Groundnut Rosette Virus Research Articles

The satellite RNAs associated with the groundnut rosette disease complex and pea enation mosaic virus: sequence similarities and ability of each other's helper virus to support their replication.

Pea enation mosaic virus (PEMV) and the causal agents of groundnut rosette disease are diverse examples of disease complexes involving two RNA species, one of which is related to the genomes of luteoviruses and the other to those of umbraviruses. In both complexes, these viral RNA components may be supplemented with satellite RNAs that are dependent on the umbravirus component for replication and systemic movement, and on the luteovirus component for encapsidation and vector transmission. Sequence analysis identified regions of similarity between the satellites of groundnut rosette virus (GRV) and PEMV, particularly at the 5' and 3' termini and around duplicate sequence repeats present in each satellite RNA. The umbravirus GRV and the umbravirus-like PEMV RNA-2 were each able to support the replication and systemic spread of homologous and heterologous satellites. The presence of the PEMV satellite in infections with GRV had no effect on symptom expression in Nicotiana spp. or in Arachis hypogaea. Likewise, in Pisum sativum, the GRV satellite had no effect on the symptoms induced by PEMV. However, the intense yellow blotch symptoms induced in Nicotiana benthamiana by the YB3 GRV satellite in conjunction with GRV were also manifested when PEMV was the helper. Although PEMV RNA-1 was capable of supporting the encapsidation and aphid transmission of the GRV satellite, no evidence was obtained that the essential role of the GRV satellite in the aphid transmission of GRV could be supplied by the PEMV satellite. These data further strengthen the hypothesis of an evolutionary relationship between PEMV and the luteovirus-umbravirus complexes.

Detection of groundnut rosette umbravirus infections with radioactive and non‐radioactive probes to its satellite RNA

SummaryA cloned cDNA copy of the satellite RNA of groundnut rosette virus (GRV), labelled with either 32P or digoxigenin, was used as a probe to detect the satellite RNA in infected leaves. The test was successfully applied to N. benthamiana and to groundnuts, infected with isolates of GRV from East and West Africa and with isolates which cause different types of symptom in groundnuts, including one which is almost symptomless. Although the probe did not react with extracts from plants infected with GRV isolates from which the satellite RNA had been artificially eliminated, all naturally occurring GRV isolates contain the satellite RNA. The test therefore provides a reliable indicator of infection by GRV.

Mechanical Inoculation Procedure to Screen for Resistance to Groundnut Rosette Virus in Peanut1

Abstract A mechanical inoculation procedure was developed for screening peanut plants for resistance to groundnut rosette virus (GRV) (green strain). A single inoculation resulted in 100% infection of plants of susceptible genotypes and about 2% of resistant plants which could be distinguished from susceptible ones on the basis of delayed time of first appearance of symptoms and disease severity. The procedure utilized highly infectious inoculum. The consistency and reliability of achieving infection should make the procedure particularly effective for inheritance of resistance studies and breeding programs.

An insect, agronomic and sociological survey of groundnut fields in southern Africa

An intensive survey of the insects in groundnut fields in Malawi, Zambia and Zimbabwe was carried out in the 1986–1987 production season. Less intensive surveys were also made in Tanzania and Botswana. Agronomic and socio-economic details of approximately 100 farms were collected simultaneously. The insect survey concentrated on soil insects. White grubs (scarabeid larvae) were the predominant taxon and were likely to be causing considerable reductions in crop yield. About 40 species of the former were collected. They were followed in order of importance by termites. Pod borers (elaterids, tenebrionids, doryline ants and millipedes) were generally present but rarely at sufficient densities to warrant concern. Hilda patruelis was encountered in high densities when crops had been sown too early. White grubs were most likely to be encountered in areas of intensive agriculture, where rainfall exceeded 1000 mm year −1 and where soils were sandy or loamy. termite damage was associated with drought, mainly at the end of the growing season. It was especially severe in Botswana. Insect pest management options should be restricted to high risk areas. Insecticides should be applied only to the preceding maize crop because of the risk of seed-oil contamination. Experimentation on other management options for the soil insects may demonstrate the benefits of fallowing and growing economically viable cleansing crops. Foliage feeders were apparently of no economic importance except where insecticides had been applied (entirely a research station activity). Aphis craccivora, the vector of groundnut rosette virus (GRV), was apparently controlled by natural processes. The low incidence of GRV in the region may be caused by early (and synchronous) sowing. The economic survey indicated that groundnut crops generated cash to a level that would enable farmers to purchase the inputs needed to give future groundnut crops a considerable boost in yield.

