广西十字花科黑腐病菌致病性分化及遗传多样性分析

为了研究广西十字花科黑腐病菌(Xanthomonas campestris pv.campestris,XCC)的致病性差异和遗传多样性。本研究采用剪叶接种法对来自广西十字花科物种的24个菌株进行致病性分析,并利用细菌基因组的重复序列PCR(Rep-PCR)技术,对供试菌株的遗传多样性进行研究。结果表明:采用剪叶接种方法,供试菌株致病力均可划分为5种致病型,且与菌株的地理来源有一定的相关性;利用细菌基因组重复序列通用引物进行Rep-PCR扩增,在遗传距离为0.79时,供试菌株可被划分为5个遗传相似组,与染病作物无明显的关联性,而与同一地区的关系有相对明显的关联性,并由此得到这样的结论:侵染广西十字花科黑腐病菌存在明显的致病性分化和丰富的遗传多样性。     

橡胶炭疽病病原菌生物学特性初步研究

测试了7个来自云南省版纳地区的橡胶树炭疽病菌的菌株在不同培养基、温度及pH条件下的生长速率,观察了这些菌株在PDA上的菌落和分生孢子形态,测定了这些菌株的致病力。发现这些菌株的最适生长的培养基、温度、pH和对橡胶树的致病力存在明显的差异,对橡胶树的致病力有明显不同,菌落和分生孢子形态也存在可观察到的差异。     

辽宁省辣椒疫病菌多态性及致病力分化研究初探

【目的】明确辽宁省辣椒疫病菌多态性及致病力分化与区域性关系。【方法】利用SRAP技术对辽宁省25个辣椒疫病菌菌株进行了PCR扩增及NTSYS-PC聚类分析,用灌根法进行致病力分化试验并对试验结果进行SPSS 11.5分层聚类分析。【结果】利用筛选出的27组引物对25个菌株进行扩增,得到578条条带,每对引物多态性比率在84%?100%之间,多态性丰富;供试菌株间遗传相似性较高,相似系数0.56?0.91,以相似系数0.68为阈值划分,25个菌株可聚为4组。试验菌株80%为中等致病力,聚类结果较为分散。【结论】供试菌株没有表现出明显的区域性特征,菌株致病力强弱分化区域特征性规律不明显。     

不同寄主来源的灰葡萄孢对番茄的致病力分化研究

从安徽合肥、蚌埠、长丰、和县等市、县的番茄、辣椒、草莓、葡萄等发病寄主上分离鉴定获得18个灰葡萄孢Botrytis cinerea菌株,采用菌丝块创伤接种法,分别测定了上述不同寄主来源的灰葡萄孢菌对番茄果实和叶片的致病力.结果表明,所有供试菌株接种番茄果实后均引起发病,但不同菌株所致病斑的平均直径有显著差异,显示灰葡萄孢菌株间对番茄果实的致病力存在明显分化.按照在番茄果实上所致病斑的平均直径大小可将供试菌株致病力划分为较强、中等和较弱3种类型.总体来说,来自番茄的菌株对番茄果实的致病力较强,来自草莓、葡萄和辣椒的菌株对番茄果实的致病力较弱,但来自相同寄主的菌株间致病力也存在差异,菌株致病力差异与菌株地域来源无明显相关.供试灰葡萄孢菌株接种番茄叶片后,除CF1外,均可引起番茄叶片发病,但不同菌株所致番茄叶片病斑的平均直径也有显著差异;供试菌株对番茄叶片的致病力差异与菌株的寄主和地域来源无显著相关.     

广东省水稻纹枯病菌遗传多样性与致病力分化的研究

利用随机引物扩增多态性DNA（PAPD）分子标记技术分析了来自广东省7个县市48个水稻纹枯病菌菌株的遗传多样性,以筛选出的10个随机引物对菌株进行PAPD－PCR扩增,共产生了98个PAPD分子标记,其中89．9％的片段具有多态性。48菌株间的遗传相似性系数（以Nei基因一致度表示）在0．56－0．949之间,用UPGMA和类分析可将它们分为5个RAPD遗传聚类群（A、B、C、D、E）,相同地区来源的菌株基本上聚类在同一组群内。在温室中对供试菌株进行致病性测定,结果表明所有菌株对水稻品种Tetep都有致病性,菌株间致病力差异显著（α＝0．05）,病情指数范围为0．73－18．7,平均感指病指数为5．24。试验分析结果表明水稻纹枯病菌具有丰富的遗传多样性,不同县市的菌株存在很大的遗传分化现象（FST＝0．579）,RAPD遗传聚类群的划分与菌株的地理来源有明显的相关性,但菌株的致病力差异与菌株的来源、遗传聚类组群的划分没有明显的相关性。     

