Mosaic patterns of transgene expression in plants

The review describes the phenomenon of mosaic transgene (gene) expression in plants. Parallels with the mosaic transgene (gene) expression in other organisms are presented. Parallels with the mosaic patterns of gene (transgene) expression in other organisms (Drosophila, transgenic animals, and others) are made.     

国家种质库保存大豆和菜豆种质的种传病毒检测

以国家种质中期库提供的300份大豆、100份菜豆种质为材料,分别采用血清学和分子生物学方法,对种传病毒的种类进行了检测。结果表明:在大豆种质中检测出大豆花叶病毒(SMV)、黄瓜花叶病毒(CMV)、苜蓿花叶病毒(AMV)3种病毒,阳性检出率分别为25.33%(76份)、13.67%(41份)和4.67%(14份)。大豆种质中还存在大豆花叶病毒与黄瓜花叶病毒、大豆花叶病毒与苜蓿花叶病毒的复合侵染。在菜豆种质中检测出菜豆普通花叶病毒(BCMV)阳性材料92份,种质带毒率高达92%。这些信息将会对今后采取相关措施提高国家种质库保存的豆类种质的质量提供帮助。     

Mosaic patterns of transgene expression in plants

The review describes the phenomenon of mosaic transgene (gene) expression in plants. Parallels with the mosaic transgene (gene) expression in other organisms are presented. Parallels with the mosaic patterns of gene (transgene) expression in other organisms (Drosophila, transgenic animals, and others) are made.     

Difference in the retinal cone mosaic pattern between zebrafish and medaka: cell-rearrangement model

In fish retina, four kinds of photoreceptor cells (or cones) are two-dimensionally arranged in a very regular manner, forming cone mosaics. Mosaic pattern differs between species--two typical patterns are "row mosaic" and "square mosaic", exemplified by the cone mosaics in zebrafish and in medaka, respectively. In this paper, we study a cell-rearrangement model. Cells with pre-fixed fate exchange their locations between nearest neighbors and form regular mosaic patterns spontaneously, if the adhesive force between nearest neighbors and between next-nearest neighbors depend on their cell types in an appropriate manner. The same model can produce both row and square mosaic patterns. However, if the cell-cell interaction is restricted to nearest neighbors only, the square mosaic (medaka pattern) cannot be generated, showing the importance of interaction between next-nearest neighbors. In determining whether row mosaic (zebrafish pattern) or square mosaic (medaka pattern) is to be formed, two shape factors are very important, which control the way adhesions in different geometric relations are combined. We also developed theoretical analysis of the parameter ranges for the row mosaic and the square mosaic to have higher total adhesion than alternative spatial patterns.     

Application of a Simplified Molecular Protocol to Reveal Mixed Infections with Begomoviruses in Cassava

Samples of cassava leaves exhibiting severe symptoms of cassava mosaic disease (CMD) were collected with the PhytoPASS kit in fields surrounding the city of Bujumbura (Burundi). These materials were then sent to Belgium for polymerase chain reaction determination of the CMD begomoviruses inducing the observed symptoms. Different pairs of specific primers were used to amplify DNA sequences specific to African cassava mosaic virus (ACMV), East African cassava mosaic virus (EACMV), East African cassava mosaic Cameroon virus (EACMCV), East African cassava mosaic Malawi virus (EACMMV), East African cassava mosaic Zanzibar virus (EACMZV), the Uganda variant of East African cassava mosaic virus (EACMV-UG) and South African cassava mosaic virus (SACMV). It was revealed that mixed infections were prevailing in the analyzed materials. Most of the samples submitted to this analysis were found to be co-infected by three different begomoviruses (ACMV + EACMV + EACMV-UG). The so revealed mixed infections could explain the high severity of CMD symptoms noticed on cassava in the region of Bujumbura while the diversity within the CMD causal agents illustrates the importance to take this parameter into consideration for a successful use of plant genetic resistance to control the disease.     