Sequences of 10 Variants of the Satellite-like RNA-3 of Groundnut Rosette Virus

Ten cDNA clones, representing the satellite-like RNA-3 associated with five different isolates of groundnut rosette virus, were prepared and sequenced. The sequences are at least 87% identical, but differences associated both with symptom differences and with geographical origin were found. The sequences contain up to five potential open reading frames (ORFs), of which three are in the strand that is most abundant in infected plants and two are in the complementary strand. Only one of these ORFs is present in all 10 sequences. Neither the sequence of RNA-3 nor that of its potential translation products had significant similarities to sequences in the databases.

Inheritance of Resistance in Peanut to Mixed Infections of Groundnut Rosette Virus (GRV) and Groundnut Rosette Assistor Virus and a Single Infection of GRV

Inheritance of resistance to the green form of groundnut rosette was studied in two ways—aphid inoculation in the field with a mixed culture of groundnut rosette virus (GRV) (plus its satellite RNA) and groundnut rosette assistor virus (GRAV) and mechanical inoculation in the greenhouse with GRV (plus its satellite RNA). Crosses were made with two resistant and six susceptible genotypes in a diallel test. In most crosses, the resistance was conditioned by two recessive genes. Furthermore, results were similar both with mixed infections and the single GRV infection, thus providing direct evidence that genetic control of resistance is to GRV and not to GRAV. In the RMP 12 × M1204.78I cross (and its reciprocal), F2 progeny segregated 1:3 susceptible/resistant. Mechanical inoculation with GRV provided an acceptable and rapid procedure to screen segregating populations for resistance to the virus

A variant of the satellite RNA of groundnut rosette virus that induces brilliant yellow blotch mosaic symptoms in Nicotiana benthamiana

SUMMARYSome Malawian cultures of groundnut rosette virus (GRV) give rise to variants that, although still causing symptoms of the chlorotic type of rosette in groundnut, induce brilliant yellow blotch mosaic symptoms, instead of the usual veinal chlorosis and mild mottle, in Nicotiana benthamiana. One such isolate (YB) induced the formation in infected plants of a 0.9 kbp dsRNA having extensive sequence homology with molecules of similar size in other naturally occurring isolates of GRV. These dsRNA molecules were shown to be double‐stranded forms of single‐stranded satellite RNA molecules. Experiments in which the satellite was removed from and restored to isolate YB, or exchanged with those from other GRV isolates, showed that it carries the determinant for yellow blotch mosaic symptoms. Plants inoculated with the 0.9 kbp dsRNA (denatured or undenatured) developed yellow blotch mosaic even when the satellite‐free GRV helper was not inoculated until 11 days later. The satellite RNA is therefore a very stable molecule. Prior infection of N. benthamiana with a GRV isolate containing a normal form of the satellite protected against expression of yellow blotch mosaic symptoms when the plants were later inoculated with isolate YB, whereas prior infection with satellite‐free isolates did not. This provides a simple method of determining whether a GRV isolate has an associated satellite RNA. The YB satellite seems to be a newly recognised variant additional to those known to cause the chlorotic, green and other forms of groundnut rosette disease.

