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1.
A range of selected PVY isolates that induce superficial necrosis on potato tubers, originating from several countries, were compared with standard strains of PVA, PVV and PVY. Biological properties (e.g., host range, aphid transmissibility and relationships based on cross-protection between virus isolates) were studied. PVYNN isolates differ from the normal PVYC, PVYN and PVO strains by their ability to infect Capsicum annuum but not Chenopodium amaranticolor and C. quinoa. All PVYNN isolates are transmissible by Myzus persicae , without any significant differences from one standard strain. These additional data confirm that these tuber-necrosing isolates belong to PVY. However, they could be ranged in a homogeneous and distinct group inside the PVYN group, based on the differences revealed in the host range, in addition to the specific ability naturally to induce necrosis on tubers.  相似文献   

2.
 马铃薯是我国重要粮食和经济作物。马铃薯Y病毒(potato virus Y,PVY)是危害马铃薯生产的重要病害。种植脱毒种薯是防治PVY最有效的途径。马铃薯种薯携带PVY问题严重,但种薯中PVY株系还不清楚。本研究利用PVY特异性抗体检测了7个马铃薯品种362个种薯,发现不同品种种薯带毒率差异较大,最高达12%。通过RT-PCR方法扩增获得了7个PVY分离物编码区全序列。重组分析发现7个分离物基因组均为重组型,根据重组位点的差异可以分为PVYNTN-NW(SYR-II型)、Rec-1、Rec-2和Rec-3等4种重组类型,后3种为新重组类型。系统进化分析发现,分离物HQH18G3-10与PVYNTN-NW(SYR-II型)处于同一个大的分支,但与中国PVY大田分离物聚集在一起形成一个相对独立的组,命名为PVYNTN-NW(CN型);其余6个分离物与数据库中的中国分离物聚集在PVYN-Wi组。这暗示PVY中国分离物具有相对独立的进化过程,PVY马铃薯大田分离物和种薯分离物进化上相近。所有分离物均能在珊西烟上引起典型叶脉坏死症状,HQH18G3-10引起的坏死症状最为严重。本研究首次报道了我国种薯内PVY发生情况,对分析病毒发生发展规律和防控具有借鉴作用。  相似文献   

3.
 马铃薯是我国重要粮食和经济作物。马铃薯Y病毒(potato virus Y,PVY)是危害马铃薯生产的重要病害。种植脱毒种薯是防治PVY最有效的途径。马铃薯种薯携带PVY问题严重,但种薯中PVY株系还不清楚。本研究利用PVY特异性抗体检测了7个马铃薯品种362个种薯,发现不同品种种薯带毒率差异较大,最高达12%。通过RT-PCR方法扩增获得了7个PVY分离物编码区全序列。重组分析发现7个分离物基因组均为重组型,根据重组位点的差异可以分为PVYNTN-NW(SYR-II型)、Rec-1、Rec-2和Rec-3等4种重组类型,后3种为新重组类型。系统进化分析发现,分离物HQH18G3-10与PVYNTN-NW(SYR-II型)处于同一个大的分支,但与中国PVY大田分离物聚集在一起形成一个相对独立的组,命名为PVYNTN-NW(CN型);其余6个分离物与数据库中的中国分离物聚集在PVYN-Wi组。这暗示PVY中国分离物具有相对独立的进化过程,PVY马铃薯大田分离物和种薯分离物进化上相近。所有分离物均能在珊西烟上引起典型叶脉坏死症状,HQH18G3-10引起的坏死症状最为严重。本研究首次报道了我国种薯内PVY发生情况,对分析病毒发生发展规律和防控具有借鉴作用。  相似文献   

4.
The susceptibility of 24 potato cultivars to soft rot caused by Erwinia carotovora subsp. atroseptica was assessed in a simplified form of a tuber slice test described previously. Freshly made wounds on tuber slices were inoculated with drops (0–02 ml) containing 108, 107 or 106 cells/ml and incubated aerobically for 3 days at 15° or 20°C. At 20°C differences between cultivars were clear at all concentrations but at 15°C less so at the lowest concentration unless incubation time was extended. The rank order of cultivar susceptibility was similar to that found in previous seasons.  相似文献   

