大豆疫霉菌的分离、鉴定及菌株致病力的测定

利用组织分离法,种子、植株诱集法和叶碟诱集法可分离到大豆疫霉菌。对分离到的菌株的致病力测定结果表明,大豆疫霉菌存在着明显的生理分化现象。     

Identification of sources of resistance to damping-off and early root/hypocotyl damage from Rhizoctonia solani in common bean (Phaseolus vulgaris L.)

Rhizoctonia solani causes economically important root and hypocotyl diseases in common bean throughout the world. Root health is a vital factor in plant development and root diseases would negatively influence water and nutrient uptake as well as cause direct stand reduction and root rot damage to the crop. An efficient common bean screening method to evaluate damping-off and early root/hypocotyl damage from R. solani was developed and used to identify dry bean lines with levels of resistance to this disease. Two sets of 163 and 111 lines previously evaluated for drought tolerance in Nebraska and Puerto Rico were evaluated for damping-off resistance and early root/hypocotyl damage under greenhouse conditions. Disease severity on plants was identified based on above-ground symptoms, seedling survival and root lesions using a rating scale of 1 (resistant) to 9 (susceptible). In the first set of lines representing commonly grown dry bean cultivars, germplasm and sources of damping-off resistance, the Rhizoctonia mean rating ranged from 1.7 to 3.9; Phaseolus vulgaris lines PI 310668 and PI 533249 had the highest damping-off resistance. In the second set of the best lines from a drought tolerance shuttle breeding program the Rhizoctonia mean rating was between 2.6 and 5.7. The availability of drought tolerant dry bean lines allowed the testing of the hypothesis that there was a correlation between selecting for drought tolerance and R. solani damping-off resistance. No correlation between mean disease rating and drought tolerance was found, but adapted dry bean lines such as NE14-08-176 released as SB-DT1, and NE14-08-225 were identified with moderate damping-off resistance and drought tolerance. Lines with both traits and other attributes will facilitate development of resistant bean cultivars to manage damping-off caused by R. solani.     

我国部分地区禽病原性大肠杆菌的分离与鉴定

从江苏、广东、河南、新疆、四川、北京、黑龙江等１８个省、市、自治区临 有典型大肠杆菌病病变的病禽１０５１羽采集病料,分离培养和鉴定出５９５株大肠杆菌。经Ｏ血清型测定,除１４４株未能定型、１１株自凝外,共出４４０个分离株的Ｏ血清型。这些 ５０个血清型,但以Ｏ１８、Ｏ７８、Ｏ２、Ｏ８８、Ｏ１１、Ｏ２６、Ｏ４、为、Ｏ１２７６、Ｏ１３１等１０个血清型为主,这些分离株覆盖了６０个血清型,但以血Ｏ１８、Ｏ７８     

广西大王岭和大明山自然保护区苏云金芽孢杆菌收集与鉴定

从广西大王岭和大明山两个自然保护区共采集到土样264份，共分离出597株芽孢杆菌，通过光学和电子显微镜检观察，16株分离株观察到伴胞晶体蛋白，初步确定为苏云金芽胞杆菌（Bacillus thuringiensis，简称Bt），出菌率为6．06％。在16株肪分离株中，有4株在芽孢形成过程中能产菱形晶体蛋白，其余12株能产圆形和其他形状的晶体蛋白。利用PCR—RFLP方法和SDS．PAGE方法对16株助分离菌进行了蛋白和基因型的鉴定，结果表明，16株分离株中含有4株crylAc基因，表达约130kD的晶体蛋白，其中含有cry30基因和cry40基因的菌株分别1株和3株，表达大约75kD的晶体蛋白；另外8株戤菌株表达蛋白大小不一，其基因型尚不能确定，有待进一步分析。生物测定表明，产菱形晶体含有crylAc基因的4株励分离株对鳞翅目小菜夜蛾幼虫有很强的毒杀活性，而其它分离株对小菜夜蛾没有毒杀活性。     

Characterization of immunogenic proteins of Trypanosoma evansi isolated from three different Indian hosts using hyperimmune sera and immune sera

The western blot analysis for identification of immunogenic proteins in whole cell lysate (WCL) antigens (Ags) prepared from the Trypanosoma evansi of buffalo, horse and cattle origins using hyperimmune sera (HIS) showed 11 immunogenic proteins and naturally T. evansi infected immune sera (IS) of horse detected 19 immunogenic proteins. HIS and IS of horse recognized five common immunogenic proteins of relative molecular weight (M(r)) ranges 61-64, 44-47, 33-34, 25-26 and 14-16 kilo Dalton (kDa). HIS rose against WCL Ags of T. evansi of buffalo origin and immune sera of horse cross reacted with WCL Ags of T. evansi of different host origin. It can be concluded that in comparison to HIS, IS of horse could able to detect more numbers of immunogenic proteins and five common immunogenic proteins in WCL Ages of T. evansi of different hosts origin. The evidence of higher reactivity of IS in comparison to HIS against T. evansi is being reported for the first time.     

