Plant Virus Movement Research Articles

Long Distance Movement of Cauliflower Mosaic Virus in Infected Turnip Plants

Long Distance Movement of Cauliflower Mosaic Virus in Infected Turnip Plants

Diverse Groups of Plant RNA and DNA Viruses Share Related Movement Proteins that may Possess Chaperone-like Activity

Amino acid sequences of plant virus proteins mediating cell-to-cell movement were compared to each other and to protein sequences in databases. Two families of movement proteins have been identified, the members of which show statistically significant sequence similarity. The first, larger family (I) encompasses the movement proteins of tobamo-, tobra-, caulimo- and comoviruses, apple chlorotic leaf spot virus (ACLSV) and geminiviruses with bipartite genomes. Thus this family includes viruses which move by two methods, those requiring the coat protein for the cell-to-cell spread (comoviruses) and those not having this requirement (tobamoviruses). The previously unsuspected relationship between the movement proteins of RNA and DNA viruses having no RNA stage in their life cycle (geminiviruses) suggested that their movement mechanisms might be similar. The second, smaller family (II) consists of the movement proteins of tricornaviruses (bromoviruses, cucumoviruses, alfalfa mosaic virus and tobacco streak virus) and dianthoviruses. Alignment of the sequences of family I movement proteins highlighted two motifs, centred at conserved Gly and Asp residues, respectively, which are assumed to be crucial for the movement protein function(s). Screening the amino acid sequence database revealed another conserved motif that is shared by a large subset of family I movement proteins (those of caulimo- and comoviruses, and ACLSV) and the family of cellular 90K heat shock proteins (HSP90). Based on the analogy to HSP90, it is speculated that many plant virus movement proteins may mediate virus transport in a chaperone-like manner.

How do plant virus nucleic acids move through intercellular connections?

In addition to their function in transport of water, ions, small metabolites, and growth factors in normal plant tissue, the plasmodesmata presumably serve as routes for cell-to-cell movement of plant viruses in infected tissue. Virus cell-to-cell spread through plasmodesmata is an active process mediated by specialized virus encoded movement proteins; however, the mechanism by which these proteins operate is not clear. We incorporate recent information on the biochemical properties of plant virus movement proteins and their interaction with plasmodesmata in a model for transport of nucleic acids through plasmodesmatal channels. We propose that only single stranded (ss) nucleic acids can be transported efficiently through plasmodesmata, and that movement proteins function as molecular chaperones for ss nucleic acids to form unfolded movement protein-ss nucleic acid complexes. These complexes are targeted to plasmodesmata. Plasmodesmatal permeability is then increased following interaction with movement protein and the entire movement complex or its nucleic acid component is translocated across the plasmodesmatal channel.

Virus movement in infected plants

Abstract The movement of plant viruses from cell to cell is controlled by the action of virus‐encoded proteins. With the realization that understanding the mechanism involved will lead to a broad comprehension of virus disease and may open new ways to engineer virus resistance, this phenomenon has recently received much attention. Sequence homologies between different movement proteins indicates that they may share a common origin and some functional similarities. However, groupings based upon protein structure, function as determined by complementation in double infections or host range, are not correlated. The proteins influence plasmodesmatal structure to allow the passage of viral genomes or virus particles, and one protein has been shown to have single‐stranded nucleic acid binding properties. Transgenic plants, heterologous protein‐expression systems, and cell biological approaches will determine how these proteins interact with host components to elicit complex structural changes which result in sy...

The Movement of Viruses in Plants

The full expression of thc effects of a plant virus in a susceptible host is dependent upon the virus spreading to most, if not all, parts of that host. It is generally accepted that most plant viruses enter the initially infected cells of a plant through mechanical damage inflicted by a biological vector (e.g. arthro­ pod, nematode, fungus etc) or by mechanical abrasion (e. g. breaking of leaf hair). From the initially infected cell there are two forms of spread within the plant, namely short-distance and long-distance. Short-distance spread is from one cell to an adjacent cell. whereas long-distance spread is in the vascular system. For many viruses, particularly those causing mosaics, both forms of spread occur; cell-to-cell from the initially infected epidermal or mesophyll cell to the vascular bundle and long-distance to other parts of the plant followed by further short-distance spread. Other viruses may be limited to the vascular tissue, usually phloem, where they are introduced by their vector(s). There are, of course, intermediate situations; some viruses, such as BYVI spread in a limited manner from the phloem.

Studies on the Infection and the Movement of Plant Viruses

Studies on the Infection and the Movement of Plant Viruses

Presence of plasmodesmata in callus cultures of tobacco and carrot

Cultures of crown-gall callus and normal callus isolated from Nicotiana tabacum cv. Samsun and carrot callus were examined by light and electron microscopy for plasmodesmata. Both methods indicated their presence in crown-gall callus of tobacco. While plasmodesmata were not found in normal callus of tobacco and carrot using light microscopy, they were demonstrated with the electron micro-scope. The implication of these observations as related to movement of plant viruses within cultured tissue is discussed.

Distribution and Movement of Psorosis and Tristeza Viruses in Citrus Plants

Distribution and Movement of Psorosis and Tristeza Viruses in Citrus Plants

INFLUENCE OF HOST NUTRITION ON SYSTEMIC DEVELOPMENT OF TOBACCO MOSAIC

In two previous papers it was shown (3, 4) that the mineral nutrition of tobacco plants had a marked effect on their susceptibility to primary infection with a yellow strain of tobacco-mosaic virus. In the present paper the influence of host nutrition on systemic infection of this same virus in infected tobacco plants will be discussed. Several workers have studied the movement of virus in plants, but little attention has been given to the influence which host nutrition may have on systemic spread of virus. Boning (1), in 1928, published the results of an experiment dealing with the effect of nitrogen nutrition on mosaic-virus spread in tobacco. The tip of the largest leaf on each plant was inoculated. With actively growing plants an average of 3 days was required for the virus to pass 13 cm. from the tip of the leaf to the stem. With slow-growing, nitrogen-deficient plants an average of at least 6 days was necessary for the virus to pass from a leaf 12 cm. long. Boning concluded that the rapidity of virus-spread from an inoculated leaf was greatly decreased by nitrogen deficiency. Yolk (5) studied the effect of potassium, phosphorus, and nitrogen on the spread of streak in tomato plants grown in nutrient sand cultures, and inoculated just prior to fruiting. He concluded that the spread of streak disease was most rapid and the effect of the disease most severe in plants fertilized with an ample supply of potassium and phosphorus or in plants deficient in nitrogen.