5.
In an attempt to better understand the importance of tuber-borne inoculum in black dot development, several potato cultivars were inoculated with various Colletotrichum coccodes isolates. Symptoms developed first on underground organs (starting 2 weeks after inoculation on roots, and later on stolons and tubers) of inoculated plants; stem infections developed only after 7–10 weeks, depending on the cultivar. Infection with C. coccodes resulted in a reduction in numbers of stolons and tubers in cv. Bintje, but not in the later maturing cv. Roseval. Significant isolate by cultivar interactions were detected from the analysis of root symptoms after inoculation of three potato cultivars (Bintje, Spunta and Desiree) with five C. coccodes isolates. Such an interaction was also detected for stolon/tuber symptoms at the latest scoring date (98 days after inoculation), but not at earlier dates (58, 70 and 84 days after inoculation). These results suggest that protocols based on root colonization might be used for investigating cultivar response to black dot and pathogenicity of C. coccodes isolates, and that some specificity exists in the reaction of potato genotypes to this pathogenic fungus.  相似文献   

6.
According to EC regulations, imported material of tuber-forming Solarium spp. has to be tested for the absence of defined quarantine viruses. In order to allow an efficient and timesaving application of the quarantine inspection procedure, antisera have been developed and scrutinized for their use by the ELISA technique. The viruses concerned were Andean potato latent virus (APLV), Andean potato mottle virus (APMV), arracacha virus B oca strain (AVB-O), potato virus T (PVT) and tobacco ringspot virus Andean potato calico strain (TRSV-Ca). The results show that all viruses can be reliably detected by double-antibody sandwich (DAS) ELISA. The detection limits were in the range ≤ 1–32 ng ml−1. The strain specificity by DAS-ELISA of the antisera for APLV and APMV was overcome by mixing antisera from the different strains and strain groups, respectively. Strains C and Lm of APMV seemed to be serologically identical. A comparison of the suceptibility of several wild species of tuber-forming Solanum with that of several cultivars of Solanum tuberosum showed a higher frequency of infection in the wild species.  相似文献   

7.
To optimize mechanical inoculation of test plants as part of the regulated post-entry quarantine testing of stolon- and tuber-forming Solanum spp. (including potato), nine test plant species have been screened for their ability to detect 22 potato-infecting viruses. These included all the common mechanically transmissible potato viruses and most of the viruses found in potato incidentally. The symptoms observed after mechanical inoculation are shown for each combination of test plant species and virus. Under given conditions, Nicotiana occidentalis -P1 and Nicotiana hesperis -67A were found to detect reliably 20 and 18 out of 22 viruses respectively. These and former results on the seed-transmissible viruses and Andean potato mottle virus demonstrate that these Nicotiana species are very suitable for post-entry quarantine testing. Addition of either Chenopodium amaranticolor or Chenopodium quinoa to these two species may slightly extend the range of viruses. Therefore, using C. amaranticolor / C. quinoa , N. hesperis -67A and N. occidentalis -P1 for the biological screening of imported Solanum spp. will improve both the efficiency and the quality of post-entry quarantine testing.  相似文献   

8.
Sweet potato virus disease (SPVD) is the name used to describe a range of severe symptoms in different cultivars of sweet potato, comprising overall plant stunting combined with leaf narrowing and distortion, and chlorosis, mosaic or vein-clearing. Affected plants of various cultivars were collected from several regions of Uganda. All samples contained the aphid-borne sweet potato feathery mottle potyvirus (SPFMV) and almost all contained the whitefly-borne sweet potato chlorotic stunt closterovirus (SPCSV). SPCSV was detected by a mix of monoclonal antibodies (MAb) previously shown to react only to a Kenyan isolate of SPCSV, but not by a mixture of MAb that detected SPCSV isolates from Nigeria and other countries. Sweet potato chlorotic fleck virus (SPCFV) and sweet potato mild mottle ipomovirus (SPMMV) were seldom detected in SPVD-affected plants, while sweet potato latent virus (SPLV) was never detected. Isolates of SPFMV and SPCSV obtained by insect transmissions together induced typical symptoms of SPVD when graft-inoculated to virus-free sweet potato. SPCSV alone caused stunting and either purpling or yellowing of middle and lower leaves when graft-inoculated to virus-free plants of two cultivars. Similarly diseased naturally inoculated field plants were shown consistently to contain SPCSV. Both this disease and SPVD spread rapidly in a sweet potato crop.  相似文献   

9.
The biological and molecular relationships between a large number of Potato virus Y (PVY) isolates were examined, concentrating mainly on isolates associated with potato tuber necrotic ringspot disease (PTNRD). Following detailed analysis of the coat-protein gene, four main groups were identified which broadly corresponded to the phenotype of the different isolates. The groups comprised the ordinary strain (PVYO), the necrotic strain (PVYN), the C strain (PVYC) and a group of recombinant (between ordinary and necrotic) isolates. In the latter group, all members were associated with PTNRD. However, four nonrecombinant isolates were also identified which were associated with PTNRD or tuber necrosis. Three were from tubers showing PTNRD symptoms in the field, while the fourth originated from symptomless tubers, but could cause necrotic rings on tubers under glasshouse conditions. The results show that although coat-protein recombination is always found associated with the PTNRD phenotype, some nonrecombinant isolates have very similar biological properties.  相似文献   