Occurrence and distribution of lettuce mosaic disease in Tehran province from Iran

Lettuce mosaic virus (LMV) Cucumber mosaic virus (CMV) and Tomato spotted wilt virus (TSWV) were identified in fields of Tehran province. In this study 452 leaf samples were collected from the fields throughout the Tehran province during 2002 and 2003. Distribution of Lettuce mosaic virus (LMV), Cucumber mosaic virus (CMV), Tomato spotted wilt virus (TSWV)and Arabis mosaic virus (ArMV) was determined with DAS-ELISA. Percentage of single Infection to LMV. CMV or TSWV was 20.58, 15.93 and 9.96% respectively. Also 15.28% of samples were co- infected with LMV+CMV, 8.19% with LMV+TSMV and 7.74% with CMV+TSWV. 4.65% of samples were Infected to all of these three viruses. LMV was found in 48.69%, CMV in 43.59% and TSWV in 30.54% of samples totally. Therefore LMV is major dominant agent of lettuce mosaic disease in Tehran province. This is the first report of occurrence of TSWV on lettuce in Iran and first report of CMV and LMV in Tehran province.     

Transgenic tobacco plants expressing a coat protein gene of tobacco mosaic virus are resistant to some other tobamoviruses

Transgenic tobacco plants expressing the coat protein (CP) gene of tobacco mosaic virus were tested for resistance against infection by five other tobamoviruses sharing 45-82% homology in CP amino acid sequence with the CP of tobacco mosaic virus. The transgenic plants (CP+) showed significant delays in systemic disease development after inoculation with tomato mosaic virus or tobacco mild green mosaic virus compared to the control (CP-) plants, but showed no resistance against infection by ribgrass mosaic virus. On a transgenic local lesion host, the CP+ plants showed greatly reduced numbers of necrotic lesions compared to the CP- plants after inoculation with tomato mosaic virus, pepper mild mottle virus, tobacco mild green mosaic virus, and Odontoglossum ringspot virus but not ribgrass mosaic virus. The implications of these results are discussed in relation to the possible mechanism(s) of CP-mediated protection.     

Studies on rose mosaic disease in field-grown roses produced in the United Kingdom

Arabis mosaic virus (AMV) and prunus necrotic ringspot virus (PNRSV), separately or together, caused in field-grown roses the range of symptoms recognised as rose mosaic disease. PNRSV infection alone generally induced chlorotic line patterns, ring-spots or mottles in the leaves at some time during the growing season; AMV plus PNRSV normally caused chlorotic vein-banding. However, during prolonged periods of high temperatures (c. 21 °C or more) vein banding occurred in some roses infected only with PNRSV. Isolates of PNRSV from rose had particles which were similar in shape, protein mol. wt, density and sedimentation coefficients to previously described isolates of PNRSV from cherry, plum and rose; all were cherry serotypes. In graft-inoculated roses, apple serotypes of PNRSV induced stunting and chlorosis, puckering and distortion of leaves, which closely resembled symptoms associated with rose mosaic in the USA and chlorotic mottle rose mosaic in New Zealand. To avoid possible confusion in using the name rose mosaic it is suggested that the virus(es) present in roses should be named.     

山东烟台小麦土传病毒病由小麦黄花叶病毒和土传小麦花叶病毒相关病毒复合侵染所致

在山东省烟台地区的小麦上发生一种由土壤中禾谷多粘菌Polymyxa graminis传播的病毒病,感病小麦植株表现矮化褪绿和花叶症状.我们于1997年4月从病区采集感病小麦植株,进行了病毒种类鉴定.直接电镜观察发现有二种病毒粒子,一种粒子呈棒状,占大多数,其长度约为300nm和150nm; 另一种粒子呈线状,数量较少,长度为500nm～700nm.免疫电镜结果表明,棒状病毒粒子仅与土传小麦花叶病毒(soil-borne wheat mosaic virus, SBWMV)抗血清反应,而不与小麦黄花叶病毒(wheat yellow mosaic virus,WYMV)抗血清和小麦梭条斑花叶病毒(wheat spindle streat mosaic virus,WSSMV)抗血清反应;反之,线状病毒仅与WYMV、WSSMV抗血清反应,而不与SBWMV抗血清反应.用WYMV和SBWMV两种抗血清同时进行修饰时,线状病毒粒子和棒状病毒粒子均发生反应.     