新疆石河子地区棉花黄萎病菌分离鉴定及其致病力分析

旨在探究新疆石河子地区棉花黄萎病菌遗传变异及致病力分化情况。通过对分离菌株显微观察、ITS序列克隆及分子进化树的构建,对来源不同的棉花黄萎病菌分离鉴定以及致病力进行分析研究。结果表明:分离得到的24株棉花黄萎菌均属大丽轮枝菌(Verticillium dahliae),其中11株菌株为落叶型棉花黄萎菌,其余为非落叶型棉花黄萎菌;分子进化树结果显示24株菌在系统进化方式上属于2个不同的分支;相同寄主的致病力结果显示24株菌的致病力分为强中弱3个类型,其中强致病力比例为75%,相比2010年的51.7%提高了23.3%,表明石河子地区棉花黄萎菌群体致病力类型发生较大变化,强致病力菌系的比例增加,这或许与石河子地区常年种植棉花有一定的关系;其中SHZ-9为致病力最强的菌系,而SHZ-4为致病力最弱菌系,表明石河子地区黄萎菌存在着明显的致病力分化现象;不同致病力菌株按照营养亲和性可分为3个营养亲和群(VCGs)。本研究结果表明新疆石河子地区棉花黄萎病的致病菌基本是大丽轮枝菌,强致病力菌系占的比例在增加,且菌株在遗传分化上存在明显差异。     

华南瓜类疫霉的RAPD遗传多样性分析

为了解来自广东和广西的瓜类疫霉的遗传多样性,利用从180条RAPD引物中所筛选出的多态扩增性强、重复性好的12条引物,对分离自两省区的96株瓜类疫霉进行了全基因组DNA遗传多样性分析和指纹图谱构建。通过对供试菌株的RAPD-PCR扩增,共获得135条DNA标记谱带,其中124条为多态性谱带,多态检测率为91.9%。利用NTSYSpc Version2.1软件对供试菌株间的遗传距离进行聚类分析并构建系统树,以遗传相似系数0.81为阈值,将96个供试菌株划分为12个RAPD群,多数分离物之间遗传相似性较低,在DNA水平上存在显著的遗传变异,具有较丰富的遗传多样性。不同地区间菌株的遗传分化程度不同,分离自黄瓜的菌株遗传分化明显高于分离自冬瓜的菌株。RAPD群与菌株地理来源、分离寄主、致病力、交配型及甲霜灵抗性均无明显的相关性。     

小麦全蚀病菌致病力测定及品种抗病性研究

近年来,小麦全蚀病在我国黄淮麦区的发生呈上升趋势,为了解该病菌的致病力及目前推广品种的抗病性,本研究比较了全蚀病菌致病力的3种接种测定方法和2种病情分级标准,结果表明以蛭石为培养基质、麦种下2cm接种菌丝块和0～6级的分级标准,可比较有效和准确地测定小麦全蚀病菌的致病力。对2010年分离自黄淮麦区河南、江苏、安徽、山东4省10地的52株小麦全蚀病菌进行了致病力测定,结果表明供试菌株的致病力存在明显差异。选取致病性较强的菌株G1037,对69个常用小麦品种进行了苗期抗全蚀病鉴定,结果表明供试小麦品种对全蚀病的抗性水平普遍较低,没有发现免疫和高抗的品种,泛麦5号和太空6号具有较强的抗(耐)性。     