10.
Interactions between Verticillium dahliae and Colletotrichum coccodes , major causal agents of potato early dying (PED) syndrome, were studied in four potato cultivars that differ in their susceptibility to these pathogens . Aseptic plantlets of Nicola, Desiree, Alpha and Cara were inoculated with identical concentrations of each pathogen or with a mixture of the pathogens, and grown for 4 weeks in a monitored growth chamber. Coinoculation of Nicola with both pathogens caused more severe foliar disease symptoms and crown rot and greater C. coccodes colonization, than inoculation with each pathogen separately. Significant reductions in weight and height were also observed in plants coinoculated with both pathogens, as compared with plants inoculated with each pathogen separately or noninoculated plants. In Desiree, more roots were covered with C. coccodes sclerotia and disease symptoms were significantly more severe in plants inoculated with both pathogens together. However, plant weight and height were similar to those of plants inoculated with C. coccodes only. In Alpha, disease symptoms and levels of sclerotia in the roots were not affected by simultaneous inoculation with both pathogens. Weight and height of all plants were similar, whether inoculated with each pathogen separately or with both pathogens together. In Cara, plants inoculated with the mixture or either pathogen alone were smaller than the noninoculated control. Disease symptoms and occurrence of sclerotia were similar in plants inoculated with the combination and with a single pathogen. Compared with the effects of inoculation with either pathogen, simultaneous inoculation with both pathogens can, in some cultivars, increase the incidence of PED syndrome and thus severely decrease yields.  相似文献   

11.
The population of Phytophthora infestans in Brazil consists of two clonal lineages, US-1 associated with tomatoes and BR-1 associated with potatoes. To assess whether host specificity in these lineages resulted from differences in aggressiveness to potato and tomato, six aggressiveness-related epidemiological components – infection frequency (IF), incubation period (IP), latent period (LP), lesion area (LA), lesion expansion rate (LER) and sporulation at several lesion ages (SSLA) – were measured on detached leaflets of late blight-susceptible potato and tomato plants. Infection frequency of US-1 was similar on potato and tomato leaflets, but IF of BR-1 was somewhat reduced on tomato. Incubation period was longer on both hosts with US-1, although this apparent lineage affect was not significant. Overall there was no host effect on IP. On potato, BR-1 had a shorter LP (110·3 h) and a larger LA (6·5 cm2) than US-1 (LP = 162·0 h; LA = 2·8 cm2). The highest LER resulted when isolates of BR-1 (0·121 cm2 h−1) and US-1 (0·053 cm2 h−1) were inoculated on potato and tomato leaflets, respectively. The highest values of the area under the sporulation capacity curve (AUSC) were obtained for isolates of US-1 inoculated on tomato leaflets (6146) and for isolates of BR-1 on potato leaflets (3775). In general, higher values of LA, LER, SSLA and AUSC, and shorter values of LP were measured when isolates of a clonal lineage were inoculated on their original host than with the opposite combinations. There is evidence that there are quantitative differences in aggressiveness components between isolates of US-1 and BR-1 clonal lineages that probably contribute to host specificity of P. infestans populations in Brazil.  相似文献   

12.
An apparatus is described for the control of humidity, air speed and temperature around detached potato leaflets and whole plants. Leaflets and plants inoculated with Phytophthora infestans were incubated in air at 15°C. Abundant sporangia were formed in an air speed of 0.3 × 10−3 m/s when the ambient humidity was 90–100% RH, but not at 85 or 80% RH. At air speeds of 5.5 × 10−3 and 13.7 × 10−3 m/s there were numerous sporangia at 100% RH, but not at 95–80% RH. The number of sporangia formed on leaflets kept in air flowing at 5.5 × 10−3 m/s with alternating humidities of 80 and 100% RH each for 12 h per day was intermediate between numbers formed on leaflets incubated at each humidity continuously, and higher than numbers formed at a constant 90% RH. Removing leaflets from plants before inoculation did not affect the number of sporangia produced.  相似文献   