Viruses detected in Ullucus tuberosus (Basellaceae) from Peru and Bolivia

Ullucus tuberosus (Basellaceae) plants from 12 locations in the Andean highlands of Peru and Bolivia contained complexes of either three or four viruses. Specimens from six sites in Peru contained a potexvirus, a tobamovirus, a potyvirus and a comovirus, but those from another location lacked the potexvirus. All samples from five sites in Bolivia lacked the tobamovirus. The potexvirus (PMV/U) is a strain of papaya mosaic virus differing slightly from the type strain (PMV/T) in inducing milder symptoms in some common hosts and failing to infect a few other species. It symptomlessly infected U. tuberosus, and infected 15 of 29 species from seven of nine other families. PMV/U showed a close serological relationship to PMV/T and to boussingaultia mosaic virus and a distant relationship to commelina virus X, but it is apparently unrelated to any of ten other potexviruses. The tobamovirus (TMV/U) induced symptomless or inconspicuous infection in U. tuberosus, and infected 21 of 30 species from six of eight other families. It showed a very distant serological relationship to some strains of ribgrass mosaic, tobacco mosaic and tomato mosaic viruses, but failed to react with antisera to cucumber green mottle mosaic, frangipani mosaic, odontoglossum ringspot and sunn-hemp mosaic viruses. The potyvirus, tentatively designated ullucus mosaic virus (UMV), alone in U. tuberosus induced leaf symptoms indistinguishable from the chlorotic mottling and distortion found in naturally infected plants. UMV infected 12 of 20 species from four other families, and was transmitted in the non-persistent manner by Myzus persicae. It showed a distant serological relationship to only two (bidens mottle and alstroemeria mosaic) of 25 members or possible members of the potyvirus group tested. Some hosts and properties of the comovirus are described in an accompanying paper. None of the four viruses infected potato (Solanum tuberosum) and, with the possible exception of UMV, they differed from viruses reported previously to infect three other vegetatively propagated Andean crops (Oxalis tuberosa, Arracacia xanthorrhiza and Tropaeolum tuberosum).     

Involvement of Volatile Substances in Systemic Resistance of Barley Against Erysiphe graminis f. sp. hordei Induced by Pruning of Leaves

Horsegram yellow mosaic disease was shown to be caused by a geminivirus; horsegram yellow mosaic virus (HYMV). The virus could not be transmitted by mechanical sap inoculation. Leaf dip and purified virus preparations showed geminate virus particles, measuring 15-18 * 30 nm. An antiserum for HYMV was produced and in enzyme-linked immunosorbent assay (ELISA) and immunosorbent electron microscopy (ISEM) tests HYMV was detected in leaf extracts of fieldinfected bambara groundnut, french bean, groundnut, limabean, mungbean, pigeonpea and soybean showing yellow mosaic symptoms. Bemisia tabaci fed on purified HYMV through a parafilm membrane transmitted the virus to all the hosts listed above but not to Ageratum conyzoides, okra, cassava, cowpea, Croton bonplandianus, Lab-lab purpureus, Malvastrum coromandalianum and tomato. No reaction was obtained in ELISA and ISEM tests between HYMV antibodies and extracts of plants diseased by whitefly-transmitted agents in India such as A. conyzoides yellow mosaic, okra yellow vein mosaic, C. bonplandianus, yellow vein mosaic, M. coromandalianum yellow vein mosaic, tomato leaf curl and cassava mosaic. HYMV was also not found to be related serologically to bean golden mosaic, virus.     

