Two amino acids on 2a polymerase of Cucumber mosaic virus co-determine hypersensitive response on legumes

2003 ◽  
Vol 46 (1) ◽  
pp. 40
Author(s):  
Xiaorong TAO
2008 ◽  
Vol 21 (7) ◽  
pp. 937-946 ◽  
Author(s):  
M. R. Hajimorad ◽  
A. L. Eggenberger ◽  
J. H. Hill

In Rsv1-genotype soybean, Soybean mosaic virus (SMV)-N (an avirulent isolate of strain G2) elicits extreme resistance (ER) whereas strain SMV-G7 provokes a lethal systemic hypersensitive response (LSHR). SMV-G7d, an experimentally evolved variant of SMV-G7, induces systemic mosaic. Thus, for Rsv1-genotype soybean, SMV-N is avirulent whereas SMV-G7 and SMV-G7d are both virulent. Exploiting these differential interactions, we recently mapped the elicitor functions of SMV provoking Rsv1-mediated ER and LSHR to the N-terminal 271 amino acids of P3 from SMV-N and SMV-G7, respectively. The phenotype of both SMV-G7 and SMV-G7d were rendered avirulent on Rsv1-genotype soybean when the part of the genome encoding the N-terminus or the entire P3 cistron was replaced with that from SMV-N; however, reciprocal exchanges did not confer virulence to SMV-N-derived P3 chimeras. Here, we describe virulent SMV-N-derived P3 chimeras containing the full-length or the N-terminal P3 from SMV-G7 or SMV-G7d, with or without additional mutations in P3, that were selected on Rsv1-genotype soybean by sequential transfers on rsv1 and Rsv1-genotype soybean. Sequence analyses of the P3 and helper-component proteinase (HC-Pro) cistrons of progeny recovered from Rsv1-genotype soybean consistently revealed the presence of mutations in HC-Pro. Interestingly, the precise mutations in HC-Pro required for the adaptation varied among the chimeras. No mutation was detected in the HC-Pro of progeny passaged continuously in rsv1-genotype soybean, suggesting that selection is a consequence of pressure imposed by Rsv1. Mutations in HC-Pro alone failed to confer virulence to SMV-N; however, reconstruction of mutations in HC-Pro of the SMV-N-derived P3 chimeras resulted in virulence. Taken together, the data suggest that HC-Pro complementation of P3 is essential for SMV virulence on Rsv1-genotype soybean.


1999 ◽  
Vol 12 (7) ◽  
pp. 628-632 ◽  
Author(s):  
Sek-Man Wong ◽  
Sharon Swee-Chin Thio ◽  
Michael H. Shintaku ◽  
Peter Palukaitis

The M strain of cucumber mosaic virus (CMV) does not infect squash plants systemically and moves very slowly in inoculated cotyledons. Systemic infection and an increase in the rate of local movement were observed when amino acids 129 or 214 of the M-CMV capsid protein (CP) were altered to those present in the Fny strain of CMV. While the opposite alterations to the CP of Fny-CMV inhibited systemic infection of squash, they did not show the same effects on the rates of both cell-to-cell and long-distance movement. However, the ability of CMV to infect squash systemically was affected by the rate of cell-to-cell movement.


2007 ◽  
Vol 88 (12) ◽  
pp. 3445-3451 ◽  
Author(s):  
Min Sook Hwang ◽  
Kyung Nam Kim ◽  
Jeong Hyun Lee ◽  
Young In Park

The cucumber mosaic virus (CMV)-encoded 3a movement protein (MP) is indispensable for CMV movement in plants. We have previously shown that MP interacts directly with the CMV-encoded 2a polymerase protein in vitro. Here, we further dissected this interaction and determined the amino acid sequences that are responsible for the MP and 2a polymerase protein interaction. Both the N-terminal 21 amino acids and the central GDD motif of the 2a polymerase protein were important for interacting with the MP. Although each of the regions alone was sufficient for the interaction with MP, quantitative yeast two-hybrid analyses showed that they acted synergistically to enhance the binding affinity. The MP N-terminal 20 amino acids were sufficient for interacting with the 2a polymerase protein, and the serine residue at position 14 played a critical role in the interaction. Multiple sequence alignment showed that the 2a protein interacting regions and the serine at position 14 in the MP are highly conserved among subgroup I and II CMV isolates.


