陕西省核盘菌不同分离株对油菜的致病性

采用带菌牙签活体茎秆穿刺接种法和离体叶片菌饼接种法,以3个品种的油菜为供试寄主,对陕西省5个地区10个县的油菜和其它5种寄主共495个核盘菌分离株进行了致病性测定。结果显示,两种接种方法接种3个不同油菜品种所反映的不同分离株的致病趋势一致。离体叶片菌饼接种蓉油12号除来自勉县和城固县的2个分离株不能致病外,其余493个分离株均能致病,但各分离株所致病斑直径差异很大,为0.5～42.6mm,其中病斑直径在10～40mm的分离株占94.7%,属于优势群体。同一地区甚至同一地块均存在不同致病力的分离株,不同寄主来源的分离株在油菜离体叶片上均能致病。说明核盘菌种内存在明显的致病性分化,这种分化与地理来源和寄主来源均无明显的相关性。     

核盘菌致病性分化研究

为了解核盘菌的致病性分化,本研究用活体定位穿刺接种法,以油菜为供试寄主,对采自四川省10个地区23个县、9种寄主的108个菌株进行了致病性测定,结果表明,所有菌株对供试油菜品种均能致病,但各菌株所致病斑长度差异很大(2.7～82.0 mm),说明核盘菌种群内存在明显的致病性分化,这种分化与地理来源和寄主来源没有明显的关系。     

河北昌黎与广西资源两地区葡萄霜霉菌致病力分化分析

为明确河北昌黎、广西资源两地不同葡萄品种来源霜霉菌致病力分化情况,本研究利用离体叶盘接种法测定了河北、广西主栽品种‘红宝石无核’、‘红地球’及‘巨峰’来源葡萄霜霉病菌对不同鉴别寄主的致病力,观察不同地区、不同寄主来源病菌对同一感病材料以及同一寄主来源病菌对不同感病材料的致病力大小是否存在差异。结果表明:不同地区同一寄主来源病菌及同一来源不同菌株间致病力均存在差异,说明两个地区病菌群体间和群体内各菌株间均存在分化;两地不同寄主来源病菌群体对同一感病材料的致病力及同一寄主来源病菌群体对不同感病材料的致病力均存在显著差异,且广西资源地区菌株间差异性比河北昌黎地区更明显,说明不同寄主来源的菌株存在一定程度的分化。     

不同寄主来源的Monilinia fructicola对多菌灵的敏感性及其遗传结构特征

美澳型核果链核盘菌Monilinia fructicola (G. Winter) Honey是引起多种果树褐腐病的重要病原菌，多菌灵是防治该病害的重要杀菌剂。为明确不同寄主来源的菌株对多菌灵的敏感性及遗传结构差异，研究测定了来源于樱桃、李子和毛桃的17株菌株对多菌灵的敏感性，同时基于Tub2核苷酸序列分析了来源于樱桃和毛桃的32株M. fructicola群体的遗传多样性和群体分化特征。结果表明:来自樱桃、李子和毛桃的17株菌株中，多菌灵的EC₅₀< 1 μg/mL和 > 1 μg/mL的菌株比例分别为58.8%和41.2%，其中EC₅₀> 50 μg/mL的菌株比例为17.6%。来自毛桃的菌株群体多样性比来自樱桃的高，其核苷酸多样性分别为3.25 × 10?3和0.94 × 10?3，单倍型多样性分别为0.883和0.242；两群体间存在显著的遗传分化，分化程度较高，其F_ST值达到0.148。单倍型网络分析结果显示:来自樱桃和毛桃的群体分别含有3种和9种单倍型，其中共有单倍型2种；不同单倍型在进化过程中主要发生了两个途径的进化，其中一个途径只出现了来自毛桃群体的1种单倍型，其他单倍型经过不同的突变步骤形成另一个途径。寄主特异性检验结果发现，来自樱桃的菌株具有一定的寄主特异性，而来自毛桃的菌株与寄主的关联性较差。综合研究表明，M. fructicola对多菌灵的抗性频率较高，且来自不同寄主的群体遗传结构差异性较大。     

