Beet Curly Top Virus Research Articles

Geminivirus coat protein gene replacement alters insect specificity

Chimeric clones have been constructed in which the coat protein encoded by DNA A of the bipartite genome of the geminivirus African cassava mosaic virus (ACMV) has been replaced by that of beet curly top virus (BCTV). Constructs containing the coding region inserted in either orientation were infectious when co-inoculated with ACMV DNA B onto Nicotiana benthamiana, producing symptoms typical of ACMV infection. The onset of symptom production was delayed relative to plants inoculated with parental ACMV clones and remission of symptoms was observed. When inserted in the correct orientation for expression from the ACMV coat protein promoter, the BCTV gene was expressed in plants and the coat protein synthesized encapsidated ssDNA of both ACMV genomic components. The BCTV leafhopper vector, Circulifer tenellus (Baker), transmitted both BCTV and the chimeric virus but not ACMV when injected with virus preparations and transferred to N. benthamiana seedlings. The results show that the specificity of leafhopper transmission from insect to plant resides with the coat protein.

Partial Characterization and Serological Analysis of Pseudo-Curly Top Virus

(...) Indirect ELISA tests showed a relationship between PCTV and beet curly top virus. Nucleic acid extracted from partially purified PCTV virions was digested by DNase I but not by RNase A

The coat protein of beet curly top virus is essential for infectivity

We have applied the procedure of Agrobacterium-mediated inoculation to develop a simple, efficient, and reproducible assay for the infectivity of the leafhopper-transmitted geminivirus, beet curly top virus (BCTV). This assay system was used to show that a coat protein mutant of BCTV is not infectious, but could be complemented by coagroinoculation with a second mutant bearing a lethal mutation in the complementary-sense open reading frame, C1. Furthermore, the coat protein mutant retained the ability to replicate and to produce both ssDNA and dsDNA when electroporated into Nicodana tabacum protoplasts. We conclude that the coat protein of BCTV is essential for spread of the virus. The results are discussed in the light of results with coat protein mutants of other gem iniviruses

Production of Monoclonal Antibodies to African Cassava Mosaic Virus and Differences in Their Reactivities with Other Whitefly-transmitted Geminiviruses

Summary A panel of murine monoclonal antibodies (MAbs), selected by indirect ELISA, was prepared to an isolate (ACMV-JI) of the type strain of African cassava mosaic virus. Of the ten MAbs purified from ascitic fluids, four out of the five tested gave stronger reactions with ACMV-JI in double antibody sandwich ELISA (DAS-ELISA) than did rabbit polyclonal antibody. Six of the ten MAbs gave a precipitin reaction in immunodiffusion tests and nine trapped ACMV-JI particles in immunosorbent electron microscopy. Rabbit polyclonal antibody to ACMV reacted in DAS-ELISA not only with ACMV-JI and the Kenya coast strain of ACMV (ACMV-C) but also with five other geminiviruses known or suspected to have the whitefly Bemisia tabaci as a vector, though not with three geminiviruses that have leafhopper or unknown vectors. Of the ten MAbs studied in detail, four did not react with ACMV-C in indirect ELISA and only two reacted strongly. This supports other evidence that ACMV-C is a distinctive strain of ACMV and not merely a minor variant. The other whitefly-transmitted geminiviruses (bean golden mosaic, euphorbia mosaic, mung bean yellow mosaic and tomato golden mosaic viruses) and Australian tomato leaf curl virus reacted with two to five MAbs but each virus had a different pattern of reactivity. In contrast, solanum apical leaf curling virus, and the leafhopper-transmitted beet curly top and maize streak viruses, did not react with any of the MAbs. The results of competitive binding tests, when combined with the patterns of reaction of individual MAbs with different viruses, indicated that the MAbs were specific for nine distinct epitopes. Two MAbs reacted with all five whitefly-transmitted viruses, suggesting that the epitopes detected by these MAbs may be important for transmission by B. tabaci. Individual MAbs seem suitable for detecting and identifying ACMV, for distinguishing between ACMV-JI and ACMV-C, and for quantitative assays of other whitefly-transmitted geminiviruses.