2008 ◽  
Vol 21 (7) ◽  
pp. 931-936 ◽  
Author(s):  
A. L. Eggenberger ◽  
M. R. Hajimorad ◽  
J. H. Hill

In soybean, Rsv1, a single dominant resistance gene, invokes extreme resistance (ER) against most Soybean mosaic virus (SMV) strains, including SMV-N, but not SMV-G7, which provokes a virulent lethal systemic hypersensitive response (LSHR). The elicitor functions of the two viruses provoking Rsv1-mediated ER and LSHR have been mapped to the N-terminal 271 amino acids of P3 from SMV-N and SMV-G7, respectively, which differ by nine residues between the two strains. To identify amino acids of P3 from SMV-N provoking Rsv1-mediated ER, the unique residues of SMV-G7 were substituted with those of SMV-N. Of the mutants tested on Rsv1-genotype soybean, only SMV-G7I788R and SMV-G7T948A lost virulence. However, substitution of amino acids of SMV-N, individually or in combination, with the reciprocal residues from SMV-G7 at these two positions failed to confer virulence to SMV-N. In the search for additional virulence determinants, a series of SMV-N chimeras was generated in which fragments within a region from near the middle of the helper-component proteinase (HC-Pro) cistron to the 5′ end of the cytoplasmic inclusion cistron, nucleotides 1,605 to 3,787, were replaced with those of SMV-G7. Only SMV-N-derived chimeras harboring the 3′ region of HC-Pro, at least from nucleotide 2,013, and the entire 5′ end of P3 (nucleotides 2,430 to 3,237) from SMV-G7 were virulent whereas reciprocal exchanges resulted in loss of SMV-G7 virulence. This region of HC-Pro differs by three amino acids between SMV-N and SMV-G7. Analyses of SMV-G7-derived HC-Pro site-directed mutants showed that only SMV-G7M683R lost virulence on Rsv1-genotype soybean; however, SMV-NR682M failed to gain virulence. Nevertheless, an SMV-N derived mutant with three concurrent substitutions, R682M+R787I+A947T, gained virulence. The data indicate that both P3 and HC-Pro are involved in virulence of SMV on Rsv1-genotype soybean.


2001 ◽  
Vol 75 (17) ◽  
pp. 8045-8053 ◽  
Author(s):  
Hideaki Nagano ◽  
Kazuyuki Mise ◽  
Iwao Furusawa ◽  
Tetsuro Okuno

ABSTRACT Plant viruses have movement protein (MP) gene(s) essential for cell-to-cell movement in hosts. Cucumber mosaic virus (CMV) requires its own coat protein (CP) in addition to the MP for intercellular movement. Our present results using variants of both CMV and a chimeric Brome mosaic virus with the CMV MP gene revealed that CMV MP truncated in its C-terminal 33 amino acids has the ability to mediate viral movement independently of CP. Coexpression of the intact and truncated CMV MPs extremely reduced movement of the chimeric viruses, suggesting that these heterogeneous CMV MPs function antagonistically. Sequential deletion analyses of the CMV MP revealed that the dispensability of CP occurred when the C-terminal deletion ranged between 31 and 36 amino acids and that shorter deletion impaired the ability of the MP to promote viral movement. This is the first report that a region of MP determines the requirement of CP in cell-to-cell movement of a plant virus.


2004 ◽  
Vol 85 (1) ◽  
pp. 221-230 ◽  
Author(s):  
Sang Hyon Kim ◽  
Natalia O. Kalinina ◽  
Igor Andreev ◽  
Eugene V. Ryabov ◽  
Alexander G. Fitzgerald ◽  
...  

Virology ◽  
2007 ◽  
Vol 358 (1) ◽  
pp. 109-118 ◽  
Author(s):  
Katalin Salánki ◽  
Ákos Gellért ◽  
Gábor Náray-Szabó ◽  
Ervin Balázs

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