based on lesion length, oospore production, and infection frequency. 相似文献
3.
大豆疫霉根腐病是大豆的毁灭性病害。为了深入了解大豆对疫霉菌的分子抗病机制,以大豆疫霉菌1号生理小种游动孢子接种抗性品种绥农10的根部及下胚轴,通过反转录差异显示技术分离到疫霉菌侵染0、0.5、1、2和4h后大豆下胚轴和茎部的差异表达基因,其中至少有8个基因与抗病相关。接种后0.5 h开始上调表达的有肉桂酸-4-羟化酶基因、ATP合成酶β亚基基因,以及类花生泛素结合酶基因;接种后1h和2h依次开始上调表达的有尿苷二磷酸-N-乙酰基-α-D-氨基半乳糖基因和豌豆蓝铜蛋白基因;接种后4 h才上调表达的有TGA型碱性亮氨酸拉链基因、大豆环孢素基因和14-3-3蛋白基因。这8个基因中有1个基因与信号传导有关、4个基因与抗病和防御有关、2个基因与转录调控有关、1个基因与能量代谢有关。研究表明,以上8个基因在疫霉菌游动孢子萌发、侵入大豆和在大豆体内扩展过程中起着重要作用。 相似文献
4.
ABSTRACT Root and stem rot caused by Phytophthora sojae is one of the most destructive diseases of soybean (Glycine max) worldwide. P. sojae can survive as oospores in soil for many years. In order to develop a rapid and accurate method for the specific detection of P. sojae in soil, the internal transcribed spacer (ITS) regions of eight P. sojae isolates were amplified using polymerase chain reaction (PCR) with the universal primers DC6 and ITS4. The sequences of PCR products were aligned with published sequences of 50 other Phytophthora species, and a region specific to P. sojae was used to design the specific PCR primers, PS1 and PS2. More than 245 isolates representing 25 species of Phytophthora and at least 35 other species of pathogens were used to test the specificity of the primers. PCR amplification with PS primers resulted in the amplification of a product of approximately 330 bp, exclusively from isolates of P. sojae. Tests with P. sojae genomic DNA determined that the sensitivity of the PS primer set is approximately 1 fg. This PCR assay, combined with a simple soil screening method developed in this work, allowed the detection of P. sojae from soil within 6 h, with a detection sensitivity of two oospores in 20 g of soil. PCR with the PS primers could also be used to detect P. sojae from diseased soybean tissue and residues. Real-time fluorescent quantitative PCR assays were also developed to detect the pathogen directly in soil samples. The PS primer-based PCR assay provides a rapid and sensitive tool for the detection of P. sojae in soil and infected soybean tissue. 相似文献
5.
引起大豆疫霉根腐病的大豆疫霉菌(Phytophthora sojae)是危害大豆的破坏性病原菌之一,也是我国重要的检疫性植物病原菌。简单、快速、准确的鉴定和检测技术是阻止大豆疫霉菌传入和病害早期诊断的有效工具。本研究从大豆疫霉菌细胞色素氧化酶基因Ⅱ(coxⅡ)序列和两个激发素(elicitin)家族基因EST序列中开发了3对大豆疫霉菌特异引物:Cox3-F/Cox3-R、PSEL1-F/PSEL1-R和PSEL2-F/PSEL2-R。这3对引物在大豆疫霉菌中分别扩增出450、289bp和370bp的特异性片段,其检测大豆疫霉菌基因组DNA的灵敏度分别为20、2pg/μL和2pg/μL。3对引物能够有效检测大豆疫霉菌侵染的大豆病株,可以用于病害诊断和鉴别。 相似文献
6.