江西稻瘟病菌稻巨座壳致病性分化年度动态变化

为明确江西水稻种植区稻巨座壳菌（稻瘟病病菌）的年际变化规律,本研究采用7个中国鉴别寄主与30个单基因鉴别品系两套鉴别寄主分别鉴定分析了2006-2018年间从江西37个水稻主要种植县市分离的1 161个稻瘟病单孢菌的生理小种、致病力、致病类型与无毒基因型等。研究结果表明,江西稻瘟病菌可以分成7群49个生理小种,其中ZA、ZB、ZC群为优势种群,ZB13为优势小种,出现频率为18.00%,以毒性较强的强致病力菌株为主;江西稻瘟病菌在生理小种构成、优势小种、致病力年际变化方面均具有3-5年的周期性;江西历年稻瘟病菌的致病类型较为丰富且存在年度差异,菌株致病类型占各年度总菌株数的82.79%-98.21%,优势致病型菌株占当年总菌株的3.57%-5.77%;历年稻瘟病菌的无毒基因个数为24-29个,其中Avr-Pizt、Avr-Piz5、Avr-Pik、Avr-Pik(C)在历年供试菌株中出现频率较高,说明与之相对应的抗瘟基因在江西抗病育种与抗性品种布局中具有较好的应用价值。     

十字花科黑腐病菌的XC1193基因与致病相关

十字花科黑腐病菌(Xanthomonas campestris pv.campestris,Xcc)是一种重要植物病原细菌,在全球范围内侵染十字花科植物引起黑腐病,其σ因子在基因表达中起到重要调节作用。XC1193基因在Xcc 8004菌株编码一个σ~70因子,为进一步研究该σ因子在Xcc中的调控作用,利用自杀质粒p K18mobsac B构建了XC1193基因的缺失突变体DM1193。与野生型菌株的比较发现,XC1193基因突变不影响菌体在丰富培养基和基本培养基上的生长;突变体的胞外蛋白酶、纤维素酶、淀粉酶等生化表型也与野生型一致;植株实验表明XC1193突变不影响过敏反应。采用剪叶接种法进行致病性检测,突变体致病力与野生型一致。而采用喷雾接种法,突变体致病力显著降低,互补菌株致病力恢复至野生型水平。结果表明,该σ因子在十字花科黑腐病菌致病过程中发挥作用,并与Xcc侵染寄主的早期事件有关。     

Nonhost resistance of barley is successfully manifested against Magnaporthe grisea and a closely related Pennisetum-infecting lineage but is overcome by Magnaporthe oryzae

Magnaporthe oryzae is a major pathogen of rice (Oryza sativa L.) but is also able to infect other grasses, including barley (Hordeum vulgare L.). Here, we report a study using Magnaporthe isolates collected from other host plant species to evaluate their capacity to infect barley. A nonhost type of resistance was detected in barley against isolates derived from genera Pennisetum (fontaingrass) or Digitaria (crabgrass), but no resistance occurred in response to isolates from rice, genus Eleusine (goosegrass), wheat (Triticum aestivum L.), or maize (Zea mays L.), respectively. Restriction of pathogen growth in the nonhost interaction was investigated microscopically and compared with compatible interactions. Real-time polymerase chain reaction was used to quantify fungal biomass in both types of interaction. The phylogenetic relationship among the Magnaporthe isolates used in this study was investigated by inferring gene trees for fragments of three genes, actin, calmodulin, and beta-tubulin. Based on phylogenetic analysis, we could distinguish different species that were strictly correlated with the ability of the isolates to infect barley. We demonstrated that investigating specific host interaction phenotypes for a range of pathogen isolates can accurately highlight genetic diversity within a pathogen population.     

THE LINE-PATTERN VIRUS DISEASE OF PLUMS

The disease, now usually called line-pattern of plum, has been described under many names in most countries where plums are grown extensively.
Naturally infected trees show widely differing Symptoms; this has two causes: (1) different varieties react differently to the same isolate of the virus, and (2) different isolates cause different symptoms in the same variety. Because the virus occurs in strains with different pathogenicities, the choice of indicator varieties is important when selecting virus-free material by transmission tests. Peach seedlings and the mazzard clone, F 12/1, were the most sensitive types found.
The line-pattern virus does not become fully systemic in some varieties of plum. In this and other respects, it resembles the viruses that cause apple mosaic; three isolates obtained from plum and two from apple produced similar Symptoms in peach and apple. It is therefore suggested that plum line-pattern and apple mosaic viruses are caused by strains of one virus.     

