摘要:

AbstractFive pectolytic bacteria were isolated from roots and petioles of sugar beet exhibiting soft rot and vascular necrosis symptoms that were collected from different fields in El‐Minia Governorate, Egypt. Inoculation of the bacteria into sugar beet roots through wounded crowns or injured lateral roots reproduced soft rot and vascular necrosis symptoms. According to their biochemical and physiological characteristics, pathogenicity tests, fatty acid composition analysis, and electron microscopy, the bacteria were identified asErwinia carotovorassp.betavasculorum.This is the first report of the disease in Egyp

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1996.tb01520.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractThe Iranian isolate of bermudagrass etched‐line virus (BELV‐I), purified by low‐pH treatment of infected bermudagrass sap followed by several cycles of differential centrifugation and sucrose density‐gradient centrifugation, formed two components in density‐gradient columns. The top component consisted of empty protein shells. It had a major structural protein of c. 22 kDa and a minor of c. 25 kDa. The weight of the nucleic acid present only in bottom component particles, was calculated to be 1.82 × 106Da. OnlyAconurella prolixa(Leth.) was able to transmit the virus under experimental conditions or contained the virus in natural populations. In ELISA tests the virus titer in the vector increased rapidly between days 14 and 29 after acquisition, results indicating a propagative relationship. BELV‐1 was serologically closely related to the Moroccan isolate of BELV, and related to the American but not to the Costa Rican isolate of maize rayado fino virus (MRFV). Several graminaceous species were found to be experimental or natural hosts

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1996.tb01521.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractMonoclonal antibodies (mAbs) were prepared against a yam mosaic virus (YMV) isolate from the Côte d'Ivoire. Symptomatology, Western immunoblotting, and ELISA were used to discriminate 69 isolates of YMV originating from differentDioscoreaspecies and from various yam producing areas. These isolates induced two types of symptoms, were of four different electrophoretic mobilities and formed two serogroups. These results suggest that at least six differetit groups of isolates exist, three of which infect the main cultivated species in various geographical areas while two others were from unusual samples in our collection. An isolate from ‘Pilimpikou Yam’ from Central Burkina Faso was serologically distinct. It is concluded that there is a significant variability among yam virus isolates which is unrelated to the origin of the isolate (geographic or host species). It is suggested that precautions should be taken in order to avoid international exchange of infected mate

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1996.tb01522.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractA split‐split plot design was used to study the effect of lodging and time of harvest on the formation of theFusariumtoxin deoxynivalenol (DON). Altogether 19 experimental fields were included in the study, which was carried out over the period 1991–1993. There were two cultivars each of barley and oats tested. Half of each field was lodged artificially using a drum roller to flatten the crop about 3 weeks after ear emergence. The grain was harvested at the stage of mealy ripe and about 15 and 30 days after. The DON concentratioti in the grain was in descending order influenced by lodging, cultivar, experimental field, year and time of harvest. When paired plots were compared a distinct increase (more than 65%) in the DON concentration was found in samples from 49% of the plots with lodging compared with their pair plot. Both a decrease and an increase in the DON content were detected in the period from the first time of harvest to the second and third titne of harvest. The overall contamination level of DON was found to be higher in the samples of barley compared to o

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1996.tb01523.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractGlucan preparations were obtained by transformation of laminaran from the algaLaminaria cichorioideswith endo‐β‐1,3‐glucanase from marine mollusks. These preparations, like those of other sources, have an inhibitory effect on tobacco mosaic virus (TMV) infection of detached leaves of local and systemic host tobacco

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1996.tb01524.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractThe complementary sense promoter C1that regulates the transcription of replicase gene in geminiviruses was cloned from tomato yellow leaf curl virus. A transcription fusion of β‐glucuronidase gene (GUS) coding sequence to complementary sense promoter, that replaced the viral replicase coding sequence, was constructed. Protoplasts ofNicotiana tabacumwere electroporated to introduce the GUS gene controlled by the C1promoter. The level of GUS transient gene expression was enhanced by the increase of the plasmid DNA concentration. Fluorometric GUS assays showed that the C1promoter has a lower expression compared to the e35S promoter. Bombardment of the constructed plasmid. containing Cl promoter‐GUS ORF‐NOS terminator (pKSIR‐E), was performed to different plant genetic backgrounds and followed by the histochemical GUS assays. The results showed that there were GUS activities expressed in tomato (Lycopersicon esculentum), tobacco (Nicotiana tabacum) and datura (Datura stramonium), as host plants. While in non‐host plants, the GUS activities were observed in faba bean (Vicia faba) and squash (Cucurbita pepo), as examples of dicot plants, but not in maize (Zea mays) as a representative o