四川省不同地域的核盘菌遗传多样性分析

 核盘菌(Sclerotinia sclerotiorum)属于世界性分布的植物病原真菌,可以危害油菜等多种经济作物。研究不同地域核盘菌的遗传多样性对了解核盘菌的遗传演化过程和指导病害防控具有重要意义。实验采用序列相关扩增多态性(sequence-related amplified polymorphism,SRAP)标记对四川省17个不同地理来源的66株核盘菌菌株的遗传多样性进行了分析。10对检测引物共获得129个位点,其中123个为多态位点,占95.35%。UPGMA聚类结果显示,在相似性系数为0.7时,66个核盘菌菌株分为5类(Ⅰ、Ⅱ、Ⅲ、Ⅳ、Ⅴ),分别包含60、2、2、1和1个菌株。在相似性系数为0.74时,第Ⅰ类又可分为3个亚类(Ⅰ-1、Ⅰ-2、Ⅰ-3),分别包含21、37和2个菌株。聚类及组成分分析结果显示,四川省各地区的核盘菌菌株具有较高的遗传多样性,但其遗传变异与菌株地理来源无明显相关性。     

四川省不同来源核盘菌菌株的可溶性蛋白和酯酶同工酶的电泳图谱分析

选取四川省不同地区、不同寄主、代表不同致病性水平和不同菌丝体亲和性表现的核盘菌(Sclerotinia sclerotiorum)菌株进行可溶性蛋白和酯酶同工酶电泳分析,结果表明:不同寄主来源、不同致病性水平、不同菌丝体亲和性表现的核盘菌菌株间的可溶性蛋白和酯酶同工酶电泳图谱条带数量及分布相对稳定,仅部份弱带在出现频率、染色强度或迁移距离上有一定的变化,表现出种的特征和种内的异质性,在分类上具有一定的意义,可溶性蛋白和酯酶同工酶电泳分析可作为核盘菌分类和遗传多样性分析的一个生化指标。     

绿僵菌菌株遗传多态性与地理来源及寄主种群分化的关联性

采用RAPD-PCR分子标记技术分析了51株不同地理来源、寄主来源的绿僵菌Metarhizium anisopliae菌株的遗传多态性。从94条RAPD引物中筛选出18条引物,对所有试验菌株进行RAPD-PCR扩增,共获得96条扩增片段,其中81条片段表现多态性,占84.1%。聚类分析表明,供试的51株菌株间的相似性系数范围为0.52~0.98,表明菌株间存在丰富的遗传多态性。供试菌株在相似性系数0.7的水平可分为4个组群。按菌株DNA多态性与地理及寄主来源的聚类分析表明,大多数菌株的DNA多态性与地理或寄主有一定的相关性,即长期的地理环境和寄主适应性可能形成了种群的分化。     

核盘菌对油菜、向日葵和大豆的侵染及其致病性分化研究

 通过对从陕西大荔采集的油菜及其后茬向日葵上的核盘菌和从新疆阿勒泰的向日葵上采集的核盘菌样品进行单菌核分离、培养和纯化,比较其菌丝生长速度、菌丝干重、菌落形态、致病力强弱及菌株的草酸累积等,将两地的核盘菌分成A、B、C三种类型,其中A类来源于陕西大荔的油菜和向日葵,B、C类来源于新疆阿勒泰的向日葵。不同类型核盘菌对于不同寄主的致病力存在着分化现象,A、B类菌株生长正常、菌落均匀旺盛,B类对油菜、向日葵和大豆的致病力较强,草酸产量较高;而A类仅对油菜和向日葵的致病力较强对大豆的致病力很弱,但草酸产量最高。C类菌株生长异常,菌落稀疏不均匀,对3种作物的致病力均弱,草酸产量较低。2001年田问调查亦表明:A类菌株可导致油菜、向日葵菌核病的发生,但未见其使大豆致病,由此提出油菜茬后,不宜种植向日葵,二者应与小麦、玉米等实行较长周期的轮作。本文也同时对各菌株进行了RAPD分析和菌丝体亲和性研究,结果表明,菌株间的遗传多样性表现丰富但未发现与其致病性分化相关。     

四川省不同寄主立枯丝核菌的遗传分化和致病力研究

 在四川省生态条件下,从不同水稻和玉米植株上分别分离到来源不同的立枯丝核致病菌15株和7株。致病力、菌丝融合实验结果表明,菌株均属于AG-11A群,各菌株间致病力差异显著。对分离菌株进行RAPD分析,结果显示,相似系数为0.92处菌株可聚合为5类,聚类分组和寄主来源有一定的相关性,来自相同寄主菌株的亲缘关系较近,不同寄主对立枯丝核菌的遗传分化有一定的影响,与病原菌的致病力差异没有直接的相关性。     