Specificity of the effect of sap-transmissible viruses in increasing the accumulation of luteoviruses in co-infected plants

The concentration of potato leafroll luteovirus (PLRV) (c. 1300 ng/g leaf) in singly infected Nicotiana clevelandii plants was increased up to 10-fold in plants co-infected with each of several potyviruses, or with narcissus mosaic potexvirus, carrot mottle virus or each of three tobravirus isolates. With the tobraviruses, PLRV concentration was increased equally by co-infection with either NM-type isolates (coat protein-free cultures containing RNA-1) or M-type isolates (particle-producing cultures containing RNA-1 and RNA-2). In contrast, the accumulation of PLRV was not substantially affected by co-infection with either of two nepoviruses, cucumber mosaic cucumovirus, broad bean mottle bromovirus, alfalfa mosaic virus, pea enation mosaic virus or parsnip yellow fleck virus. The specificity of these interactions between PLRV and sap-transmissible viruses was retained in tests made in Nicotiana benthamiana and when beet western yellows luteovirus was used instead of PLRV.     

Viren als Krankheitserreger bei Gemüsekulturen im Süden der Fernöstlichen Region Russlands

Im Fernen Osten Russlands werden die dort vorherrschenden Gemüsekulturen Tomate, Paprika, Eierpflanze, Zucchini, Gurke, Weiß - und Blumenkohl sowie Radies und Loba - Rettich von einer Reihe von Viruskrankheiten befallen, die ernsthafte Verluste verursachen können. Folgende Viren wurden isoliert: aus Paprika Normal-und Nekrosestämme des Tobacco mosaic virus , (TMV), aus Tomate und Eierpflanze - Stämme des Tomato mosaic virus (ToMV), aus Zucchini - das Watermelon mosaic virus (WMV), aus Paprika, Tomate, Gurke und Eierpflanze - das Cucumis mosaic virus (CMV), aus Paprika das Tobacco etch virus (TEV) und aus der Schalotte - das Onion yellow dwarf virus (OYDV). Auf Gemüsearten aus der Familie der Brassicaceae wurden das Turnip mosaic virus (TuMV), das Radish mosaic virus (RaMV) und das Cauliflower mosaic virus (CaMV) identifiziert.     

A Novel Satellite RNA of Cucumber Mosaic Virus Induces Unique Line-pattern Mosaic Symptoms in Tobacco

The CMV(YW) isolate of cucumber mosaic virus (CMV) induced unique line‐pattern mosaic symptoms in systemically infected leaves of tobacco (Nicotiana tabacum cv. Ky57). By northern hybridization analysis using cDNA to CMV(Y) satellite RNA as a probe, it was confirmed that CMV(YW) contained a satellite RNA. which was designated sat‐YW RNA; this was 388 nucleotides in length and did not have either a conserved domain that induces necrosis in tomato or chlorosis in tobacco. CMV(YW) free of sat‐YW RNA. which was isolated by the single lesion isolation method using Chenopodium amaranticolor, did not induce the unique line‐pattern mosaic symptom. Furthermore, the sat‐YW RNA‐mediated line‐pattern mosaic symptom was also induced by in vitro transcribed infectious sat‐YW RNA in tobaccos infected with either CMV(YW) or CMV(Y) genomic RNA. These results clearly demonstrated that sat‐YW RNA induces the unique line‐pattern mosaic symptom on CMV‐infected tobaccos.     