β-1,3-葡聚糖酶和几丁质酶活性与大豆对疫霉根腐病抗性的关系 总被引：5，自引：1，他引：4
为了明确β-1,3-葡聚糖酶和几丁质酶与大豆抗疫霉根腐病的关系,测定了不同抗性大豆品种接种大豆疫霉菌后β-1,3-葡聚糖酶和几丁质酶活性的变化情况和2种酶对大豆疫霉菌的抑制作用。结果表明,大豆疫霉菌能诱导大豆β-1,3-葡聚糖酶和几丁质酶的活性增强,但2种酶在积累速度和幅度上,抗病品种和感病品种有显著的差异。与感病品种"857-1"相比,抗病品种"垦农4号"2种酶活性不仅升高的速度快、幅度大,且高活性维持的时间长。β-1,3-葡聚糖酶和几丁质酶混合液对大豆疫霉菌的菌丝生长、孢子囊形成和孢子萌发的抑制作用明显,其次是β-1,3-葡聚糖酶,而几丁质酶对大豆疫霉菌的抑制作用不明显。表明大豆对大豆疫霉根腐病的抗性与β-1,3-葡聚糖酶和几丁质酶的活性呈正相关关系。β-1,3-葡聚糖酶和几丁质酶混合对大豆疫霉菌的抑制具有协同增效作用。 相似文献
7.
福建省大豆疫病病原鉴定及其核糖体DNA-ITS序列分析 总被引：35，自引：3，他引：35
从福建省龙海大豆根腐病株上分离的疫霉菌株中,选取6个代表菌株,对病原菌进行了形态特征、致病性、寄主范围鉴定及核糖体DNA-ITS序列分析,结果表明,该菌为疫霉属真菌,在黑麦琼脂培养基上生长缓慢,菌丝致密、无隔,形成菌丝膨大体,近直角分支,分支处稍缢缩。水培后产生大量椭圆形孢子囊,不形成乳突,通过内层出方式产生新孢子囊,游动孢子在孢子囊内形成,同宗配合,藏卵器球形,雄器侧生;接种后可出现典型的大豆疫病症状;人工接种只侵染大豆、豇豆和菜豆等少数豆科植物。其核糖体DNA-ITS序列分析表明,分离菌株与GenBank中大豆疫霉的ITS序列的同源性均为99.8%,仅有2个碱基的差异,结合形态特征和致病性测定,将这些病原菌鉴定为Phytophthora sojae. 这是首次报道大豆疫霉菌在福建省存在。 相似文献
8.
大豆疫霉根腐病是大豆破坏性病害之一。利用抗病品种是防治该病的唯一有效的方法。迄今,已经鉴定了15个抗大豆疫霉根腐病基因(Rps基因),而且大豆部分基因都获得了不同类型的分子标记。本研究根据以前抗病基因推导结果选择26个可能含有Rps1基因座位等位基因或(和)Rps4基因的大豆品种(系),利用分别与Rps1a和Rps4紧密连锁的SSR标记进行抗病基因的分子检测,通过比较含有已知抗病基因对照大豆品种(系)分子标记检测结果并综合以往基因推导结果推断检测品种(系)的Rps基因。在选择的26个品种(系)中,长农14号被证明含有Rps1a,周豆13和铁95068-5含有Rps1a与Rps4基因组合,品系50794、科8924-3和合豆1号含有Rps4;有11个品种(系)存在含有Rps1a的证据、品系50052被推断含有Rps1c与Rps3b基因组合,但不排除这些品种(系)在Rps1座位含有一个新等位基因的可能性。另外,有7个品种(系)的所含抗病基因不能确定,它们可能含有新的Rps基因。 相似文献
9.
Characterization and Distribution of Two Races of Phialophora gregata in the North-Central United States 总被引：1，自引：0，他引：1
ABSTRACT Genetic variation and variation in aggressiveness in Phialophora gregata f. sp. sojae, the cause of brown stem rot of soybean, was characterized in a sample of 209 isolates from the north-central region. The isolates were collected from soybean plants without regard to symptoms from randomly selected soybean fields. Seven genotypes (A1, A2, A4, A5, A6, M1, and M2) were distinguished based on DNA fingerprinting with microsatellite probes (CAT)(5) and (CAC)(5), with only minor genetic variation within the A or M genotypes. Only the A1, A2, and M1 genotypes were represented by more than one isolate. The A genotypes dominated in the eastern Iowa, Illinois, and Ohio samples, whereas the M genotypes were dominant in samples from western Iowa, Minnesota, and Missouri. In growth chamber experiments, isolates segregated into two pathogenicity groups based on their aggressiveness toward soybean cvs. Kenwood and BSR101, which are relatively susceptible and resistant, respectively, to brown stem rot. In both root dip inoculation and inoculation by injecting spores into the stem near the ground line (stab inoculations), isolates of the A genotypes caused greater foliar symptoms and more vascular discoloration than isolates of the M genotypes on both cultivars of soybean. All isolates caused foliar symptoms in both cultivars and in three additional cultivars of soybean with resistance to brown stem rot. Greater differences between the A and M genotypes were seen in foliar symptoms than in the linear extent of xylem discoloration, and greater differences were seen in Kenwood than in BSR101. Inoculation of these genotypes into five cultivars of soybean with different resistance genes to brown stem rot showed a genotype x cultivar interaction. A similar distinction was found in an earlier study of the adzuki bean pathogen, P. gregata f. sp. adzukicola, and consistent with the nomenclature of that pathogen, the soybean pathogens are named the aggressive race (race A) and the mild race (race M) of P. gregata f. sp. sojae. 相似文献
10.
大豆疫霉根腐病 总被引：15，自引：2，他引：13
大豆疫霉根腐病是毁灭性病害之一,在我国近年有加重发展趋势。美国、澳大利亚和加拿大对Phytophthora sojae及大豆抗性研究较多,目前已建立了完善的生理小种体系,分离了30多个生理小种,最新定名小种为38和39号。RFLP研究表明,P.sojae的多数变异都可在小种1,7,17和19号中表现出来,因而推测其它小种可能是从这4个小种杂交派生而来,澳大利亚的P.sojae由美国传入。抗、耐病筛选方法有田间筛选法、接种体薄层法、斜板法、下胚轴接种法和豆荚接种法等。选出不少抗病材料,通过遗传研究定名了抗性基因Rps1、Rps-b、Rps-c、Rps1-d、Rps1-k、Rps2、Rps3、Rps3-b、Rps3-c、Rps4、Rps5、Rps6和Rps7等。Rps1-k是目前应用较广的抗性基因,它能抗20多个生理小种。抗性基因Rps1和Rps1-c从被利用到丧失抗性大约是8~10年的时间,按此推算几年之内Rps1-k基因也将丧失抗性,因此主张抗病基因和耐病基因结合使用,不同抗性基因结合使用。 相似文献
11.
Ranathunge K Thomas RH Fang X Peterson CA Gijzen M Bernards MA 《Phytopathology》2008,98(11):1179-1189
Phytophthora sojae is the causal agent of root and stem rot of soybean (Glycine max). Various cultivars with partial resistance to the pathogen have been developed to mitigate this damage. Herein, two contrasting genotypes, the cultivar Conrad (with strong partial resistance) and the line OX760-6 (with weak partial resistance), were compared regarding their amounts of preformed and induced suberin components, and to early events during the P. sojae infection process. To colonize the root, hyphae grew through the suberized middle lamellae between epidermal cells. This took 2 to 3 h longer in Conrad than in OX760-6, giving Conrad plants more time to establish their chemical defenses. Subsequent growth of hyphae through the endodermis was also delayed in Conrad. This cultivar had more preformed aliphatic suberin than the line OX760-6 and was induced to form more aliphatic suberin several days prior to that of OX760-6. However, the induced suberin was formed subsequent to the initial infection process. Eventually, the amount of induced suberin (measured 8 days postinoculation) was the same in both genotypes. Preformed root epidermal suberin provides a target for selection and development of new soybean cultivars with higher levels of expression of partial resistance to P. sojae. 相似文献
12.