13.
Endogenous levels of free and conjugated salicylic (SA) and gentisic (GA) acids, both putative signal molecules in plant defence, were analysed in order to investigate their involvement in the resistance of four potato ( Solanum tuberosum ) genotypes with different susceptibilities to Potato virus YNTN (PVYNTN) infection: the highly susceptible cv. Igor and its extremely resistant transgenic line, the extremely resistant cv. Sante and the tolerant cv. Pentland Squire. The lowest levels of free and conjugated SA were observed in the extremely resistant cv. Sante, while free GA, which was detected in all the other varieties, was absent. The extremely resistant transgenic cv. Igor contained the highest basal total SA level and the lowest level of total GA of all four cultivars. In susceptible cv. Igor, but not in resistant transgenic cv. Igor, a systemic increase of free SA was measured 1 day postinfection (dpi). Even more significant increases of free and conjugated SA and GA were detected 11 dpi when systemic symptoms appeared. In inoculated but not in upper noninoculated leaves of resistant transgenic cv. Igor, significant increase of SA conjugates occurred, but not before 11 dpi. The increase of SA and GA in susceptible cv. Igor could contribute to the general elevated levels of phenolic compounds as a response to stress caused by virus infection. It appears that basal levels of SA and GA do not correlate with resistance to PVYNTN in potato plants.  相似文献   

14.
Four mouse monoclonal antibodies (MAbs) against potato virus Y (PVY) were produced. MAb 4C1 reacted with four isolates of PVYNTN and only very weakly with one isolate of the necrotic strain of PVY (PVYN). It did not react with other isolates of the ordinary strain of PVY tested. MAb 2C9 reacted with all isolates tested and can be used to produce a specific diagnostic kit for routine PVY detection. Other MAbs had different specificities and reacted with isolates of various strains of PVY. MAbs did not react with seven other members of the Potyvirus group including potato virus A. A MAb-based ELISA, using MAb 4C1, was devised and shown to detect PVYNTN specifically.  相似文献   

15.
Benzothiadiazole (BTH), as Bion WG50, and acetylsalicylic acid (ASA) treatments of potato foliage of field- and glasshouse-grown potato plants were compared for control of two foliar diseases, early blight ( Alternaria solani ) and powdery mildew ( Erysiphe cichoracearum ). The effect of these treatments on harvested tubers wound-inoculated with the dry rot fungus ( Fusarium semitectum ) was also evaluated. BTH (50 mg a.i. L−1) gave almost complete control of both foliar pathogens on inoculated glasshouse-grown plants and reduced the severity of leaf spotting diseases (mainly early blight) in the field. BTH (100 mg a.i. L−1) and ASA (400 mg a.i. L−1) reduced the severity of dry rot in field-grown tubers in some post-harvest wound-inoculated treatments but not others and a similar reduction occurred with tubers inoculated post-harvest from BTH-treated plants grown under glasshouse conditions. BTH treatment increased β-1,3-glucanase activity in leaves > stem > tubers > stolons but not in roots. Increased enzyme activity was recorded for up to 45 days post-treatment.  相似文献   

16.
The occurrence of three viruses in hop (Humulus lupulus) in China   总被引：1，自引：0，他引：1  
J YU  Y LIU 《Plant pathology》1987,36(1):38-44
Forty-two percent of leaf samples taken from hop cv. Qingdao Dahua growing in plantations in northeastern China in 1983-1984 were infected with hop mosaic virus (HMV) and/or hop latent virus (HLV). Mosaic or line-pattern symptoms were seen in some plants but only in spring and it is uncertain if the symptoms were caused by either virus which appeared in our studies to be similar, both serologically and in host range, to HMV and HLV described in Europe and North America. In host range studies, HMV infected Nicotiana clevelandii systemically without inducing symptoms. Occasionally it caused chlorotic spots in the inoculated leaves of Chenopodium quinoa and brown star-point lesions in inoculated leaves of Phaseolus vulgaris cv. Topcrop, The virus was purified by PEG precipitation from extracts of N. clevelandii plants; yields were about 40-120 mg/kg fresh leaves. The virus contained a single protein (estimated molecular weight 34 200) that was estimated to contain 272 amino acids with no methionine, and a single RNA species (estimated molecular weight 295 x 106) that represented c. 6% of the particle weight. HLV sometimes caused inconspicuous chlorotic spots in inoculated leaves of C. murale and local pinpoint lesions in P. vulgaris in winter only. A virus similar to alfalfa mosaic virus was isolated from leaves of hop cv. Golding and caused systemic necrotic symptoms in C. quinoa and C. amaranticolor , and systemic chlorotic spots in hop cv. Styrian.  相似文献   

17.
Detailed characterization of a number of isolates of PVYSYR, a novel recombinant strain of Potato virus Y (PVY) from Syria, was conducted to elucidate their origin, assess their significance and achieve a final classification of PVYSYR. Recombination analysis grouped isolates of PVYSYR into three recombination patterns, SYR-I, SYR-II and SYR-III, which varied in the first 700 nucleotides of their genomes, with the second recombination pattern, SYR-II, the most frequent. PVYSYR isolates shared highest genomic identity and close phylogenetic relationships with PVYNTN and PVYNW isolates from Syria, suggesting a common origin and local emergence of these isolates in Syria. All PVYSYR isolates (total of 20) induced tobacco veinal necrosis, but reacted to a PVYO monoclonal antibody, typical characteristics of the previously reported PVYNW (or PVYN:O). In potato, however, four isolates tested (one of SYR-I and three of SYR-II) induced potato tuber necrotic ringspot disease (PTNRD), which is the characteristic phenotype of PVYNTN. Given the shared properties of SYR-I and SYR-II isolates with PVYNTN and PVYNW, it was decided that they represent a new recombinant strain of the PVYN strain group, with the proposed name PVYNTN-NW. The classification of SYR-III will be possible only after testing the phenotype in potato. The high prevalence of PVYNTN-NW in potatoes and weeds, as well as its ability to induce PTNRD, demonstrates its importance and the necessity for its control.  相似文献   

18.
The effect of cultivation temperatures on the resistance reaction to three Potato virus Y strains (PVYO, PVYN and PVYNTN) in potato cultivars carrying Rychc was examined. When potato plants carrying Rychc were cultivated at 22 °C, a few small necrotic spots developed on inoculated leaves by 5 days after mechanical inoculation (dpi), and systemic infection of a few symptomless plants was confirmed at 28 dpi by IC‐RT‐PCR. At 28 °C, distinct necrotic spots developed on inoculated leaves by 5 dpi, and systemic symptoms occasionally appeared at 28 dpi. Thus, high temperature weakens Rychc‐conferred resistance. However, the incidence of systemic infection and the titre of virus in resistant cultivars at 28 °C were lower than in a susceptible cultivar. In graft inoculation under high summer temperatures, some plants developed necrosis on the leaves and stem, but PVY was barely detected by RT‐PCR in leaves on potato carrying Rychc. When seedlings from progeny tubers of plants that were inoculated with PVY and grown in a greenhouse at >30 °C in the daytime were examined by ELISA and IC‐RT‐PCR, PVY was not detected in cultivars carrying Rychc. These results show that Rychc confers an extreme resistance to PVY strains occurring in Japan.  相似文献   

19.
Aggressiveness of Verticillium dahliae isolates from three vegetative compatibility groups (VCGs) was tested on potato and tomato. VCG4B was the most aggressive to potato and VCG2A was the most aggressive to tomato; VCG2B was the least aggressive to both potato and tomato. In potato, disease incidence, symptom severity and colonization index of stem segments were significantly higher in plants inoculated with VCG4B isolates than in those inoculated with VCG2B and VCG2A isolates. Inoculation with VCG4B and VCG2A decreased plant height and fresh weight more than inoculation with VCG2B. In tomato, VCG2A caused significantly more severe symptoms than either VCG4B or VCG2B. The colonization index in tomato plants inoculated with VCG2A was also significantly higher than in those inoculated with VCG4B and VCG2B. Similar patterns of relative aggressiveness were observed in potato and tomato when the pathogenicity of isolates of various VCGs, each originating from a specific host (cotton, potato or eggplant), was compared.  相似文献   

20.
V. Raggi 《Plant pathology》2000,49(2):179-186
Tobacco cv. Havana 425 acquired resistance to a compatible isolate of Erysiphe cichoracearum after infection by a strain of potato virus Y (PVYN) that causes veinal necrosis; another common strain (PVYO) that does not cause necrosis gave less protection. Hydroxyproline-rich glycoproteins (HRGPs), believed to be involved in resistance, were determined by analysing hydroxyproline (Hyp) in purified cell walls. Hyp content increased significantly in PVYN-protected leaves, compared with untreated controls, 2–4 days after necrotic lesion symptoms developed. No further increase in Hyp was noted in PVYN-protected leaves after E. cichoracearum challenge. Hyp increases were significantly higher in protected leaves of plants showing symptoms on day 7 than on day 10. Infection with the PVYO strain caused significant decrease in Hyp content, compared with uninoculated controls. Inoculation of virus-free plants with E. cichoracearum induced moderate and transitory Hyp increases on day 2 or 3, followed by a quick decrease associated with a weak response by the compatible host. It is suggested that HRGP accumulation induced by PVYN (but not by PVYO) causes changes in the host cell wall that result in resistance to E. cichoracearum .  相似文献   

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