The nucleotide sequence of an infectious clone of the geminivirus beet curly top virus

A number of infectious clones of a Californian isolate of the leafhopper-transmitted geminivirus beet curly top virus (BCTV) have been constructed from virus-specific double-stranded DNA isolated from infected Beta vulgaris and used to demonstrate a single component genome. The nucleotide sequence of one infectious clone has been determined (2993 nucleotides). Comparison with other geminiviruses has shown that the organisation of the genome closely resembles DNA 1 of the whitefly-transmitted members. The four conserved coding regions of DNA 1 have highly homologous counterparts in BCTV with the exception of the putative coat protein which is more closely related to those of the leafhopper-transmitted geminiviruses suggesting a strong interrelationship between coat protein and insect vector. A BCTV component equivalent to DNA 2 is not required for virus infection or transmission and has not been isolated from infected plants.

Serological Relationships and Genome Homologies among Geminiviruses

SUMMARY In immunosorbent electron microscopy (ISEM) tests, strong relationships were detected between five whitefly-transmitted geminiviruses: African cassava mosaic (ACMV), bean golden mosaic, euphorbia mosaic, squash leaf curl and tomato golden mosaic. Among five leafhopper-transmitted geminiviruses, beet curly top and tobacco yellow dwarf viruses were distantly related but no relationship was detected between either chloris striate mosaic, maize streak or wheat dwarf viruses and any of the other four. No relationship was detected between any whitefly-transmitted and any leafhopper-transmitted virus. A similar pattern of relationships was found by spot hybridization experiments in which extracts from infected leaves were tested with probes for ACMV DNA-1 or DNA-2. Imperfect nucleotide sequence homologies were found between ACMV DNA-1, which contains the particle protein gene, and the DNA of five other whitefly-transmitted viruses: bean golden mosaic, tomato golden mosaic, tobacco leaf curl, tomato leaf curl and tomato yellow leaf curl, the last three of which are not sap-transmissible. Thus, relationships were established between sap-transmissible and sap non-transmissible geminiviruses. No homologies were detected with a full-length probe for ACMV DNA-2. Extracts from plants infected with three leafhopper-transmitted viruses (beet curly top, maize streak and wheat dwarf) did not react with probes for ACMV DNA-1 or DNA-2. Because each of the leafhopper-transmitted geminiviruses has a different vector species whereas the whitefly-transmitted geminiviruses all have the same vector, Bemisia tabaci, the genome homologies and antigenic relationships detected among members of the group could be explained if their coat proteins have a key role in transmission by vectors.

Comparison of Five Weeds as Hosts for Beet Leafhopper and Beet Curly Top Virus

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Serological Studies on Tomato Golden Mosaic Virus, a Geminivirus

SUMMARY Particles of tomato golden mosaic virus (TGMV), purified by an improved procedure, were used to prepare an antiserum which in gel double-diffusion tests with homologous virus gave a single precipitin line and had a titre of 1/256. TGMV was shown to be serologically related to another geminivirus, cassava latent virus, and distantly related to a leafhopper-transmitted geminivirus, beet curly top virus. No relationship could be detected to four other leafhopper-transmitted geminiviruses.

Beet Curly Top Virus

EPPO BulletinVolume 12, Issue 1 p. 157-162 Beet Curly Top Virus First published: January 1982 https://doi.org/10.1111/j.1365-2338.1982.tb01970.xAboutPDF 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 Volume12, Issue1January 1982Pages 157-162 RelatedInformation

Beet curly top virus from phloem exudate of Amsinckia douglasiana

SUMMARY Amsinckia douglasiana when infected with beet curly top virus (BCTV) produces more exudate, which is highly infective, than any other known host. Attempts were made to purify BCTV from the phloem exudate of infected Amsinckia douglasiana by differential centrifugation and sucrose density gradient fractionation. A260/280 ratio of virus preparations was 1.58; S values were 74 and 147. Infectivity was distributed among several fractions during density gradient purification. Electron microscopy revealed the presence of pentagonal and hexagonal particles of 14–23 nm, some of which were paired. The virus was insensitive to DNAse, RNAse, and trypsin when these enzymes were tested individually but infectivity was substantially decreased when the virus was subjected to trypsin treatment followed by DNAse, suggesting that DNA is associated with the beet curly top virus.

