Cucumber mosaic virus 2a polymerase and 3a movement proteins independently affect both virus movement and the timing of symptom development in zucchini squash.
The basis for differences in the timing of systemic symptom elicitation in zucchini squash between a pepper strain of Cucumber mosaic virus (Pf-CMV) and a cucurbit strain (Fny-CMV) was analysed. The difference in timing of appearance of systemic symptoms was shown to map to both RNA 2 and RNA 3 of Pf-CMV, with pseudorecombinant viruses containing either RNA 2 or RNA 3 from Pf-CMV showing an intermediate rate of systemic symptom development compared with those containing both or neither Pf-CMV RNAs. Symptom phenotype was shown to map to two single-nucleotide changes, both in codons for Ile at aa 267 and 168 (in Fny-CMV RNAs 2 and 3, respectively) to Thr (in Pf-CMV RNAs 2 and 3). The differential rate of symptom development was shown to be due to differences in the rates of cell-to-cell movement in the inoculated cotyledons, as well as differences in the rate of egress of the virus from the inoculated leaves. These data indicate that both the CMV 3a movement protein and the CMV 2a polymerase protein affect the rate of movement of CMV in zucchini squash and that these two proteins function independently of each other in their interactions with the host, facilitating virus movement.
Choi
Seung Kook
SK
Plant Virus GenBank, Division of Environmental and Life Sciences, Seoul Women's University, Seoul 139-774, Korea.
Palukaitis
Peter
P
Scottish Crop Research Institute, Invergowrie DD2 5DA, UK.
Min
Byoung Eun
BE
Plant Virus GenBank, Division of Environmental and Life Sciences, Seoul Women's University, Seoul 139-774, Korea.
Lee
Mi Yeon
MY
Plant Virus GenBank, Division of Environmental and Life Sciences, Seoul Women's University, Seoul 139-774, Korea.
Choi
Jang Kyung
JK
Division of Biological Environment, Kangwon National University, Chuncheon 200-701, Korea.
Ryu
Ki Hyun
KH
Plant Virus GenBank, Division of Environmental and Life Sciences, Seoul Women's University, Seoul 139-774, Korea.
D017799:Cucumovirus / Q000201:enzymology / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D028464:Cucurbita / Q000821:virology*; D015967:Gene Expression Regulation, Viral; D010935:Plant Diseases / Q000821:virology; D018515:Plant Leaves / Q000821:virology; D053830:Plant Viral Movement Proteins; D012319:RNA Polymerase II / Q000235:genetics / Q000378:metabolism*; D012367:RNA, Viral / Q000235:genetics / Q000378:metabolism*; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*
D053830:Plant Viral Movement Proteins; D012367:RNA, Viral; D014764:Viral Proteins; D012319:RNA Polymerase II