防治大豆疫霉根腐病的药剂筛选 总被引：14，自引：0，他引：14
在离体条件下测定了 8种内吸性杀菌剂对大豆疫霉菌菌丝生长的抑制作用。甲霜灵、甲霜灵锰锌、安克锰锌、杀毒矾、霜脲锰锌、克露和加瑞农为有效杀菌剂 ,霜霉威不具有抑菌效果。甲霜灵的 EC50 值为0 .4 870 μg/ m L,抑菌效果最好 ,安克锰锌、甲霜灵锰锌的 EC50 值分别为 1.4 2 6 1μg/ m L和 1.76 97μg/ m L,效果次之。在活体条件下 ,甲霜灵和甲霜灵锰锌能完全抑制大豆疫霉菌对感病大豆品种的侵入 ,并具有较长的药效期 ,安克锰锌、杀毒矾和霜霉威虽然具有明显的防治效果但药效期很短。大豆疫霉菌菌株间对甲霜灵锰锌的敏感性存在差异 ,但这种差异与菌株来源没有相关性 ,EC50 平均值为 1.830 2μg/ m L ,没有发现耐药性菌株。在我国黑龙江省目前缺乏有效抗病品种的情况下 ,建议应用甲霜灵锰锌防治大豆疫霉根腐病。 相似文献
13.
ABSTRACT The prevalence of brown stem rot (caused by Phialophora gregata), Heterodera glycines, and Phytophthora sojae in the north central United States was investigated during the fall of 1995 and 1996. Soybean fields were randomly selected using an area-frame sampling design in collaboration with the National Agricultural Statistics Service. Soil and soybean stem samples, along with tillage information, were collected from 1,462 fields in Illinois, Iowa, Minnesota, Missouri, and Ohio. An additional 275 soil samples collected from Indiana were assessed for H. glycines. For each field, the incidence and prevalence of brown stem rot was assessed in 20 soybean stem pieces. The prevalence and recovery (expressed as the percentage of leaf disks colonized) of P. sojae and the prevalence and population densities of H. glycines were determined from the soil samples. The prevalence of brown stem rot ranged from 28% in Missouri to 73% in Illinois; 68 and 72% of the fields in Minnesota and Iowa, respectively, showed symptomatic samples. The incidence of brown stem rot was greater in conservation-till than in conventional-till fields in all states except Minnesota, which had few no-till fields. P. sojae was detected in two-thirds of the soybean fields in Ohio and Minnesota, whereas 63, 55, and 41% of the fields in Iowa, Missouri, and Illinois, respectively, were infested with the pathogen. The recovery rates of P. sojae were significantly greater (P 相似文献
14.
大豆疫霉根腐病菌单游动孢子的毒性遗传与变异 总被引：7，自引：1，他引：6
采用离体叶柄伤口接种法测定大豆疫霉根腐病菌44号生理小种单游动孢子连续3代或4代分离后代的毒性,结果表明:从S1中选择与亲本相比毒性不发生变异的1号单游动孢子菌株(44号生理小种)和变异最大的30号单游动孢子菌株(1号生理小种)继续分离2代或3代,单游动孢子毒性变异趋势主要是从44号生理小种变异为3号生理小种,也有变异成毒性公式为7或1a,7的单游动孢子。大豆疫霉根腐病菌无性世代毒性变异几率很高,多数单游动孢子毒性在分离后代中都发生变异,产生不同的小种或毒性公式,并且毒性变异基本不能稳定遗传。 相似文献
15.