我国花绒寄甲不同寄主种群的遗传分化

寄生不同天牛种的花绒寄甲Dastarcus helophoroides Fairmaire经鉴定虽为同一种，但却表现出对其自身寄主的嗜好性，而对其他寄主趋性很弱。为明确其是否已分化为不同寄主种群，本文利用线粒体COI与ND5基因片段研究我国花绒寄甲6种寄主种群间的遗传分化。mtDNA-COI基因片段的分子变异分析结果显示，相同寄主种群内变异占总变异的75.64%，明显高于不同寄主种群间变异，Fst值为0.24358，相同寄主种群内个体间存在明显地遗传分化。最大相似法系统发育分析结果与6种不同寄主种群不符；mtDNA-ND5基因片段的分子变异分析结果显示，相同寄主种群内部变异占总变异的88.14%，明显高于不同寄主种群间变异，Fst值为0.11861，种群内个体间存在明显地遗传分化。ML树聚类结果与6种不同寄主种群不相符。     

Genetic Diversity and Structure of the Apiosporina morbosa Populations on Prunus spp

ABSTRACT Populations of Apiosporina morbosa collected from 15 geographic locations in Canada and the United States and three host species, Prunus virginiana, P. pensylvanica, and P. padus, were evaluated using the sequence-related amplified polymorphism (SRAP) technique to determine their genetic diversity and population differentiation. Extensive diversity was detected in the A. morbosa populations, including 134 isolates from Canada and the United States, regardless of the origin of the population. The number of polymorphic loci varied from 6.9 to 82.8% in the geographic populations, and from 41.4 to 79.3% in the populations from four host genotypes based on 58 polymorphic fragments. In all, 44 to 100% of isolates in the geographic populations and 43.6 to 76.2% in populations from four host genotypes represented unique genotypes. Values of heterozygosity (H) varied from 2.8 to 28.3% in the geographic populations and 10.2 to 26.1% in the populations from four host genotypes. In general, the A. morbosa populations sampled from wild chokecherry showed a higher genetic diversity than those populations collected from other host species, whereas the populations isolated from cultivated chokecherry, P. virginiana 'Shubert Select', showed a reduction of genetic diversity compared with populations from wild P. virginiana. Significant population differentiation was found among both the geographic populations (P < 0.05) and populations from different host genotypes (P < 0.02). In the geographic populations, most of populations from cultivated and wild P. virginiana were closely clustered, and no population differentiation was detected except for the populations from Morris, Morden, and Winnipeg, Manitoba, Canada. Furthermore, the populations from P. virginiana in the same geographic locations had higher genetic identity and closer genetic distance to each other compared with those from different locations. Four populations from P. virginiana, P. pensylvanica, and P. padus, were significantly differentiated from each other (P < 0.02), except there was no differentiation between the Shubert Select and wild chokecherry populations (>P> = 0.334). Indirect estimation of gene flow showed that significant restricted gene flow existed between populations from different regions and host species. Gene flow rates (Nm) varied from <1 to 12.5, with higher gene flow rates among population pairs from the same host species (P = 1.000). The analysis of molecular variance revealed that a major genetic variance source came from the genetic variation among isolates within populations regardless of the origin and host genotype of the population. Although some locations had a limited number of isolates, the results of this study clearly showed that the genetic diversity and population differentiation of A. morbosa were closely associated with host genotypes and geographic locations, but mostly with the former.     

油菜菌核病抗性鉴定方法的比较及抗源的筛选

采用已报道的七种油菜菌核病抗性鉴定方法,在同一条件下对两个感病和两个抗病品种进行鉴定比较。结果表明:草酸浸根(叶)法用于白菜型油菜鉴定效果不好;不同生育期的油菜对菌核病抗性有差异,应该以花期鉴定为主,苗期鉴定为辅;在花期以麦粒叶腋接种、琼脂块叶腋接种和牙签茎杆接种,接种后发病程度依次为牙签>麦粒>琼脂块;三种花期接种方法与大田接种鉴定的结果呈显著正相关(r>0.8000),这三种方法均能有效反映抗、感品种的差异,其中花期牙签茎杆接种法与大田接种鉴定法相关性达极显著水平(r=0.9140)。根据抗性鉴定方法比较的结果,选用花期牙签茎杆接种法,以中油821为对照,对四川农业大学油菜研究中心G1自交系的44份油菜育种材料进行鉴定、筛选,得到12份高抗材料,其中有5份材料的抗性极显著高于对照。     