The Association of "Pathogenesis-related" Proteins with Viral Induced Necrosis in Nicotiana sylvestris

The association of “pathogenesis-related” (PR) proteins with protection from superinfection, systemic acquired resistance and production of localized necrotic lesions was examined with a system using tobacco mosaic virus (TMV) and Nicotiana sylvestris. Leaves of N. sylvestris with a mosaic from earlier inoculation with a systemically infecting strain of TMV (TMV-C) and control plants were challenged with a necrotizing strain of TMV (TMV-P), RNA of TMV-P and turnip mosaic virus (TuMV). TMV-P virions produced localized necrotic lesions only in the dark green areas of the mosaic of TMV-C infected plants. Both RNA of TMV-P and TuMV produced localized necrotic lesions in both light green and dark green areas of the mosaic of TMV-C infected plants. All three challenge inocula produced localized necrotic lesions in previously uninoculated plants. Six days after challenge inoculation proteins were extracted from separated dark green and light green mosaic leaf tissue, and leaf material from control plants. Proteins were separated by electrophoresis in a 5 % polyacrylamide spacer gel and 10 % polyacrylamide running gel. PR proteins were found in tissue where localized necrotic lesions were produced as a result of challenge inoculation, but not in tissue that was not superinfected. PR proteins were not found in light green or dark green mosaic leaf tissue as a result of TMV-C inoculation. No PR proteins were evident in protein extracts from light green tissue challenged with TMV-P, although PR proteins were produced in dark green tissue, where necrosis occurred, from the same leaves. Systemic acquired resistance (reduction in size of lesions formed by a challenge inoculation) to TuMV or RNA of TMV-P and PR protein concentration was measured at various times in light green areas of mosaic leaves where dark green areas of the mosaic leaves had been inoculated with TMV-P. No quantitative or temporal relationship between the onset of resistance and PR protein production was found. It is concluded that PR proteins are a result of pathogen induced necrosis and not significantly involved in the mechanism(s) of viral induced resistance.     

Virus diseases of garden lupin in Great Britain

Two viruses occur widely in lupins in Britain. Alfalfa mosaic virus (AMV), of which two strains were isolated, was found mainly in named Russell varieties. Lupin mottle virus (LMV), a previously undescribed strain of the bean yellow mosaic virus (BYMV) common pea mosaic virus (CPMV) complex, was found more commonly in seedling lupins. Cucumber mosaic virus (CMV) was isolated once. The AMV strains were differentiated by their reaction in Phaseolus vulgaris; they were serologically closely related. Both AMV and LMV were aphid transmitted but not transmitted in lupin seed. LMV was distantly serologically related to both BYMV and CPMV. It cross-protected against BYMV but not against CPMV and it differed from both these viruses in some host reactions. The CMV isolate from lupins was similar to type CMV. It was transmitted both mechanically and by aphid, easily from cucumber to cucumber, but with difficulty from cucumber to lupin.     

Incidence and diversity of viruses in cowpeas and weeds in the unmanaged farming systems of savanna zones in Nigeria

Fields surveys were conducted to assess the incidence of commonly known legume viruses on cowpeas and weed hosts within and around the cowpeas farms in nine locations across the three agro-ecological zones of Nigeria. Of 315 cowpea leaf samples collected and tested for eight viruses, 69.5% were found to be infected. Bean common mosaic virus-blackeye mosaic (BCMV-BlCM), genus Potyvirus had the highest incidence (70%) and was also the most prevalent (78%). Cowpea aphid-borne mosaic virus (CABMV, genus Potyvirus) had 64% as incidence, incidence of Southern bean mosaic virus (SBMV, genus Sobemovirus) was 21%. Bean pod mosaic virus (BPMV, genus Comovirus) was detected in 1% of the samples tested. Cowpea mosaic virus (CPMV, genus Comovirus) was undetected. Other viruses tested included Cowpea mottle virus (CPMoV, genus Carmovirus), Cucumber mosaic virus (CMV, genus Cucumovirus), and Cowpea mild mottle virus (CPMMV, genus Carlavirus). Multiple virus infections were detected in 68.0% of the infected cowpea leaf samples. The combination of BCMV-BlCM and CABMV was the most common, occurring in 76.4% of all samples. Virus incidence in weeds around the cowpea plots was 2.5% (9 out of 356) whereas 1.5% (5 out of 332) of the weeds collected within the cowpea plots were infected. Some of the weeds infected were Chromoleana odorata, Centrosema sp., Thithonia diversifolia and Talinum triangulare.     