黑龙江省抗寒李资源花粉形态的比较观察

对31个寒地李资源进行了电镜扫描,在测量极轴、赤道轴,条脊宽、穿孔径、穿孔频率后,分析出31个李品种花粉粒大小属于小至中等,31个李品种大多为长球形（比值2～1.14）,个别品种牛心李、长李17号、吉林六号为超长球形（比值>2）, 均有3条沿极轴走向的等间距的发芽沟,发芽沟的有开张、半开张、不开张3种。31个李品种的外壁纹饰可以分为七种类型,大多数李品种的纹饰是条脊平行或分枝多穿孔纹饰,云状纹饰品种少为矮甜李、龙园秋李,脑纹状纹饰只有延吉李。根据极轴、赤道轴、条脊宽、穿孔径、穿孔频率5项指标,采用最远距离法对31个李品种进行聚类分析,牛心李与其它30个李品种亲缘较远。     

A comparison of Olpidium isolates from a range of host plants using internal transcribed spacer sequence analysis and host range studies

Olpidium brassicae is a ubiquitous obligate root-infecting fungal pathogen. It is an important vector of a wide range of plant viruses. Olpidium isolates that infected brassica plants did not infect lettuce plants and vice-versa. Host range tests, PCR amplification and sequencing of the internal transcribed spacer (ITS) and 5.8S regions of 25 Olpidium isolates from brassica, carrot, cucumber and lettuce originating from four continents revealed differences between isolates. Based on their ability to infect lettuce and brassicas and the differences between their ITS1, 5.8S and ITS2 regions they could be separated into a number of distinct groups. Comparisons with other published sequences revealed two distinct genetic groups of brassica-infecting isolates, two distinct groups of lettuce-infecting isolates, one of which contained a carrot-infecting isolate and a distinct group comprising a cucumber-infecting isolate and a melon-infecting isolate. The possibility of the isolates belonging to three distinct species is discussed.     

Studies on the Bacteriophagy of Pseudomonas mors-prunorum, Ps. syringae and Related Organisms

S ummary : A group of 23 phages, mainly isolated with Pseudomonas mors-prunorum and Ps. syringae as the propagating strains, was tested against more than 200 pseudomonads including named plant pathogens and a variety of saprophytes. The majority of the phages had a wide host range, and did not distinguish between plant pathogens and saprophytes, thus confirming the close relationship between these two groups. The most reactive bacteria were 60 English isolates of Ps. mors-prunorum , 48 from cherry and 12 from plum, and 28 isolates of Ps. syringae from pear. Patterns of reaction within these 3 groups were relatively homogeneous and each group was distinct and differed from all other isolates tested. Ps. syringae isolates from other hosts were less uniform and occasionally shared reaction patterns with other species, e.g. Ps. cannabina and Ps. glycinea. Similar relationships were observed with phages at both high titre and at routine test dilution including the difference in phage sensitivity between the cherry and plum strains of Ps. mors-prunorum. On the basis of 7 biochemical tests the plum and cherry strains were indistinguishable but they differed from all Ps. syringae isolates tested by giving white growth in 5% sucrose broth and in failing to liquefy gelatin. Furthermore, unlike most Ps. syringae isolates they were also unable to hydrolyze aesculin and were tyrosinase positive. There was no clear evidence in this investigation of correlation between phage sensitivity and biochemical activity. Eleven isolates from various European countries, designated Ps. mors-prunorum , differed widely both in phage sensitivity and biochemical activity and some of them may be more appropriately called Ps. syringae. Others may be intermediate forms between these species. The relationship between Ps. mors-prunorum and Ps. syringae and the nomenclature of these organisms are discussed and a concept of ecotypes suggested as a substitute for species.     

Diversity of Opines and Opine-Catabolizing Bacteria Isolated from Naturally Occurring Crown Gall Tumors