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1996.tb01525.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractSerological and biological comparisons were made among 45 seed‐borne isolates of blackeye cowpea mosaic (BICMV) and 54 seed‐borne isolates of cowpea aphidborne mosaic (CAbMV) potyviruses derived from cowpea seedlots or young nursery‐grown seedlings comprising 2112 germplasm accessions or pre‐introduction seedlots ofVigna unguiculata.Isolates were identified by DAS‐ELISA using polyclonalimmunoglobulinG specific for these viruses. Twenty isolates of BICMV and 32 isolates of CAbMV were also compared by ACP‐ELISA with selected monoclonal antibodies and by SDS‐immunodiffusion. By all approaches, isolates of BICMV were clearly distinguished from CAbMV isolates. Isolate comparisons on selected cowpea genotypes (TVu‐401, TVu‐1582, TVu‐2657, and TVu‐3433) partitioned most isolates into two distinct groups. A few isolates seed‐borne in Indian cv. Pusa Phalguni, however, were clearly BICMV by all serological tests, but behaved as CAbMV in definitive cowpea genotypes. Although BICMV is generally considered to be a ‘new world virus’, both BICMV and CAbMV occurred inV. unguiculataseedlots originating in ‘old‐world regions’, including Afghanistan, Botswana, Nigeria, Senegal, and South Africa. Seedborne CAbMV was isolated from 6 of 155 tested USV. unguiculataGermplasm accessions originating, respectively, in Afghanistan (2), Botswana

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1996.tb01526.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractSeven isolates ofIdriella bolleyiobtained from adventitious roots ofAgrostis palustrisdisplaying symptoms of thinning, low vigor, and death of turf in a random, nondescript pattern were evaluated for their ability to infect adventitious roots ofA. palustrisunder high and low temperature regimes and to affect plant growth and symptom expression. All isolates ofI. bolleyiinfected roots under high and low temperature regimes and all but one isolate decreased shoot and root dry weight. Isolate IB‐2 decreased dry weight under low temperatures, but not under high temperatures. Stolon growth of root‐inoculated plants increased or remained unchanged among plants subjected to high temperature; stolon growth decreased on plants subjected to low temperature. Most isolates ofI. bolleyidecreased the chlorophyll content of leaves of plants subjected to high temperature; chlorophyll content of leaves of inoculated plants subjected to low temperature remained unchanged. Hyphal growth was observed on inoculated adventitious roots and was accompanied by dark clusters of fungal cells and chlamydospores on the epidermis and cessation structures within the cortex. Vascular tissues were not penetrated byI. bolleyi.It was concluded thatI. bolleyican infect adventitious roots ofA. palustrisas a minor root pathogen and alter root and shoot gro

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1996.tb01527.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractRhopalosiphum padiandSitobion avenaealates were collected from colonised winter cereals and maize in N.E. Spain and fed on young wheat plants for 7–10 days in the glasshouse. Then, aphids were killed and the plants on which aphids reproduced were kept in the glasshouse for 30–40 days. ELISA of infested plants was made using polyclonal and monoclonal antisera against PAV‐, RPV‐ and MAV‐like isolates. In autumn and spring, MAV serotypes were transmitted byS. avenaeandR. padi, mainly in mixed infections with PAV serotypes. This possibly explains the high frequency of MAV‐like isolates and their previously recorded year‐to‐year stability in maize, grain and forage winter cereals and cereal volunteers. PAV‐like isolates were rarely transmitted byS. avenaeand its spread thus depends almost exclusively onR. padi.These results confirm the importance of forage cereals and cereal volunteers as virus sources for winter cereal infection in the autumn, and the latter as a source of BYDV fo

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1996.tb01528.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractTomato plants displaying symptoms of yellowing and leaf curling were analysed for the presence of geminiviruses. Two distinct geminiviruses were present in the plants studied. One had a genome size and coat protein gene sequence similar to the Israeli strain of tomato yellow leaf curl virus (TYLCV), while the other had a smaller genome size than TYLCV that could not be amplified using primers specific for Israeli TYLCV. The presence of the Israeli strain of TYLCV has been reported in other Caribbean islands, but not in Southern Florida (USA) which is close to those islands where TYLCV has been detected. This suggests that the introduction of the Israeli strain of TYLCV to the Caribbean area may have occurred within recent times.

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1996.tb01529.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY