Thermal Inactivation Point Research Articles

The occurrence of barley yellow dwarf disease in Japan.

Barley plants showing yellow dwarf symptoms were found in the barley fields at Nagaoka, Niigata Prefecture in May, 1980. The causal agent was transmitted in a persistent manner by Rhopalosiphum padi to gramineous plants but neither R. maidis nor Schizaphis graminum. Cereals such as barley, wheat, rye and oat exhibited typical yellow dwarf symptoms of stunting and either yellowing or red leaf discoloration. Other plants such as rice, maize, sorghum, Japanease millet, Job's tears and Italian ryegrass showed no symptoms but proved to be symptomless carriers of the agent. Partially purified preparations containing small spherical virus particles about 25nm in diameter were infectious when they were fed by aphids through membranes and the inoculated plants showed typical symptoms caused by barley yellow dwarf virus. Thermal inactivation point of the agent was between 65 and 70C. In the ultrathin sections, electron dense virus-like particles about 22nm in diameter were found only in phloem tissues of affected barley. Based on these results, the causal agent of the disease was identified as barley yellow dwarf virus.

Purification and properties of subterranean clover red leaf virus

Abstract Subterranean clover red leaf virus (SCRL V) was purified from infected peas using cellulase to assist in virus extraction. Yields of 0.5–3.0 mg/kg tissue were obtained. The virions were isometric with a diam. of 27 nm and sedimented as a single component of 114 S. The mean A260/A280 of purified preparations was 1.85. Apterae of Aulaeorthum solani (Kltb.) when fed on purified preparations through parafilm membranes were able to acquire and transmit virus. Purified virus had a dilution end point of 1.36 µg/ml, a thermal inactivation point between 55 and 60°C, and longevity in vitro of greater than 14 days. Gel electrophoresis of disrupted virions revealed that the coat protein was a single polypeptide with a molecular weight of 22 600. An antiserum with a homologous titre of 11256 in gel diffusion tests was prepared. SCRL V was shown to be serologically very closely related to soybean dwarf virus and less closely to bean leafroll, legume yellows, potato leaf roll, and tomato yellow top viruses. A m...

A Sap-transmissible, Defective Form of Tomato Spotted Wilt Virus

SUMMARY After multiple sap transmissions two isolates of tomato spotted wilt virus (TSWV) lost the characteristic particles, and amorphous, more or less diffuse masses were observed in the cytoplasm of cells. The amorphous material, which had previously been described associated with normal virus particles, could also be found in pellets from extracts of infected plants. Isolates of the ‘amorphous’ type had the same thermal inactivation point as those of the normal ‘particulate’ type. It is suggested that the ‘amorphous’ type is a defective form of TSWV.

Rice necrosis mosaic

Rice necrosis mosaic virus was observed in rice cultivarTaichung (Native) 1 at maximum tillering stage. The disease was transmitted by sap and soil.Nephotettix virescens, Nephotettix nigropictus andNilaparvata lugens failed to transmit the disease. Thermal inactivation point, dilution end point and ageingin vitro have been studied. Yield reduction due to this virus varied from 12·7 to 100% on different rice cultivars tested. Disease was more common in upland and directly seeded crop. The virus produced granular x-bodies in inner epidermis of leaf sheath of infected plants.

Limited value of the thermal inactivation point, longevity in vitro and dilution endpoint as criteria for the characterization, identification and classification of plant viruses.

Published data on the thermostability, longevity in vitro, and tolerance to dilution of viruses in sap from infected plants have been analyzed. It appears that none of these properties is a reliable criterion for virus classification or identification.

Some properties of Xanthomonas campestris pv. campestris phage.

Xanthomonas campestris pv. campestris phages (3 isolates of phage S, K and '76) were isolated from black rot diseased leaves of cabbage, cauliflower and turnip, and some of their fundamental properties were investigated. The particle of phage S was tadpole-like with a polyhedral head of about 50×60 nm and a tail of about 110×10 to 12 nm. Phages S and K attacked specifically X. campestris pv. campestris, but not X. campestris pv. citri, pv. cucurbitae, pv. oryzae, pv. phaseoli and pv. pruni. Phages S and K showed different host range to bacterial isolates of X. campestris pv. campestris. The thermal inactivation point of phage S was 53 C in distilled water and 65 C in potato ring-rot liquid medium by 10 min incubation. Phage S was more stable in its lytic activity in potato ring-rot liquid medium or in phosphate buffer than in distilled water. Phage S was also stable at pH 7.0, but not at pH 4.9 or 9.1. Throughout all conditions of different three dispersants and five pH levels phage S was more stable at 5 C than at 28 C. One-step growth experiments showed that multiplication of phage '76 was optimal at 28 C. The latent period, rise period and average burst size in the case of single infection were 75 min, 40 min and 13 plaque forming units, respectively. At 30 C or at the temperatures below 26 C, however, the latent period was prolonged and the average burst size became smaller.

果肉かっ変症状を呈したナスから分離されたキュウリモザイクウイルス

A strain of cucumber mosaic virus (CMV) was isolated from eggplants showing necrotic symptoms on fruits and mosaic on leaves, and the virus was confirmed to be a causal agent of these symptoms. The virus had characteristics as follows: 1) large necrotic lesions and veinal necrosis on inoculated leaves with systemic symptoms either necrosis or mosaic on Vigna sinensis and Phaseolus vulgaris. 2) systemic infection on radish and Chinese cabbage, etc. without any symptoms. 3) spherical particles about 30 nm in diameter. 4) positive reaction to CMV-Y antiserum in agar-diffusion test. 5) thermal inactivation point about 65 C. From these results, it was concluded that the virus was one of the strains of CMV systemically infectious to leguminous and cruci-ferous plants.

Distribution, host range, properties and purification of cassava latent virus, a geminivirus

SUMMARYCassava latent virus (CLV) is almost entirely confined in East Africa to upland cassava‐growing areas west of the Rift Valley, where it is often associated with cassava mosaic disease (it was isolated from 27 of 38 cassava plants with mosaic, but not from 24 without mosaic). However, it is not the causal agent, because it was not recovered from any of 31 mosaic‐diseased plants in coastal districts. All attempts to return CLV to cassava failed.The host range of CLV appears to be limited to Euphorbiaceae (Manihot) and Solanaceae (Nicotiana, Datura, Nicandra, Solanum). N. clevelandii proved the most useful assay and propagation host. The dilution end‐point of CLV was about 10‐3, thermal inactivation point about 55°C, and longevity in vitro about 3 days.CLV was purified by clarification of leaf extracts with butanol/chloroform mixtures. Purified preparations (A 260/A 280 ratio c. 16) contained numerous 30 20 nm paired particles with a sedimentation coefficient (s20w) of 76 S. Treatment with RNase and DNase showed that the viral nucleic acid is DNA; CLV closely resembles maize streak virus but is not related to it serologically. The cryptogram for CLV is D/1: 0.8/*: S/S: S/*, geminivirus group.

Ein Beitrag zur Charakterisierung des Spargel-Virus 2

In host range investigations with 152 plant species of 37 families, 96 species from 28 families proved to be experimentally susceptible to asparagus virus 2 (AsV 2). From these, 82 species of 26 families were systematically infectible and 14 species of 10 families only locally. Most frequently were symptomless systemic infections. Of 86 species, their susceptibility for AsV 2 was unknown before. The number of families that contant experimental hosts of the virus increased from 11 to 33. Transmission of AsV 2 was neither possible with Myzus persicae nor with Cuscuta californica or C. campestris. AsV 2-infected mother plants transmitted the virus by about 40 per cent to their seedings. Open-pollinated plants, not infested by AsV 2, showed 3 to 22 per cent of infected seedings. Mechanical back-transmission of AsV 2 from test plants to asparagus succeeded only in one case. The properties of the virus in vitro were as follows: thermal inactivation point between 64 and 66 degrees C, dilution end point between 10(-3) and 10(-4), stability in sap, stored at room temperature, up to 96 hours. Serological investigations demonstrated no relationship to the virus to numerous other viruses. An antiserum with a titer of 1 to 16 was useful for the detection of AvV 2 in asparagus sap. Electron microscopical investigations proved for the virus isometric particles for the first time. In negatively stained preparations they had a diameter of 27 nm.

Host plant reactions, physical properties and serology of three isolates of Andean potato latent virus from Peru

SUMMARYThree isolates of Andean potato latent virus (APLV) (Caj, Hu, Ay) each infected twenty‐seven species of plants in the families Amaranthaceae, Chenopodiaceae, Cucurbitaceae and Solanaceae but differed somewhat in the symptoms they induced. Nicotiana bigelovii and N. clevelandii proved the most useful diagnostic hosts. Symptoms were sometimes produced by all three isolates in cultivated and wild potatoes. In sap from systemically infected N. bigelovii and N. clevelandii leaves, all three isolates remained infective when diluted to 10‐6 and when stored at room temperature for at least 3 wk. The thermal inactivation points were 65–70 °C for Hu and Ay, but 75–80 °C for Caj. All three isolates differed serologically from Col, the original isolate of APLV, forming spurs in gel diffusion tests. No serological difference was found between Hu and Ay, but both formed spurs in reciprocal reactions with Caj. The data from light absorption, particle morphology and protein molecular weight for Caj, Hu and Ay are similar to those reported for other tymoviruses. APLV was found widespread in Andean countries.

Glitoria yellow vein virus, a tymovirus from Kenya

SUMMARYClitoria yellow vein virus (CYW) was found in Clitoria ternatea and Abrus precatorius in coastal districts of Kenya, but was not detected in food legume crops. When transmitted by inoculation of sap, CYW infected many species in the Papilionaceae, commonly causing yellowing of secondary and smaller leaf veins. All the economically important food legumes grown in the area of occurrence were very susceptible, so that CYW is potentially very important. The virus also infected okra (Hibiscus esculentus) and species in the Solanaceae, but none of many species of Cucurbitaceae.CYW is serologically closely related to cocoa yellow mosaic and kennedya yellow mottle viruses, and more distantly to okra mosaic and desmodium yellow mottle viruses. Other properties of CYW^ typical of the tymoviruses include particle morphology (particle diameter c. 28 nm; two components) with sedimentation coefficients of 50S (top) and 109S (bottom); molecular weight of protein sub‐units c. 20000; thermal inactivation point c. 72 oC; and longevity in vitro c. 3 wk.

DNA Viruses of Higher Plants

This chapter surveys the known properties of the caulimoviruses, along with pointing out their unique nature and providing an aid for the recognition and characterization of these viruses as new members of the group are encountered. The caulimorivuses cause mosaic–mottle types of diseases of their plant hosts that are not conspicuously different from diseases induced by an assortment of other plant viruses. The diseases are economically important on a number of cultivated crops and the viruses are widely distributed throughout the temperate regions of the world. The viruses are most conveniently identified by their restricted host ranges, relatively high thermal inactivation points, aphid transmissibility, morphology, serology, and the induction of characteristic inclusion bodies. The viruses are transmitted mechanically and by aphids in a stylet-borne manner, but exhibit a somewhat anomalous behavior in the vector. The chapter also discusses the various aspects of transcription, translation, and DNA replication of the DNA viruses. DNA replication is much more complicated than RNA synthesis and the viruses are dependent on host functions for the replication of their genomes.

Tentative description of Hippeastrum latent virus in Hippeastrum hybridum plants and differentiation from Hippeastrum mosaic virus

In mosaic-diseased plants ofHippeastrum hybridum two viruses were found. One virus with a normal length of 706 nm caused local lesions onHyoscyamus niger test plants and mosaic symptoms in the leaves ofH. hybridum. This virus was identified with theHippeastrum mosaic virus (HMV) (*/*∶*/*∶E/E∶S/*) and had a dilution end point between 10−3 and 10−4, a thermal inactivation point between 55–60°C and a longevity at room temperature of 28–32 hours. The second virus had a normal length between 584 and 611 nm depending on the method used. It caused local lesions onGomphrena globosa andChenopodium quinoa leaves, and after inoculation ofH. hybridum was found to be present without showing symptoms. It was readily purified from inoculated leaf tissue ofC. quinoa andNicotiana clevelandii by differential centrifugation and ofH. hybridum by density-gradient centrifugation. Purified virus had an absorption minimum at 242 nm, a maximum at 262 nm and a 260/280 absorption ratio of 1.19. The dilution end point was between 10−3 and 10−4, the thermal inactivation point between 70 and 80°C and the longevity in vitro at room temperature 28–32 hours. Although no direct comparisons have been made with other members of the potexvirus group, the virus seems to be a new one now namedHippeastrum latent virus. Both viruses were not seed-borne.

Studies on tomato aspermy virus fromChrysanthemum indicumL. in New Zealand

Abstract Tomato aspermy virus was found in chrysanthemum in New Zealand for the first time, in commercial gardens in Christchurch, Wanganui, and Auckland. The virus was transferred experimentally to marigold, nasturtium, aster, capsicum, chrysanthemum, tamarillo, lettuce, tomato, Nicotiana glutinosa L., Chenopodium amaranticolor Coste & Reyn., tobacco, black nightshade. New Zealand spinach, and zinnia. The longevity of the virus was between 7 and 11 days and the thermal inactivation point between 65° and 70°c. The dilution end point of the virus was between 1–50 000 and 1–100 000. The virus was transmitted by the green peach aphid.

Host range and properties of tobacco stunt virus

Tobacco stunt virus (TSV) was mechanically transmitted to 41 species in 9 families: i.e., Aizoaceae, Amaranthaceae, Apocynaceae, Caryophyllaceae, Chenopodiaceae, Cucurbitaceae, Leguminosae, Pedaliaceae, and Solanaceae. TSV remained infective for 60 h in 0.001 M 1-phenylthiosemicarbazide (1-PTC) in 0.01 M phosphate buffer, pH 6.8, but was infective only immediately after extraction in phosphate buffer. TSV in 1-PTC-phosphate buffer had a thermal inactivation point between 75 and 80 °C and a dilution end point between 10−2 and 10−3. Comparative studies made on reaction of host plants, serological reaction, and cross protection indicate that TSV is unrelated to a California isolate of tobacco necrosis virus.

Studies on potato virus X strains isolated from Peruvian potatoes

Four strains of PVX from Peruvian potatoes were inoculated to 17 species of indicator plants and to several potato cultivars and wild tuber-bearingSolanum species. Only one induced the typical symptoms of this virus in indicators. The rest induced mild mosaic in most solanaceous hosts. Dilution end-point, thermal inactivation point and longevity ‘in vitro’ were, in general, within the expected range for this virus; however, one strain had a dilution end-point above 10−6 and another, a thermal inactivation point below 66°C. All Peruvian cultivars tested were susceptible and 4 sometimes reacted with top necrosis. It was possible, from this top necrotic reaction, to deduce that the 4 strains belong to groups 2 and 3 of Cockerham's classification of PVX strains. The highly resistant clone USDA 41956 was also resistant to all these strains.

Soybean virus Z: its characteristics and taxonomy.

Soybean virus Z is a hitherto undescribed virus of soybeans found in Australia. It has a limited host range, attains a low concentration in plants and has a thermal inactivation point of 65 degrees. It has flexuous filamentous particles with a modal length of 610 nm and forms amorphous inclusions, but no pinwheels, in infected cells. It has not been transmitted by aphids or by seed. Its genome is RNA with the composition G23, A26, C25, U26, and its coat protein weights about 2.7 X 104. This virus seems to be unrelated to previously described viruses of soybeans, and does not fall into any of the described virus groups with similar particles.

The properties of a few isolates of the sour cherry necrotic ringspot virus

Results of the investigation of four isolates of the sour cherry necrotic ringspot virus are presented in this paper. The isolates used caused characteristic symptoms on woody indicators Bing, Montmoreney, F 12/1, and on peach seedlings. The virus was transmitted mechanically to some herbaceous species: Antirrhinum majus, Cucumis sativus, Cucurbita maxima, Ghsnopodium quinoa, Crotalaria juncea, Momordica balsamina, Petunia hybrida and Leonorus sibiricus. The attempts to transmit the virus mechanically to further 23 herbaceous species were unsuccessful. The thermal inactivation point of the virus lies between 46 and 58 ~ and the dilution end-point between 10 -1 and 10 -~. The virus is stable in vitro at room temperature for more than one day. Individual virus isolates gave a positive immunological reaction with the Fulton's G antiserum. The investigation of the ringspot disease of cherries started when KEITT and CLAYTON (1939) and WILLISON et at. (1948) confirmed in the U.S.A. the viral nature of yellows and of necrotic ringspot disease of sour cherry. From this time on numerous papers deMing with the investigation of this problem were published. Mechanical transmission of the ringspot virus from sour cherries to cucumber (Cucumis sativus) accomplished by MOORE et al. (1948) was one of the important achievements in the study of these viruses which opened new possibilities of a further and nearer study of their pro- perties. FULTON (1957a, b, 1958, 1959) and WATERWORTH and FULTON (1964) divided ringspot viruses into two basic groups: the sour cherry necrotic ringspot virus (NRSV), strains A, F and G, and the prune dwarf virus (PDV), isolate B. In our previous papers we already described some results of the investigations on ringspot viruses in our laboratory (PAULEC~OVA-KR~- LIKOV~ and KEGLER 1967, PAULECttOV~-KR~LIKOV~ 1969). In this paper we present further results on the sour cherry necrotic ringspot virus.

Untersuchungen über ein Isolat des Chlorotischen Ringfleckenvirus der Kirsche: Investigations about an Isolate of the Chlorotic Ringspot Virus of Cherry

From bulgarian ‘Elton’ sweet cherry trees with olive-green and yellowish as well as brown necrotic leaf spots a virus (EVI) was isolated and characterized. The virus caused in sour cherry trees (var. ‘Sehattenmorelle’) a severe decline and in cucumber seedlings leaf enations; thermal inactivation point is about 55–60°C, dilution end point 1/40, longevity in vitro 2–3 days. Separation of the virus from normal proteins by different methods was unsuffieient and also electronmicroscopical demonstration. Serological cross reactions of chlorotic ringspot virus (CRV = prune dwarf virus) and EVI in gel diffusion tests demonstrated the identity of CRV and EVI. EVI is in addition to CNRV, RMV and YMV a further biological different isolate of CRV (PDV). Von bulgarischen Süßkirschenbäumen der Sorte ‚Elton‘ mit olivgrünen bis gelblichen und braunen nekrotischen Blattflecken wurde ein Virus (EVI) isoliert und charakterisiert. Das Virus führte bei Sauerkirsche (‚Schattenmorelle‘) zum Absterben der Bäume und bei Gurkenkeimlingen zu Laubblattenationen, der TIP lag bei 55–60°C, VEP bei 1/40 und BIV 2–3d. Das EVI konnte mit verschiedenen Reinigungsmethoden nur unvollständig von den Normal-proteinen getrennt werden. Die elektronenmikroskopische Darstellung war nicht möglich. Serologische Kreuzreaktionen des Chlorotischen Ringfleckenvirus (CRV = prune dwarf virus) und des EVI im Geldiffusionstest zeigten, daß die Viren identisch sind. Das EVI ist nach dem CNRV, RMV und YMV ein weiteres biologisch abweichendes Isolat des CRV (PDV).

Some properties of potato virus S isolated from Peruvian potato varieties

Potato virus S (PVS) was isolated from several Peruvian potato varieties showing different symptoms ranging from mild systemic mosaic to yellowing and bronzing of the lower leaves. The properties of PVS from the potato varietyMantaro in crude sap are as follows: thermal inactivation point between 56°C and 62°C, 6 days longevity in vitro at room temperature; and dilution end point between 10−4 and 10−5. This isolate had the unique property of giving systemic symptoms onChenopodium quinoa.