The diversity of opines from 43 naturally occurring crown gall tumors on several plant species was analyzed for the presence of agropine, chrysopine, iminodiacid, an unidentified leucinopine-like iminodiacid (IDA-B), mannopine, octopine, nopaline, DL- and LL-succinamopine, leucinopine and heliopine. Opine utilization patterns of agrobacteria and fluorescent pseudomonads resident in a tumor were then analyzed and compared for agreement with the opine isolated from that tumor. Nopaline was the most common opine found and was detected in tumors from cherry, blackberry, grape, and plum. Octopine was not found, although octopine-catabolizing bacteria were isolated from several tumors. A new, previously undescribed iminodiacid of the succinamopine-leucinopine type (provisionally designated IDA-B) was isolated from tumors of wild blackberry. Field tumors from apple, blueberry and grape yielded no detectable opines, even though opine-utilizing bacteria were present. Bacterial isolates from plum and cherry showed the best correspondence between the opine in tumors (nopaline) and the presence of bacteria that catabolized that opine. However, several unusual opine catabolic combinations were identified, including isolates that catabolized a variety of opines but were nonpathogenic. More variability was observed among isolates from field tumors on the remaining plant species. We isolated novel mannopine-nopaline type agrobacteria from field tumors of cherry, plum and blackberry that induced tumors containing either mannopine (plus agropine) or nopaline, but not both. Epidemiologically, the galled plants from an area were not of clonal origin (same Ti plasmid), indicating that the field tumors from a small area were incited by more than one type of Ti plasmid.     

DNA restriction patterns and DNA-DNA solution hybridization studies of Frankia isolates from Myrica pennsylvanica (bayberry).

Sixteen Frankia strains were isolated from Myrica pennsylvanica (bayberry) root nodules collected at diverse sites in New Jersey. Restriction pattern analysis of total genomic DNA was used to group the isolates into gel groups, and the genetic relatedness among the isolates was evaluated by DNA-DNA solution hybridization studies. Restriction pattern analysis provided a distinctive reproducible fingerprint for each isolate. Isolates fell into nine separate groups (strain types). More than one strain type was isolated from most sites. Isolates from two different gel groups were found in 3 of 10 nodules examined. Of the 16 isolates, 10 contained extrachromosomal DNA. Six different extrachromosomal DNA banding patterns were found. Genomically similar isolates carried related, but different, banding patterns. DNA hybridization studies indicated that isolates from a single plant species can be minimally related as determined by total genome homology. Homology ranged from 12 to 99%. Highly divergent strains were isolated from the same plant and found to cohabit the same nodule. Thus, this study demonstrated that Frankia strains which infect the same host plant are not only phenotypically different but also genetically diverse.     

DNA restriction patterns and DNA-DNA solution hybridization studies of Frankia isolates from Myrica pennsylvanica (bayberry)

Sixteen Frankia strains were isolated from Myrica pennsylvanica (bayberry) root nodules collected at diverse sites in New Jersey. Restriction pattern analysis of total genomic DNA was used to group the isolates into gel groups, and the genetic relatedness among the isolates was evaluated by DNA-DNA solution hybridization studies. Restriction pattern analysis provided a distinctive reproducible fingerprint for each isolate. Isolates fell into nine separate groups (strain types). More than one strain type was isolated from most sites. Isolates from two different gel groups were found in 3 of 10 nodules examined. Of the 16 isolates, 10 contained extrachromosomal DNA. Six different extrachromosomal DNA banding patterns were found. Genomically similar isolates carried related, but different, banding patterns. DNA hybridization studies indicated that isolates from a single plant species can be minimally related as determined by total genome homology. Homology ranged from 12 to 99%. Highly divergent strains were isolated from the same plant and found to cohabit the same nodule. Thus, this study demonstrated that Frankia strains which infect the same host plant are not only phenotypically different but also genetically diverse.     

Comparison of Some Isolates of Potato Leaf Roll Virus in Poland

18 PLRV isolates differed in severity of symptoms induced on Physalis floridana and on three potato cultivars (Osa, Pola, and Giewont). Reactions of potato cultivars to individual isolates were not always related. Some isolates induced more severe symptoms than others in all host plants. Isolates producing more severe symptoms reached a higher concentration in potato cultivars (evaluated with ELISA test) and were more virulent to Capsella bursa-pastoris. An interaction between PLRV isolates and host plants could be demonstrated. In general, the severity of the reaction of cv. Pola was related to that of P. floridana but not to the reaction of cvs. Osa and Giewont. The reactions of cvs. Osa and Giewont were closely related. All six isolates selected for a more detailed study could infect C. bursa-pastoris with obvious disease symptoms if potato cv. Osa served as source of the virus. Some isolates failed to infect this plant when other cultivars were used.