A study of the source of virus in the Pholem exudate appearing on leaves of Amscinckia infected with the beet curly top virus

Abstract Leaves of Amsinckia douglasiana discharging phloem exudate after infection with the beet curly top virus (BCTV) were studied with the electron microscope. Infected tissue differed from the noninfected in having much hyperplastic phloem characterized by abnormally high proportion of sieve elements, scarcity of companion cells, degenerating parenchyma cells, and some unusually large intercellular spaces. Many spaces contained amorphous debris. Particles resembling BCTV were discernible within the debris. Such particles were encountered also in the debris trapped between stomatal guard cells. Since the phloem exudate excreted from leaves of BCTV‐infected plants contains virus particles, and since the virus is found extremely rarely in sieve elements, we suggest (1) that most of BCTV particles apparently released into intercellular spaces are derived from degenerating parenchyma cells in which the virus had multiplied; (2) that the exudate is derived from sieve elements of the hyper‐plastic phloem in which the normal functional control by companion cells is lacking; (3) that the exudate leaks from the nontransporting sieve elements through cell walls into intercellular spaces and carries the virus to the outside. Initially, stomata may serve as exits for the infectious exudate, but subsequently ruptures in the epidermis are involved.

Beet curly top virus transmission by artificially fed and injected beet leafhoppers (Circulfer tenellus)

SUMMARYThe transmission of beet curly top virus (BCTV) by leafhoppers, Circulifer tenellus, fed virus through Parafilm® membranes was compared with their transmission when injected with virus from phloem exudates of Amsinckia douglasiana. Virus uptake from 32P‐labelled test solutions and the resulting virus transmission, as measured by an infectivity index, varied widely. By contrast, insects injected with virus transmitted with similar efficiencies. If insects were fasted for 3, 5, or 7 h before a 6 h acquisition access period on test solutions, their 32P, and presumably virus uptake, was greater than that of nonfasted insects and their variability in virus transmission decreased. The proportion of insects transmitting curly top virus, after fasting and given a 6 h acquisition access period, was similar to that of insects injected with virus. Maximum liquid uptake by the beet leafhopper occurred with a 12% sucrose solution.

A study of the source of virus in the Pholem exudate appearing on leaves of Amscinckia infected with the beet curly top virus

A study of the source of virus in the Pholem exudate appearing on leaves of Amscinckia infected with the beet curly top virus

Intracellular Location of Beet Curly Top Virus Antigen as Revealed by Fluorescent Antibody Staining

Intracellular Location of Beet Curly Top Virus Antigen as Revealed by Fluorescent Antibody Staining

Hyperplastic Phloem in Sugarbeet Leaves Infected with the Beet Curly Top Virus

Electron microscopy of sugarbeet leaves infected with the beet curly top virus confirmed earlier findings by light microscopy that the hyperplastic phloem consists mainly of sieve elements that are more or less abnormal in structure. Some parenchyma cells and occasional companion cells may be present. The hyperplastic phloem develops in the place of normal phloem and sometimes in the adjacent ground tissue and the xylem. The sieve elements vary in shape and may be haphazardly arranged. The protoplasts of the sieve elements have the usual characteristics of this type of cell. The sieve element plastids develop from chloroplasts if the hyperplasia occurs in chloroplast-containing parenchyma cells. The cell walls have sieve areas that often are less well differentiated than those of normal sieve elements. The hyperplastic growth in the phloem of curly top diseased plants is discussed with reference to plant tumors induced by certain other plant viruses.