ABSTRACT Investigations were conducted to determine whether the effects of tillage practices on the prevalence of brown stem rot of soybean (caused by Phialophora gregata), Heterodera glycines, and Phytophthora sojae were confounded by soil texture in samples collected in the fall of 1995 and 1996. Soil and soybean stem samples, along with tillage information, were collected from 1,462 randomly selected fields in Illinois, Iowa, Minnesota, Missouri, and Ohio in collaboration with the National Agricultural Statistics Service. The incidence of brown stem rot was determined from 20 soybean stem pieces collected from each field in a zigzag pattern. The detection frequency of P. sojae (expressed as percent leaf disks colonized) and population densities of H. glycines were determined from soil cores also collected in a zigzag pattern. The soil samples were grouped into various textural classes, and the effect of soil texture and tillage relations on the activities of each pathogen were determined. Both tillage and soil texture affected the incidence of brown stem rot; however, there was no interaction between tillage and soil texture. Conservation tillage had a greater (P < 0.05) incidence of brown stem rot in clay loam and silty clay loam than did conventional tillage. The detection frequency of P. sojae was not affected by tillage, but a tillage x texture interaction (P = 0.013) indicated that the effect of tillage depended on soil texture. There was a greater (P < 0.05) detection frequency of P. sojae in conservation tillage than in conventional tillage in silt loam and loam soils. However, in sandy loam, the detection frequency of P. sojae was greater (P = 0.0099) in conventional tillage than in conservation tillage. Population densities of H. glycines were significantly affected by both tillage and soil texture, but overall, there was no tillage x texture interaction. There was an inverse relationship between population densities of H. glycines and percent clay (r = -0.81, P = 0.01) in no-till fields, but little or no change in nematode densities was observed with increasing clay content in tilled fields. Population densities of H. glycines were less (P < 0.05) in no-till fields than in tilled fields in silty clay loam and clay soils. There was no difference in H. glycines densities between the tillage categories in soils sandier than silty clay loam or clay. The findings emphasize the need for cautious interpretation of the effects of tillage practices on diseases and pathogens in the absence of information on soil texture. 相似文献
16.
ABSTRACT Populations of Phytophthora spp. were determined by enzyme-linked immunosorbent assay (ELISA) in field soils used for pepper and soybean production in Ohio. Soybean fields were sampled extensively (64 fields, n = 6 samples per field over 2 years) and intensively (4 fields, n = 64 samples per field in 1 year) to assess heterogeneity of P. sojae populations. Four pepper fields (n = 64), three of which had a history of Phytophthora blight (caused by P. capsici), also were sampled intensively during a 6-month period. Mean (m), variance (v), and measures of aggregation (e.g., variance-to-mean ratio [v/m]) of immunoassay values, translated to Phytophthora antigen units (PAU), were related to the disease history in each of the pepper and soybean fields. Mean PAU values for fields in which Phytophthora root rot (soybean) or blight (pepper) had been moderate to severe were higher than in fields in which disease incidence had been low or not observed. A detection threshold value of 11.3 PAU was calculated with values for 64 samples from one pepper field, all of which tested negative for Phytophthora by bioassay and ELISA. Seven of the eight intensively sampled fields contained at least some detectable Phytophthora propagules, with the percentage of positive samples ranging from 1.6 to 73.4. Mean PAU values ranged from 1 to 84 (extensive soybean field sampling), 6 to 24 (intensive soybean field sampling), and 4 to 30 (intensive pepper field sampling); however, variances ranged from 0 to 7,774 (extensive sampling), 30 to 848 (intensive soybean field sampling), and 5 to 2,401 (intensive pepper field sampling). Heterogeneity of PAU was high in most individual soybean and pepper fields, with values of v/m greater than 1, and log(v) increasing with log(m), with a slope of about 2.0. Spatial autocorrelation coefficients were not significant, indicating there was no relationship of PAU values in neighboring sampling units (i.e., field locations) of the intensively sampled fields. Combined results for autocorrelations and v/m values indicate that Phytophthora was highly aggregated in these fields but that the scale of the aggregation (e.g., average focus size) was less than the size of the sampling units. Because of the observed variability, we calculated that sample sizes of 20 or more would be needed to estimate precisely the mean density of Phytophthora in most cases. 相似文献
17.
中国大豆疫霉根腐病和大豆种质抗病性研究 总被引：19，自引：2，他引：17
大豆疫霉根腐病在中国的发生区域逐渐扩大,局部地区发生严重。大豆疫霉菌1号生理小种是黑龙江省的优势小种,同时也存在其它已知生理小种和新生理小种。不同大豆生态区之间大豆疫霉菌生理小种差异显著。在总体上,中国大豆种质的抗病性不强,长江流域大豆中抗病种质比率最高,其次为黄淮海流域种质,而东北地区抗病种质较少。按省归类,大豆种质抗性由强至弱依次为河南、江苏、湖北、山西、河北、辽宁、吉林、黑龙江、山东。吉林和黑龙江选育推广品种中,感病品种分别高达80%和73%;在462份大豆品系中,也表现出南方材料抗病性高于北方材料的趋势;地方品种中感病类型也高达60%以上。 相似文献
18.
