猕猴桃溃疡病菌在中国的适生性分析

通过分析猕猴桃溃疡病菌在中国的适生性,为科学制定有效的检疫监管措施,防范其入侵和扩散,确保猕猴桃产业健康发展提供理论依据。本研究根据前人研究结果,采用模糊数学综合评判的原理和方法,定量分析猕猴桃细菌性溃疡病菌(Pseudomonas syringae pv.actinidiae)在我国各个地区的适生性。猕猴桃溃疡病菌在我国最适宜的省份主要分布在四川、云南、贵州、福建、安徽、湖南、湖北、河南、江西、陕西、浙江、重庆、西藏。鉴于该病具有发生发展迅速,危害性强,防治难度大等特点,应当加强猕猴桃种苗等繁殖材料的检疫,加强对果园的管理和病害监测,积极采取有效的防治措施并加强抗病育种方面的研究。     

GFPuv标记猕猴桃溃疡病菌的生物学特性 及其在土壤、根系中的定殖

【目的】获得具有荧光标记的猕猴桃溃疡病菌（Pseudomonas syringae pv. actinidiae）菌株,为进一步揭示其侵染致病过程奠定基础。【方法】电击法对病菌进行GFPuv基因标记,应用荧光显微镜和平板稀释法研究标记菌株在土壤和根部的定殖情况。【结果】GFPuv标记的猕猴桃溃疡病菌菌株在荧光显微镜下发出强烈的绿色荧光,8株标记菌基因组DNA中均扩增出约700 bp的目的片段。标记菌株PSAmx7-GFPuv1的菌体形态、生长曲线、最适温度、最适pH、致病性均与野生型无显著差异,其绿色荧光可稳定遗传。标记菌在灭菌土壤中可存活3个月左右,在未灭菌土壤中也能存活3周;灌根1 d检测,根表、根内组织中可分离到目标菌落,随后标记菌株数量呈现“先增后降”的趋势。【结论】电击法成功地将GFPuv基因转入猕猴桃溃疡病菌;导入的GFPuv 基因对宿主菌的生物学特性没有影响;标记菌可在灭菌土壤中长期存活,并在根部定殖和增殖。     

云南烟草野火病菌遗传多样性分析

应用Rep-PCR分子指纹技术结合传统植物病理学分析了51个采自云南各大烟区的烟草野火病菌（Pseudomonas syringae pv.tabaci)以及其他不同致病变种、不同种、不同属的植物病原菌的群体遗传多样性。用REP、ERIC,BOX,IS1112和IS1113等5组专化性的引物对以上菌系基因组DNA进行PCR扩增,并对扩增指纹图谱综合进行UPGMA聚类分析,在相似水平0．92时,可将云南烟草野火病菌分为3个群,即YN1,YN2,YN3。     

Identifying resistance in wild and ornamental cherry towards bacterial canker caused by Pseudomonas syringae

Bacterial canker is a major disease of stone fruits and is a critical limiting factor to sweet cherry (Prunus avium) production worldwide. One important strategy for disease control is the development of resistant varieties. Partial varietal resistance in sweet cherry is discernible using shoot or whole tree inoculations; however, these quantitative differences in resistance are not evident in detached leaf assays. To identify novel sources of resistance to canker, we used a rapid leaf pathogenicity test to screen a range of wild cherry, ornamental Prunus species and sweet cherry × ornamental cherry hybrids with the canker pathogens, Pseudomonas syringae pvs syringae, morsprunorum races 1 and 2, and avii. Several Prunus accessions exhibited limited symptom development following inoculation with each of the pathogens, and this resistance extended to 16 P. syringae strains pathogenic on sweet cherry and plum. Resistance was associated with reduced bacterial multiplication after inoculation, a phenotype similar to that of commercial sweet cherry towards nonhost strains of P. syringae. Progeny resulting from a cross of a resistant ornamental species Prunus incisa with susceptible sweet cherry (P. avium) exhibited resistance indicating it is an inherited trait. Identification of accessions with resistance to the major bacterial canker pathogens is the first step towards characterizing the underlying genetic mechanisms of resistance and introducing these traits into commercial germplasm.     

1株高冰核活性细菌的分离与鉴定

从发生冻害的植物组织中分离到1株冰核细菌MB03,该菌株在-3℃时在2 min内的冻结率达到96.5%,而产生1个冰核所需要的细胞数约为2.9×103个,其冰核活性明显高于冰核细菌标准菌株和其它分离菌株.进一步对MB03进行了鉴定,经个体形态与培养特征观测、部分生理生化反应、G C摩尔分数测定、16SrDNA序列对比分析、菌落原位杂交探测特异性基因和PCR扩增冰核基因等鉴定,确定该菌为丁香假单胞菌(P5eudomonas syringae).     