SAP-TRANSMISSIBLE MOSAIC DISEASES OF SOLANACEOUS CROPS IN TRINIDAD

Four sap-transmissible viruses were isolated from cultivated Solanaceae in Trinidad: (1) tobacco mosaic virus, from tobacco, tomato and sweet pepper; (2) cucumber mosaic virus, from tobacco and petunia; (3) 'pepper vein-banding virus', probably related to pepper mosaic viruses in Puerto Rico and Brazil, from peppers and tobacco; (4) 'egg-plant mosaic virus', possibly related to the tobacco ring-spot virus, from egg-plant and tomato. Pepper vein-banding virus causes leaf-crinkling and vein-banding in Physalis floridana , petunia, various Nicotiana spp. and most peppers; the Large Bell Hot pepper is killed; tomato and egg-plant are immune. Egg-plant mosaic virus produces mosaic, ring-spotting, or both, on different solanaceous species. It also gives local and systemic ring-spotting on Chenopodium hybridum and necrotic local lesions on the primary leaves of cowpea (var. Black-eye); cucumber is a symptomless carrier. Only cucumber mosaic virus was found naturally infecting non-solanaceous hosts, cucumber and certain common wild plants.
The thermal inactivation point of pepper vein-banding virus is 62° C, its dilution end-point 2×10^-5 and its longevity in vitro 6 day s at 23–30° C.; corresponding values for egg-plant mosaic virus are 78° C., 10^-6 and over 3 weeks. Aphisgossypii transmits cucumber mosaic and pepper vein-banding, but not egg-plant mosaic, of which Epitrix sp. is an occasional vector. Tobacco mosaic, as elsewhere, probably has no regular insect vectors in Trinidad.     

Comparative epitope profiles of the particle proteins of whitefly-transmitted geminiviruses from nine crop legumes in India

Geminiviruses associated with yellow or golden mosaic diseases of legume crops in two regions of India were compared by testing their reactivity with 27 monoclonal antibodies (MAbs) prepared to the particles of African cassava mosaic (ACMV) or Indian cassava mosaic (ICMV) viruses. The viruses fell into two main groups. Group 1 comprised isolates of dolichos yellow mosaic virus; these reacted with three or four ACMV MAbs and four ICMV MAbs. Group 2 comprised isolates of horsegram yellow mosaic virus, together with isolates from blackgram, cowpea, French bean, pigeonpea, soybean, Indigofera hirsuta and probably also isolates from mungbean. These reacted with three or four ACMV MAbs but with few or no ICMV MAbs. Isolates within each group differed slightly in epitope profile, depending on the source species (Group 2) or geographical origin (Groups 1 and 2). Isolates from lima bean resembled those in Group 2 but had some antigenic differences, and their status is uncertain. The poor detectability of geminivirus isolates in mungbean may reflect a low virus concentration in this species.     

Evolutionary relationship of alfalfa mosaic virus with cucumber mosaic virus and brome mosaic virus

The amino acid sequences of the non-structural protein (molecular weight 35,000; 3a protein) from three plant viruses — cucumber mosaic, brome mosaic and alfalfa mosaic have been systematically compared using the partial genomic sequences for these three viruses already available. The 3a protein of cucumber mosaic virus has an amino acid sequence homology of 33.7% with the corresponding protein of brome mosaic virus. A similar protein from alfalfa mosaic virus has a homology of 18.2% and 14.2% with the protein from brome mosaic virus and cucumber mosaic virus, respectively. These results suggest that the three plant viruses are evolutionarily related, although, the evolutionary distance between alfalfa mosaic virus and cucumber mosaic virus or brome mosaic virus is much larger than the corresponding distance between the latter two viruses.