安徽省大豆疫霉根腐病菌的鉴定及rDNA-ITS序列分析 总被引：1，自引：0，他引：1
为明确安徽省夏大豆疫霉根腐病的病原菌种类,对采集自涡阳、怀远、固镇3个县的夏大豆病株及土样分离纯化后获得28株菌株,选取6株代表性菌株,通过形态学观察及核糖体DNA-ITS序列分析对其进行鉴定,并测定了其致病型。结果表明,6株菌株在利马豆培养基上菌落白色,质地均匀;菌丝无隔,致密,具近直角分枝;在10%V8C培养液中,游动孢子囊顶生,不脱落,卵形至椭圆形,无明显乳突,有内层出现象,长宽比大于1.6∶1;同宗配合,在利马豆培养基上单株培养产生大量卵孢子,藏卵器球形,雄器大多侧生;接种合丰35大豆品种后出现典型的大豆疫霉根腐病症状。r DNA-ITS序列分析表明,6株菌株与Gen Bank中大豆疫霉Phytophthora sojae的ITS序列同源性高达100%;菌株GY4、GY8、HY11、HY16、GZ10、GZ21的毒力公式分别为1b,2,3a,3b,4,5,6,7;1b,1d,3a,3b;1d,3a,3b,3c,4,5,6,7;2,3c,4,5,6,7;1b,3a,3c,5,8;3a,3b,5,6,7,8;属于6个不同的致病型。研究表明,这6株菌株均为大豆疫霉。 相似文献
19.
本研究旨在建立一个适于分析大豆遭受大豆疫霉菌侵染后基因表达研究的互作体系。在比较了15个携带不同抗病基因的大豆基因型的组织培养情况和7个大豆疫霉菌分离物及其游动孢子单孢系的毒力变化的基础上,构建了大豆悬浮细胞和大豆疫霉菌游动孢子的共培养体系,进而分析了共培养过程中大豆细胞的活力和防御基因表达情况。结果表明,不同亲和力菌株的游动孢子引起的大豆细胞活力变化十分相似;非亲和菌株的游动孢子可诱导寄主防御基因的表达发生变化。此系统为深入开展大豆抗性机制研究提供了良好的平台。 相似文献
20.
Phytophthora sojae is a destructive soilborne pathogen causing seedling damping‐off and root rot of soybean (Glycine max). The goal of this study was to determine the genetic structure of P. sojae populations in Fujian, China. Nine microsatellite markers were used to investigate the genetic variation in 19 P. sojae populations, sampled from Fujian Province and northeastern China (Jilin and Heilongjiang Provinces) between 2002 and 2013. Overall, a low genetic diversity, Hardy–Weinberg disequilibrium, and an index (an index of association) that was significantly different from zero were detected in populations; these results were consistent with self‐fertilization and clonal modes of reproduction for this pathogen. However, using Bayesian Markov chain Monte Carlo approach, principal component analysis and neighbour joining (NJ) algorithm, the Fujian P. sojae populations clustered into three distinct groups, one of which included most isolates of the northeast populations. What is more, significant estimates of pairwise fixation indices (FST) were detected between most populations, especially in different clusters. It is hypothesized that the cropping system used, the limited dispersal ability, and human‐mediated gene flow may account for the observed genetic structure of P. sojae populations in Fujian, China. In addition, a high virulence frequency of the pathogen on different cultivars carrying known major R genes for resistance, and a rapid increase in virulence frequency, indicated that these major R genes should not be used to manage seedling damping‐off and root rot diseases of soybean (Glycine max). 相似文献