Disease Reactions and Yield Performance of Peanut Genotypes Grown Under Groundnut Rosette and Rosette-Free Field Environments

Experimental field conditions were established to determine the effect of groundnut green rosette (caused by groundnut rosette virus [GRV and its satellite RNA] and groundnut rosette assistor virus [GRAV]) on susceptible and resistant peanut genotypes. Test genotypes were planted in alternate rows with susceptible genotype F 452.4 in which rosette-diseased plants, infested with viruliferous aphids, were transplanted every 1.5 m. When disease incidence was high (90–100%) but severity was moderate (measured on rating scale of 1–5) in susceptible genotypes in 1988, only 9–10% of the resistant plants of RMP 12 and RG 1 showed very mild mottle. In 1989, when incidence in susceptible plants was 100% and disease was very severe, about 87% of the resistant plants showed symptoms but only 2–5% had severe symptoms. In the rosette environment, seed yield was 33 times higher in resistant genotypes than in susceptible ones, and yields in general were comparable in the two groups under rosette disease-free conditions. We consider RMP 12 and RG 1 to be highly resistant to GRV and its satellite but not to GRAV, which causes no leaf symptoms by itself but is essential for aphid transmission of GRV and its satellite

Monoclonal antibodies to double-stranded RNA as probes of RNA structure in crude nucleic acid extracts

We describe four monoclonal antibodies (MAB) which specifically recognize double-stranded RNA (dsRNA) together with their use in new methods for detecting and characterizing dsRNA in unfractionated nucleic acid extracts. The specificity of the antibodies was analyzed using a panel of 27 different synthetic and naturally occurring nucleic acids. All four antibodies reacted in a highly specific manner with long dsRNA helices, irrespective of their sequence; no binding to single-stranded RNA homopolymers or to DNA or RNA-DNA hybrids was observed. The apparent affinity of the antibodies to short (less than or equal to 11 bp) RNA helices was very low in all test systems used: only background levels of binding were obtained on single-stranded RNA species which contain double-helical secondary structures (e.g. rRNA, tRNA, viroid RNA). A sandwich ELISA and a dsRNA-immunoblotting procedure have been established which allow detection and characterization of dsRNA by MAB even in the presence of a large excess of other nucleic acids. In combination with temperature-gradient gelelectrophoresis (TGGE) not only the molecular weights but also the highly characteristic Tm-values of conformational transitions of individual dsRNA species could be determined by immunoblotting. An example of the general use of these methods for the detection of plant virus infections is demonstrated with groundnut rosette virus (GRV) dsRNAs. We were able to estimate the dsRNA content of infected leaves, identify the dsRNA species present in crude extracts and to determine the Tm- values of GRV dsRNA-3.

Inheritance of resistance to groundnut rosette virus in groundnut (Arachis hypogaea L.)

SummaryA method of field screening groundnut seedlings for resistance to groundnut rosette virus (GRV), by means of which over 97% incidence was induced in rows of susceptible test plants, was developed at Chitedze Research Station in Malawi. Two GRV‐resistant Virginia cultivars (RG 1 and RMP 40) were crossed with three susceptible cultivars, one from each of the Spanish (JL 24), Valencia (ICGM 48) and Virginia (Mani Pintar) botanical groups. Twelve F1 reciprocal crosses and their F2 and backcross generations were produced and the material screened in nurseries in 1985/86 and 1986/87. Seedlings raised from plants which did not become infected in the field were inoculated in the glasshouse in order to eliminate susceptible escapees.The numbers of diseased and healthy individuals in each population were subjected to χ2 tests. In the majority of the F2 populations a good fit was obtained for a ratio of one resistant to 15 susceptible plants, a ratio to be expected if resistance to GRV were determined by a pair of independent complementary recessive genes. This was further supported by data from backcross generations.

The nature of the resistance in groundnut to rosette disease

SUMMARYGroundnut rosette disease is caused by a complex of three agents, groundnut rosette virus (GRV) and its satellite RNA, and groundnut rosette assistor virus (GRAV); the satellite RNA is mainly responsible for the disease symptoms. Groundnut genotypes possessing resistance to rosette disease were shown to be highly resistant (though not immune) to GRV and therefore to its satellite RNA, but were fully susceptible to GRAV.