HYPERPLASTIC PHLOEM IN SUGARBEET LEAVES INFECTED WITH THE BEET CURLY TOP VIRUS

Electron microscopy of sugarbeet leaves infected with the beet curly top virus confirmed earlier findings by light microscopy that the hyperplastic phloem consists mainly of sieve elements that are more or less abnormal in structure. Some parenchyma cells and occasional companion cells may be present. The hyperplastic phloem develops in the place of normal phloem and sometimes in the adjacent ground tissue and the xylem. The sieve elements vary in shape and may be haphazardly arranged. The protoplasts of the sieve elements have the usual characteristics of this type of cell. The sieve element plastids develop from chloroplasts if the hyperplasia occurs in chloroplast‐containing parenchyma cells. The cell walls have sieve areas that often are less well differentiated than those of normal sieve elements. The hyperplastic growth in the phloem of curly top diseased plants is discussed with reference to plant tumors induced by certain other plant viruses.

Relationship of Age of Plants and Resistance to a Severe Isolate of the Beet Curly Top Virus

DUFFUS, J. E., and I. 0. SKOYEN. 1977. Relationship of age of plants and resistance to a severe isolate of the beet curly top virus. Phytopathology 67: 151-154. Strains of the curly top virus capable of causing after more than 40% of the growing period had elapsed. Both appreciable damage to resistant cultivars of sugar beet are root yield and sucrose content were significantly reduced. found throughout the western United States. However, little Disease resistance appears to be associated with differences knowledge of the extent of the damage induced by these in incubation period rather than differences in the abilities of isolates was known. Field trials on sugar beets have indicated resistant cultivars to recover from the effects of virus that current strains of the curly top virus caused serious infection. losses, even when inoculated as late as 10 wk after seeding or Beet curly top virtually destroyed the sugar beet

Infectivity Neutralization Used in Serological Tests With Partially Purified Beet Curly Top Virus

Infectivity Neutralization Used in Serological Tests With Partially Purified Beet Curly Top Virus

Transmission of plant viruses by dodder

MECHANICS OF VIRUS TRANSMISSION BY DODDER In 1940 Bennett discovered that a virus could be transmitted from an infected to a healthy plant through a bridging dodder that was parasitizing both plants. Since then numerous workers have shown that many viruses are transmissible. The subject has been reviewed by Mooi-Bok (1949), Sibilia (1951), Bawden (1956, 1964), and Fulton (1964). Transmission probably involves an association of dodder and host cells, and directional movement of nutrients. It has long been known that dodder haustoria establish cellular connections with the host plant. Thoday (1911) found that the protoplasts of dodder and host phloem cells are in close association but do not appear to fuse. Bennett (1944b) hypothesized that dodder acquires viruses with the food materials from the phloem of the host. His studies of dodder stems inoculated with beet curly-top virus or with cucumber mosaic virus indicated that after entering the dodder a virus moves more rapidly toward growing points than in the opposite direction. He suggested that yellows-type viruses move from the phloem of the dodder into the phloem of the healthy host by temporary reversals of phloem nutrient flow and that mosaic-type viruses move from the parenchyma of the haustorium to that of the host through plasmodesmatal strands or from possible naked protoplasmic connections of dodder and host, as well as through the phloem. Bennett (1956) proposed that the above idea of temporary-reversalof-flow fits well with the theory that materials in the phloem move ". . . by mass flow of liquid content of the phloem from the regions of carbohydrate supply toward regions of food utilization." Cochran (1946) found that consistent transmission of tobacco mosaic virus could be achieved only by pruning the dodder and shading the healthy host while keeping the infected host in bright light; Bennett (1956) suggested that this forced a temporary reversal of phloem nutrient flow. Canova (1955) observed that Cuscuta epithymum Murr. acquired beet-yellows virus but did not transmit it, and Bennett (1960) found the same to be true for C. californica Hooker &

The stability of sugar beet curly-top virus strains

The stability of sugar beet curly-top virus strains