The DNA-B of the non-phloem-limited bean dwarf mosaic virus (BDMV) is able to move the phloem-limited Abutilon mosaic virus (AbMV) out of the phloem, but DNA-B of AbMV is unable to confine BDMV to the phloem

被引:20
|
作者
Levy, A [1 ]
Czosnek, H [1 ]
机构
[1] Hebrew Univ Jerusalem, Fac Agr, Robert H Smith Inst Plant Sci & Genet, IL-76100 Rehovot, Israel
关键词
Abutilon mosaic virus; bean dwarf mosaic virus; begomovirus; green fluorescence protein;
D O I
10.1023/B:PLAN.0000023662.25756.43
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Abutilon mosaic virus (AbMV) and bean dwarf mosaic virus (BDMV) are two phylogenetically related bipartite begomoviruses. While AbMV is restricted to phloem, BDMV spreads to non-phloem tissues. Cell-to-cell and long-distance movement of AbMV and BDMV were investigated after replacing the coat protein (CP) gene with the reporter gene encoding the green fluorescence protein (GFP). The DNA-A and DNA-B genomic components of AbMV and BDMV, and their pseudorecombinants (PR), were delivered to bean (Phaseolus vulgaris) seedlings and detached leaves with DNA-coated microprojectiles. Virus-associated fluorescence was observed with the confocal microscope. Delivery of AbMV and BDMV GFP reporters showed that the epidermal tissue was the main recipient of the viral DNA; the DNA-A of the two viruses was unable to move out of the recipient cells. AbMV DNA-A co-inoculated with AbMV DNA-B did not move from cell to cell in the epidermis and did not reach the phloem. However, co-inoculation of AbMV DNA-A with BDMV DNA-B resulted in PR cell-to-cell movement out of the epidermis and long-distance movement in the phloem. In contrast, BDMV DNA-A moved from cell to cell and over a long distance when co-inoculated with either its own DNA-B or with the DNA-B of AbMV. Thus, the DNA-B of the non-phloem-limited BDMV overcame the phloem limitation of AbMV. In the reciprocal case, the DNA-B of the phloem-limited AbMV did not confine the non-phloem limited BDMV to the phloem. Hence, we assume that the DNA-A component of BDMV includes determinants involved in the movement pattern of the virus in addition to the DNA-B-encoded BC1 and BV1 which have previously been shown to be involved in virus movement. The results also confirm that the CP is not necessary for virus movement; however, replacing the CP of AbMV and BDMV with GFP resulted in a decrease in symptom severity. DNA-B was involved in symptom severity; the B component of BDMV produced symptoms more severe than those induced by that of AbMV, whether in wild-type PRs or in PRs with CP-GFP replacement. It is interesting to note that when the GFP gene under the control of the CaMV 35S promoter (35S-GFP) was delivered to the bean tissue, with or without the DNA-B component of BDMV, GFP was expressed but did not move from cell to cell. However, when the 35S-GFP was delivered together with BDMV DNA-A and DNA-B, GFP showed cell-to-cell movement in the epidermis but was restricted to these cells. Hence, infection of cells with a functional bipartite begomovirus may facilitate cell-to-cell movement of macromolecules.
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页码:789 / 803
页数:15
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