Dependence of groundnut rosette virus on its satellite RNA as well as on groundnut rosette assistor luteovirus for transmission by Aphis craccivora

Transmission of groundnut rosette virus (GRV) by Aphis craccivora is known to depend on the additional presence in the source plants of a luteovirus, groundnut rosette assistor virus (GRAV). Naturally occurring isolates of GRV contain a satellite RNA which is the main cause of rosette symptoms in groundnut, different variants of the satellite being responsible for the green and chlorotic forms of rosette. In extensive glasshouse tests, GRAV-dependent transmission of GRV by A. craccivora occurred only from groundnut plants infected with satellite-containing isolates of GRV. This was true whether the GRV isolates were from groundnut plants from Nigeria or Malawi with either the green or chlorotic forms of rosette and whether they contained homologous or heterologous satellites. Aphid transmission of GRV therefore depends not only on the presence of GRAV but also on that of the GRV satellite RNA. This probably explains why satellite-free isolates of GRV have not been found in nature. This is the first report of satellite RNA mediating aphid transmission of a plant virus.

Different variants of the satellite RNA of groundnut rosette virus are responsible for the chlorotic and green forms of groundnut rosette disease*

SUMMARYGroundnut plants with symptoms of rosette disease contain groundnut rosette virus (GRV), but GRV is transmitted by Aphis craccivora only from plants that also contain groundnut rosette assistor virus (GRAV). Two main forms of rosette disease are recognised, ‘chlorotic rosette’ and ‘green rosette’. GRV cultures invariably possess a satellite RNA and this is the major cause of rosette symptoms: satellite‐free isolates derived from GRV cultures from Nigerian plants with chlorotic or green rosette, or from Malawian plants with chlorotic rosette, induced no symptoms, or only transient mild mottle or interveinal yellowing, in groundnut. When the satellite RNA species from GRV cultures from Nigerian green or Malawian chlorotic rosette were reintroduced into the three satellite‐free isolates in homologous and heterologous combinations, the ability to induce rosette symptoms was restored and the type of rosette induced was that of the cultures from which the satellite RNA was derived. Thus different forms of the satellite are responsible for the different forms of rosette disease. Other forms of the satellite induce only mild chlorosis or mottle symptoms in groundnut. Individual plants may contain more than one form of the satellite, and variations in their relative predominance are suggested to account for the variable symptoms (ranging from overall yellowing to mosaic) seen in some plants graft‐inoculated with chlorotic rosette.

A Satellite RNA of Groundnut Rosette Virus that Is Largely Responsible for Symptoms of Groundnut Rosette Disease

Summary Groundnut (Arachis hypogaea) plants with rosette disease contain a manually transmissible virus, groundnut rosette virus (GRV), which depends on a luteovirus, groundnut rosette assistor virus (GRAV), for transmission by the aphid Aphis craccivora. No virus-like particles have been reported for GRV but infected plants yield infective ssRNA. Infected leaves also contain dsRNA with prominent electrophoretic species of 4.6 kbp (dsRNA-1) and 1.3 kbp (dsRNA-2), a very abundant species of 900 bp (dsRNA-3), and numerous minor species of intermediate mobility. In studies with GRV(C), an isolate from groundnut plants with a chlorotic form of rosette, cDNA to dsRNA-1 reacted with dsRNA-1 and dsRNA-2 but not with dsRNA-3 or any of the minor dsRNA species. In contrast, cDNA to dsRNA-3 reacted with dsRNA-3 and several of the minor dsRNA species but reacted only weakly or not at all with dsRNA-1 or dsRNA-2. An isolate lacking dsRNA-3 (isolate G96) was derived from GRV(C) by passage through Gomphrena globosa. When dsRNA-3 recovered from agarose gels was melted and inoculated to Nicotiana benthamiana plants, it was not infective on its own but multiplied in plants that were also infected with G96. Similar results were obtained with sucrose density gradient fractions containing RNA molecules of the size expected for ssRNA-3. These results show that dsRNA-3 represents a satellite RNA. Addition of dsRNA-3 to the G96 culture resulted in a slight amelioration of symptoms in N. benthamiana and N. clevelandii. However, only cultures containing RNA-3 induced rosette symptoms in groundnut, though the symptoms were intensified by further addition of GRAV. The results show that the satellite RNA is largely responsible for rosette disease symptoms in groundnut.

Properties and partial purification of infective material from plants containing groundnut rosette virus*

SUMMARYGroundnut plants with chlorotic rosette disease contain a manually transmissible virus, groundnut rosette (GRV), which is also transmitted in the persistent (circulative) manner by aphids (Aphis craccivora), but only from plants that are co‐infected with a manually non‐transmissible luteovirus, groundnut rosette assistor virus (GRAV). Strains of GRV from plants with chlorotic or green forms of rosette are called GRV(C) and GRV(G) respectively. An isolate of GRV(C) from Nigeria remained infective in Nicotiana clevelandii leaf extracts for 1 day at room temperature and for 15 days at 4d̀C, but lost infectivity after 1 day at ‐20d̀C or after dilution to 10‐‐4. Its infectivity and longevity in vitro were not altered by addition of 1 mg/litre bentonite to the extraction buffer. Infectivity in leaf extracts was abolished by treatment with 50% (v/v) ether, 10% (v/v) chloroform or 8% (v/v) n‐butanol, but not by treatment for 30 min with RNase A at up to 100 ng/ml. In attempts to purify GRV(C), nearly all the infectivity from N. clevelandii extracts was found in the pellets from centrifugation at 65 000 g for 1. 5 h; infectivity also occurred in a cell membrane fraction that collected at the top of a 30% sucrose ‘cushion’ containing 4% polyethylene glycol and 0.2 M NaCI. However, no virus‐like particles were found in either type of preparation by electron microscopy.Nucleic acid preparations made directly from GRV(C)‐infected N. clevelandii leaves were very infective; this infectivity was totally inactivated by treatment for 30 min with RNase A at 10 ng/ml in buffers of both low and high ionic strength and was therefore attributed to ssRNA. When nucleic acid preparations were electrophoresed in gels no virus‐specific bands were visible but the position of the infectivity indicated that the infective ssRNA has an apparent mol. wt of c. 1.55 × 106. A similar mol. wt was indicated by the rate of sedimentation of the infective ssRNA in sucrose gradients. Preparations of dsRNA made from GRV(C)‐infected N. clevelandii leaves contained a species of mol. wt c. 3.0 × 106; in addition some dsRNA preparations contained an abundant component of mol. wt c. 0.6 × 106 together with several other components of intermediate mol. wt. Similar patterns of bands were observed in dsRNA preparations made from Nigerian‐grown groundnut material infected with GRV(C) alone, or with GRV(C) + GRAV, or with GRV(G) + GRAV.The properties of GRV closely resemble those of two other viruses that depend on luteoviruses for transmission by aphids, carrot mottle virus and lettuce speckles mottle virus.

Viruses associated with chlorotic rosette and green rosette diseases of groundnut in Nigeria*

SUMMARYGroundnut (Arachis hypogaea) plants from Nigeria with chlorotic rosette disease contained a manually transmissible virus, considered to be a strain of groundnut rosette virus (GRV(C)). GRV(C) infected nine out of 32 species in three out of nine families. It caused local lesions without systemic infection in Chenopodium amaranticolor, C. murale and C. quinoa, and systemic symptoms in Glycine max, Nicotiana benthamiana, N. clevelandii and Phaseolus vulgaris as well as in groundnut. Some ‘rosette‐resistant’ groundnut lines were also infected. GRV(C) was transmitted by Aphis craccivora, but only from groundnut plants that were also infected with an aphid‐transmissible second virus, which was not manually transmissible and was considered to be groundnut rosette assistor virus (GRAV). Plants infected with GRAV contained isometric particles c. 25 nm in diameter which were detectable by immunosorbent electron microscopy on grids coated with antisera to several luteoviruses, especially with antisera to bean leaf roll, potato leafroll and beet western yellows viruses. No virus‐like particles were observed in extracts from plants infected with GRV(C) alone.A single groundnut plant obtained from Nigeria with symptoms of green rosette contained luteovirus particles, presumed to be of GRAV, and yielded a manually transmissible virus that induced symptoms similar to those of GRV(C) in C. amaranticolor but gave only mild or symptomless infection of N. benthamiana and N. clevelandii. It was considered to be a strain of GRV and designated GRV(G).