枯草芽胞杆菌NJ-18对油菜菌核病的防治效果及其定殖动态

 菌株NJ-18是从油菜田土壤中分离筛选到的一株具有抗真菌活性的枯草芽胞杆菌。试验结果表明菌株NJ-18与油菜菌核病菌对峙培养能形成3.4 cm的抑菌圈;能抑制油菜菌核病菌菌丝生长发育;强烈影响菌丝生长量,NJ-18发酵滤液稀释62.5倍时对菌丝生长量抑制率高达96.7 %,稀释1 000倍时抑制率16.7 %。油菜离体叶片试验表明,NJ-18发酵液原液对菌核病的防治效果高达100 %,原液稀释200倍后防效10 %。大田试验结果表明,NJ-18发酵液稀释500倍对油菜菌核病的防治效果高达57.4 %,明显高于用量为150 g a.i./hm²的醚菌酯48.1 %的防治效果。采用浸根法研究NJ-18在油菜上的定殖动态表明,菌株NJ-18能够在油菜体内定殖,并能从油菜的根部向叶子扩散。     

Geographical Genetic Structure of Xylella fastidiosa from Citrus in São Paulo State, Brazil

ABSTRACT A total of 360 Xylella fastidiosa strains were isolated from sweet orange (Citrus sinensis) cv. Pera plants growing in five geographic regions in the Brazilian state of S?o Paulo. The genetic variation of these strains was determined by 15 variable number tandem repeat (VNTR) and 58 random amplified polymorphic DNA (RAPD) markers. The mean values of genetic diversity (H) of X. fastidiosa strains within each geographic region determined by RAPD (H(RAPD)) were substantially lower than H(VNTR) values. H(RAPD) values ranged from 0.00 to 0.095, whereas the H(VNTR) values ranged from 0.024 to 0.285. A highly significant value of Nei's coefficient of gene differentiation (G(ST) = 0.355; P = 0.000) was detected among all five populations. Analysis of the molecular variance (AMOVA) also revealed significant genetic differentiation among regions or populations ( phi(STAT) = 0.810; P< 0.001). In addition, genetic differentiation among subpopulations (plants) within the regions (phi(STAT) = 0.699; P < 0.001) and within each plant (phi(STAT) = 368; P < 0.001) were statistically significant. These high values of genetic differentiation among X. fastidiosa strains from different regions suggest a genetic structure according to region of host origin. However, no apparent correlation between genetic distance and region of origin of populations were supported statistically by Mantel analysis (r = 0.27; P = 0.22).     

Competence of <Emphasis Type="Italic">Xanthomonas campestris</Emphasis> from Cruciferous Weeds and Wallflower (<Emphasis Type="Italic">Erysimum cheiri</Emphasis>) to Induce Black Rot in Cabbage

Aphanomyces euteiches Drechsler is an oomycete pathogen of leguminous crops that causes root rot, a severe disease of pea (Pisum sativum L.) worldwide. An improved understanding of the genetic structure of A. euteiches populations would increase knowledge of pathogen evolution and assist in the design of strategies to develop pea cultivars and germplasm with stable disease resistance. Twenty six primers pairs were used to amplify Sequence Related Amplified Polymorphisms (SRAP) among 49 A. euteiches isolates sampled from pea. A total of 190 polymorphic SRAP bands were generated, of which 82 were polymorphic between all the A. euteiches isolates. The percentage of polymorphic bands per primer pair ranged from 22 to 75%. According to the PIC value estimated for each marker, 60% of the SRAP markers were highly to reasonably informative (PIC > 0.25). Genetic structure of A. euteiches populations sampled in different American and French locations showed low to high genetic diversity within populations. The largest variation occurred within countries, with a total estimated genetic diversity of 0.477 and 0.172 for American and French populations, respectively. This was particularly evident from a principal component analysis (PCA) and a Minimum Spanning Networks (MSN) based on genetic profiles of isolates, which generated two different clusters, one corresponding to the French isolates and four American isolates (MV1, MV5, MV7, Ath3), and the other to American isolates. A. euteiches populations from cultivated pea in France appeared as a single unstructured population, whereas American isolates of A. euteiches diverged into three different populations.     

