Mapping determinants within cucumber mosaic virus and its satellite RNA for the induction of necrosis in tomato plants.
A mutant of the WL47 satellite (WL47-sat) RNA of cucumber mosaic virus (CMV), constructed in vitro, induces lethal necrosis in tomato plants when associated with either of two subgroup II strains of CMV: LS- or WL-CMV (D. E. Sleat and P. Palukaitis, Proc. Natl. Acad. Sci. USA 87:2946-2950, 1990). The phenotype of this mutant (WLM2-sat RNA) has been examined on tomato plants, after co-inoculation with a wider range of CMV strains. Necrosis was observed when WLM2-sat RNA was associated with any of the subgroup II CMV strains tested. However, WLM2-sat RNA ameliorated the symptoms induced by subgroup I CMV strains without inducing necrosis. Inoculation with WLM2-sat RNA with pseudorecombinants formed between subgroup I and subgroup II CMV strains showed an association of the necrosis induction phenotype with RNA 2 of the subgroup II strains. In contrast to WLM2-sat RNA, infectious transcripts of the naturally necrogenic D4-sat RNA induced lethal necrosis in tomato with all CMV strains tested. Experiments involving the exchange of sequences between WLM2- and D4-sat RNAs indicated that nucleotides sequences in either of two separate regions could influence the necrosis phenotype. Thus, the subgroup-specific necrosis-inducing phenotype may be due to subtle alterations in secondary and/or tertiary structure in the satellite RNA, as well as the presence or absence of particular nucleotide sequences.
Sleat
D E
DE
Department of Plant Pathology, Cornell University, Ithaca, NY 14853.
Zhang
L
L
Palukaitis
P
P
D001483:Base Sequence; D016923:Cell Death; D017799:Cucumovirus / Q000235:genetics* / Q000276:immunology; D004279:DNA, Viral; D008969:Molecular Sequence Data; D010641:Phenotype; D012367:RNA, Viral / Q000032:analysis / Q000235:genetics; D011995:Recombination, Genetic; D014675:Vegetables / Q000166:cytology / Q000382:microbiology*
D004279:DNA, Viral; D012367:RNA, Viral