Detection of a Luteovirus in Groundnut Rosette Diseased Groundnuts (Arachis hypogaea) by Enzyme‐linked Immunosorbent Assay and Immunoelectron Microscopy

AbstractIn groundnut rosette diseased groundnut plants collected near Zaria, Nigeria, a luteovirus was detected by ELISA and ISEM. In ELISA only beet western yellows virus antiserum reacted, while in ISEM luteovirus particles were trapped by antisera beet western yellows virus, potato leafroll virus, pea leafroll virus and barley yellow dwarf virus. The data are in agreement with the interpretation that the assistor of groundnut rosette virus is possibly a member of the luteovirus group.

Mechanical and Aphid Transmission of an Ivory Coast Strain of Groundnut Rosette Virus

Journal of PhytopathologyVolume 99, Issue 4 p. 318-326 Mechanical and Aphid Transmission of an Ivory Coast Strain of Groundnut Rosette Virus J. Dubern, Corresponding Author J. Dubern Virology Laboratory, Adiopodoumé Research Station, Office de la Recherche Scientifique et Technique, Outre-Mer, Abidjan, Ivory CoastAuthor's address: Dr. J. Dubern, Laboratoire de Virologie-Bactériologie des Plantes, Centre O.R.S.T.O.M. de Dakar-Hann, BP 1386 Dakar (Senegal).Search for more papers by this author J. Dubern, Corresponding Author J. Dubern Virology Laboratory, Adiopodoumé Research Station, Office de la Recherche Scientifique et Technique, Outre-Mer, Abidjan, Ivory CoastAuthor's address: Dr. J. Dubern, Laboratoire de Virologie-Bactériologie des Plantes, Centre O.R.S.T.O.M. de Dakar-Hann, BP 1386 Dakar (Senegal).Search for more papers by this author First published: December 1980 https://doi.org/10.1111/j.1439-0434.1980.tb03793.xCitations: 14AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume99, Issue4December 1980Pages 318-326 RelatedInformation

Effects of intersowing with beans on the spread of groundnut rosette virus by Aphis craccivora Koch (Hemiptera, Aphididae) in Malawi

AbstractIn two trials, at Chitedze, Malawi, in 1966–1967, the spread of rosette virus disease in groundnuts (Arachis hypogaea) intersown with field beans (Phaseolus vulgaris) was less than the spread in groundnut monocultures comprising plant populations equivalent to the number of groundnut plants and to the total number of plants in the intersown crop. In one trial, numbers of early rosette transmissions were related to numbers of alate Aphis craccivora Koch, the vector of the virus, found on groundnut plants. Immigrant alate A. craccivora settling on the intersown crop were trapped by the hooked epidermal hairs of the bean plants and the observed reduction of rosette infection in the intersown crop was attributed to this effect. Inter-sowing with beans is considered less effective than early-sown, high-density monoculture as a method of reducing groundnut rosette infections and yields of groundnuts from inter-sown crops may be lower than those obtained from high-density monoculture.

Insecticides for the Control of the Spread of Groundnut Rosette Disease in Uganda

Abstract Trials described show that control of the secondary spread of groundnut rosette virus, which is transmitted by Aphis craccivora Koch, is possible with insecticides. In six trials carried out in the period 1965–1970 insecticides tested included dimethoate, phosphamidon and dicrotophos as emulsion concentrates and ulv formulations, menazon as a wettable powder, endosulfan and phenthoate as an emulsion concentrate and aldicarb as a granular formulation. Menazon, at a rate of 294 g a.i./ha applied four times at ten day intervals starting ten days from the germination (emergence) of the crop, was the most efficient insecticide overall in reducing rosette attack. In two trials it was shown to be very effective at rates of 196 and 147 g a.i./ha. Endosulfan and dimethoate and to a lesser extent phosphamidon were also successful as emulsion concentrates and in the instance of dimethoate and phosphamidon as ulv's. Dicrotophos was promising in the two trials in which it was used, but phenthoate was not. Aldicarb, used as a side dressing, was inadequately tested. Ulv application was quick, simple and efficient and has much to recommend it in Uganda conditions. Insecticides significantly reduced the percentage plants attacked in growth up to harvest. There were improvements in kernel quality, shelling percentage and yield. It was concluded that in most seasons even on well grown and well tended crops spraying was worthwhile.