Genetic Variability of Canadian Populations of the Sapstain Fungus Ophiostoma piceae

ABSTRACT Genetic diversity was studied in seven Canadian populations of Ophiostoma piceae, the most prevalent sapstain fungus in Canadian softwoods. A total of 239 single-spore isolates were recovered following a systematic survey of sapstain fungi in logs and lumber at seven selected sawmills in six Canadian provinces (British Columbia, Alberta, Saskatchewan, Ontario, Québec, and New Brunswick). Sampling was carried out on five commercially important softwood species: balsam fir (Abies balsamea), white spruce (Picea glauca), black spruce (Picea mariana), jack pine (Pinus banksiana), and lodgepole pine (Pinus con-torta var. latifolia). The A and B mating types occurred at equal frequency (MAT A/ MAT B = 1.00:1.13) over all populations. Pseudo-allelic frequencies were estimated at each of 24 putative genetic loci by scoring for presence or absence of random amplified polymorphic DNA fragments generated by five primers. A total of 237 haplotypes were found among the 239 isolates, revealing a high level of genotypic diversity among isolates. Total gene diversity (H(T) = 0.414) was mostly attributable to diversity within populations (H(S) = 0.369). Thus, only 11.2% of the total variability was attributable to frequency differences among populations. An analysis of molecular variance revealed that most genetic variability occurred within subpopulations within mills (84.3%; P < 0.001), whereas low but statistically significant levels of genetic differentiation were also observed among subpopulations within populations (5.4%; P < 0.001) and among populations (10.3%; P < 0.001). Estimates of Nei' genetic distances were not correlated with geographic distances among sampling locations (r = -0.092; P = 0.310), although principal component analysis indicated that subpopulations located east of Saskatchewan were grouped on the same side of the second principal component axis. Overall, results suggest moderate genetic differentiation of O. piceae in Canada, which is consistent with the observation that sexual reproduction is frequently observed in this fungus.     

Extent and pattern of genetic differentiation within and between European populations of Phelipanche ramosa revealed by amplified fragment length polymorphism analysis

The extent and pattern of genetic differentiation between Phelipanche ramosa populations colonising tobacco in different European regions were investigated by amplified fragment length polymorphism (AFLP) analysis, in order to determine levels of variation for tobacco resistance breeding and management programmes. Four different AFLP primer pairs amplified a total of 1050 clear and reproducible bands, of which 962 (91.62%) were polymorphic among the 35 individuals taken from four P. ramosa populations collected in Spain, Italy, Bulgaria and Germany. Cluster analysis based on the AFLP data categorised the plants into distinct groups, in line with their geographical origin, denoting clear genetic differentiation among the four populations. This differentiation was supported by both high bootstrap values and significant results of the analysis of molecular variance. The most divergent population was the one from Bulgaria. The majority of the genetic diversity was attributable to differences among populations (77.80%), as expected from the predominant autogamous behaviour of this species. Populations differed significantly in within-population diversity, as measured by Shannon's information index. The German population presented the lowest genetic diversity and the Italian population harboured the highest level of within-population genetic diversity. There are significant differences in genetic diversity level among the studied P. ramosa populations and clear population-specific genetic diversity structures. These need to be taken into account, together with the potential differences in parasite aggressiveness, when planning breeding and management strategies for P. ramosa control in tobacco cultivation.     

基于全基因序列的中国北方3省(区)马铃薯Y病毒遗传多样性分析

本研究以马铃薯Y病毒(PVY)全基因组为基础,分析吉林、黑龙江和内蒙古3省(区)PVY群体遗传多样性和群体分化,并评估突变、重组、选择等遗传力所起的作用。根据已报道的PVY全基因序列保守区设计4对引物,采用片段重叠法对来自内蒙古和吉林的24个PVY分离物全基因序列进行测定,并联合NCBI中已登录的9个黑龙江分离物全基因组序列进行遗传多样性参数评估、群体分化检验和分子变异等分析。结果显示,我国北方3省(区)PVY群体遗传多样性高,其中内蒙古和黑龙江PVY群体遗传多样性高于吉林群体,并且3个群体之间呈现一定程度的遗传分化。分子变异分析发现在PVY基因组中存在1 786个变异位点,表明我国北方3省(区)PVY群体变异程度较高,并且这种高变异度有85.54%来自各个马铃薯种植区内PVY个体的遗传变异。重组分析和系统发育分析发现,我国北方3省(区)PVY群体中重组株系占比高达90.3%,并具有明显的株系多样性,表明PVY重组株系已成为我国北方3省(区)马铃薯种植区的流行株系。选择压力分析显示,使用FEL和IFEL法分别检测出501个和315个净化压力选择位点,这表明3省(区)PVY群体受净化选择压力为主。以上结果表明,中国北方3省(区)PVY群体遗传多样性高,突变、重组和自然选择都对遗传多样性和群体分化存在一定影响。