一株鸭源巴氏杆菌的分离与药敏实验

对扬州邗江区某养殖户送检的4只病死高邮麻鸭进行剖检,取病死鸭肝脏进行细菌分离,在鲜血琼脂培养基上经过37℃培养24 h后,出现灰白色、湿润、边缘整齐、露珠状、不溶血的小菌落;在麦康凯培养基上不生长。病料触片经美蓝染色后镜检发现呈蓝紫色、两端着色深、中间着色浅的球杆菌;生化特性符合多杀性巴氏杆菌特性;药敏试验该菌对头孢曲松钠、复方新诺明、多粘菌素B等药物有较强的敏感性。     

Antimicrobial resistance pattern of Salmonella serotypes isolated from food items and personnel in Addis Ababa, Ethiopia

Antimicrobial susceptibility test of 98 isolates of Salmonella was assayed from September 2003 to February 2004 using the guidelines of the National Committee for Clinical Laboratory Standards (NCCLS).The result revealed that 32.7% of Salmonella isolates were resistant to one or more of the 24 antimicrobials tested. Generally resistance for 13 different antimicrobial drugs was recognized. The most common resistance was to streptomycin (24/32, 75%), ampicillin (19/32, 59.4%), tetracycline (15/32, 46.9%), spectinomycin (13/32, 40.6%) and sulfisoxazole (13/32, 40.6%). All the three Salmonella Kentucky isolates showed resistance to at least 8 antimicrobials. Out of the 12 Salmonella Braenderup isolates, 10 (83.3%) showed multidrug resistance to ampicillin, spectinomycin, streptomycin, sulfisoxazole, sulfamethoxazole/trimethoprim, amoxicillin/clavulanic acid and trimethoprim. Among the 8 S. Hadar isolates 7 (86.5%) showed antimicrobial resistance. All the 6 S. Dublin isolates were resistant to carbadox (100%). All the 6 S. Haifa isolates were resistant for at least ampicillin, streptomycin and tetracycline. Up to ten different antimicrobial resistances pattern was observed. Multiple antimicrobial drug resistance was observed in 23 Salmonella isolates (23.5%). The level of antimicrobial resistance was significantly higher for isolates from chicken carcass (18/29, 62.1%) and pork isolates (5/22, 22.7%) (p = 0.003). The findings of the present study ascertain that significant proportion Salmonella isolates have developed resistance for routinely prescribed antimicrobial drugs and poses considerable health hazards to the consumers unless prudent control measures are instituted.     

Detection of genetic variation among Indian wheat head scab pathogens (Fusarium spp./isolates) with microsatellite markers

Fusarium head blight (FHB) of wheat is responsible for extensive damage of wheat in humid and semi-humid regions of the world. Presently, FHB of wheat is a minor disease in India but due to global climate change, there is a chance that moist conditions and high humidity resulting from more rainfall during mid-anthesis could increase the susceptibility of wheat to Fusarium infection. For the present study, 27 isolates of three Fusarium spp. viz., Fusarium graminearum, Fusarium verticillioides and Fusarium oxysporum were isolated from naturally infected wheat sampled from Punjab, Himachal Pradesh and Wellington (Tamil Nadu) during 2000–2003. Genomic DNA was isolated from fresh mycelia using the CTAB method. Fusarium spp./isolates were analyzed with four newly developed microsatellite markers (MS-Fg1353, MS-Fg6808, MS-Fg307 and MS-Fg3654) and six previously published microsatellite markers (MS-Fg97, MS-Fc1, MS-Fg103, MS-Fg30, MS-Fg75 and MS-Fg90). All markers amplified a DNA fragment of variable length for different Fusarium spp./isolates. Microsatellite markers, MS-Fg103, MS-Fg103 did not amplify F. oxysporum and F. verticillioides isolates, respectively. MS-Fg307 amplified a fragment of 200 bp with F. graminearum isolates of Wellington. This study has shown that there is considerable genotypic variability among Fusarium spp./isolates causing FHB of wheat in India.     

Fungal diversity in agricultural soil under different farming management systems,with special reference to biocontrol strains of Trichoderma spp.

Fungal communities and their dynamics were investigated in relation to season, soil type and farming management practice. The research was done using soils from high- (H) and low-yield areas (L) of a field site cultivated with winter wheat under two different farming management systems (precision farming, P; conventional farming, C) over the vegetation period. Fungal diversity was analysed by cultivation-independent methods [direct extraction of DNA from soil followed by PCR amplification of a subunit of the 18S rDNA and fingerprinting (DGGE)] as well as cultivation-dependent techniques (isolation of pure cultures). The comparisons of the PCR amplicons by DGGE patterns showed no differences between the different sampling sites and no influence of the farming management systems. Only small differences were observed over the vegetation period. For cultivation purposes active hyphae were isolated using a soil-washing technique. The resulting isolates were subcultured and grouped by their morphology and genotype. In contrast to the cultivation independent approaches, clear site-specific and seasonal effects on the fungal community structure could be observed. However, minor effects of the different farming management techniques applied were visible for active populations. These results clearly indicate that the potential fungal community (including spores), investigated by the cultivation-independent approach, is almost entirely uninfluenced by the investigated factors, whereas active populations show a clear response to environmental changes. The most abundant group consisting of Trichoderma species was investigated in more detail using strain-specific genotype based fingerprinting techniques as well as a screening for potential biocontrol activity against the wheat pathogen Fusarium graminearum. The genotypic distribution as well as the potential biocontrol activity revealed clear site-specific patterns.     

评价水稻品种抗稻瘟病性两种方法的比较

本文比较了用稻瘟病菌的一个单孢菌株代表一个生理小种测定品种抗病频率和不分小种而直接用多个单孢菌株测定品种的抗病频率的优缺点.指出前者因同一生理小种内各菌株致病力有差异,以及抽样的随意性,测得的品种抗优势小种数实际上是抗菌株数,后者克服了前者的缺点,并得到自然病圃病情的验证,但仍有不足之处,有待改进.