Susceptibility of Iberian trees to Phytophthora ramorum and P. cinnamomi

The capacity of Phytophthora ramorum to colonize the inner bark of 18 native and two exotic tree species from the Iberian Peninsula was tested. Living logs were wound-inoculated in a growth chamber with three isolates belonging to the EU1 and two to the NA1 clonal lineages of P. ramorum . Most of the Quercus species ranked as highly susceptible in experiments carried out in summer, with mean lesion areas over 100 cm² in Q. pubescens , Q. pyrenaica , Q. faginea and Q. suber and as large as 273 cm² in Q. canariensis , ca . 40 days after inoculation. Quercus ilex ranked as moderately susceptible to P. ramorum , forming lesions up to 133 cm² (average 17·2 cm²). Pinus halepensis and P. pinea were highly susceptible, exhibiting long, narrow lesions; but three other pine species, P. pinaster , P. nigra and P. sylvestris , were resistant to slightly susceptible. No significant difference in aggressiveness was found between the isolates of P. ramorum . In addition, there was evidence of genetic variation in susceptibility within host populations, and of significant seasonal variation in host susceptibility in some Quercus species. The results suggest a high risk of some Iberian oaks to P. ramorum , especially in forest ecosystems in southwestern Spain, where relict populations of Q. canariensis grow amongst susceptible understory species such as Rhododendron ponticum and Viburnum tinus . One isolate of P. cinnamomi used as positive control in all the inoculations was also highly aggressive to Iberian oaks and Eucalyptus dalrympleana .     

Infection of horse chestnut (Aesculus hippocastanum) by Pseudomonas syringae pv. aesculi and its detection by quantitative real-time PCR

Pseudomonas syringae pv. aesculi is a pathogenic bacterium causing bleeding canker disease of horse chestnut ( Aesculus hippocastanum ). This is a serious disease which has been affecting horse chestnut in several European countries over the last five years; however, very little is known about the biology of the causal agent. One of the obstacles to studying this pathogen is the lengthy procedure associated with confirming its presence on the host. In this study, P. syringae pv. aesculi was isolated from lesions on different parts of horse chestnut and its pathogenicity confirmed on horse chestnut saplings using two inoculation techniques. Real-time PCR primers were developed based on gyrase B gene sequence data for the specific detection of P. syringae pv. aesculi . Primer specificity was tested on isolates of the target pathogen as well as on a broad range of related non-target bacteria and other bacterial spp. which inhabit horse chestnut. The real-time primers reliably amplified P. syringae pv. aesculi down to 1 pg of extracted DNA, with and without the presence of host DNA, and also amplified unextracted DNA in whole cells of the bacterium down to at least 160 colony forming units. Detection and quantification of the target pathogen in phloem and xylem of both naturally infected and inoculated horse chestnut tissues was also demonstrated. This quantitative real-time PCR assay provides the facility to study several important aspects of the biology of P. syringae pv. aesculi on horse chestnut including its potential for dissemination in different substrates.     

Activation of systemic disease resistance in pea by an avirulent bacterium or a benzothiadiazole, but not by a fungal leaf spot pathogen

Inoculation of first expanded leaves of pea seedlings with an avirulent strain of Pseudomonas syringae pv. pisi , or treatment with sprays of a benzothiadiazole (20 or 100  μ g a.i. mL⁻¹), decreased the susceptibility of subsequent leaves 7 or 14 days later to challenge inoculation with Mycosphaerella pinodes . Inoculation of first leaves with a virulent strain of P. syringae pv. pisi or with M. pinodes did not decrease the susceptibility of plants to M. pinodes . Treatments effective in decreasing susceptibility to M. pinodes were similarly active against Uromyces viciae-fabae and virulent P. syringae pv. pisi . Effective treatments also enhanced the activities of the enzymes β-1,3-glucanase and chitinase in untreated upper leaves 6 days later. Ineffective treatments for decreased susceptibility had no effect on the activity of the enzymes. None of the treatments enhanced peroxidase activities. The results are discussed in relation to the reported signalling effects of the benzothiadiazole and in relation to a suggested high activity of the avirulent P. syringae pv. pisi strain and inactivity of M. pinodes in enhancing natural signalling.     

黄瓜细菌性茎枯萎病病原鉴定及温度对其致病力的影响

自2003年以来, 在我国北京?辽宁和山东等地的黄瓜上发现了一种重要细菌病害—黄瓜细菌性茎枯萎病, 对黄瓜生产造成了严重危害?从发病的黄瓜叶片?茎部和果实上分离的菌株接种到黄瓜后, 症状与自然发病症状完全一致?经过多位点序列分型和BOX-PCR技术, 以及LOPAT?GATTa和Ayers碳源利用试验等, 确定该病害的病原菌为丁香假单胞流泪致病变种 Pseudomonas syringae pv. lachrymans?以黄瓜细菌性茎枯萎病菌A2为供试菌株, 黄瓜细菌性角斑病菌丁香假单胞菌流泪致病变种 P.syringae pv. lachrymans pslb8为对照菌株, 对其进行不同温度下致病力?体内和体外生长能力测定, 结果表明:20℃条件下, A2菌株的致病力?体内和体外生长能力均强于pslb8菌株, 相对低温的条件更有利于黄瓜细菌性茎枯萎病病原菌的侵染和病害的发生?     

黄瓜细菌性角斑病菌交叉引物恒温扩增检测技术

黄瓜细菌性角斑病是我国黄瓜生产上的重要病害之一,其病原菌为Pseudomonas syringae pv.lachrymans。根据该病原菌甘油醛-3-磷酸脱氢基因保守序列设计引物和探针,建立了交叉引物恒温扩增和核酸试纸条检测技术。菌体DNA检测灵敏度可达0.55 ng,纯菌直接检测灵敏度基本可达到单个细菌。所测试的5株黄瓜细菌性角斑病菌和染病黄瓜叶片均为阳性,其他13株对照菌株均为阴性。该方法灵敏度高,且操作简单,对设备要求低等,适合基层实验室应用。