Lettuce mosaic virus pathogenicity determinants in susceptible and tolerant lettuce cultivars map to different regions of the viral genome.
Full-length infectious cDNA clones were constructed for two isolates (LMV-0 and LMV-E) of Lettuce mosaic virus (LMV), a member of the genus Potyvirus. These two isolates differ in pathogenicity in susceptible and tolerant-resistant lettuce cultivars. In susceptible plants, LMV-0 induces mild mosaic symptoms, whereas LMV-E induces severe stunting, leaf deformation, and a necrotic mosaic. In plants carrying either of the two probably allelic recessive resistance genes mol1 or mol2, LMV-0 is restricted partially to the inoculated leaves. When a systemic invasion does occur, however, symptoms fail to develop. LMV-E overcomes the protection afforded by the resistance genes, resulting in systemic mosaic symptoms. Analysis of the behavior of recombinants constructed between the two virus isolates determined that the HC-Pro protein of LMV-E causes the severe stunting and necrotic mosaic induced by this isolate in susceptible cultivars. In contrast, the ability to overcome mol resistance and induce symptoms in the resistant-tolerant cultivars was mapped to the 3' half of the LMV-E genome. These results indicate that the ability to induce severe symptoms and to overcome the protection afforded by the recessive genes mol1 or mol2 are independent phenomena.
Redondo
E
E
Virologie, UMR GDPP, IBVM, INRA, Villenave d'Ornon, France.
Krause-Sakate
R
R
Yang
S J
SJ
Lot
H
H
Le Gall
O
O
Candresse
T
T
D003001:Cloning, Molecular; D003546:Cysteine Endopeptidases / Q000235:genetics; D004279:DNA, Viral; D016679:Genome, Viral; D018545:Lactuca / Q000145:classification / Q000378:metabolism / Q000821:virology*; D009336:Necrosis; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism / Q000821:virology; D017800:Potyvirus / Q000302:isolation & purification / Q000472:pathogenicity*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D014758:Viral Core Proteins; D014764:Viral Proteins / Q000235:genetics
D004279:DNA, Viral; D011993:Recombinant Fusion Proteins; D014758:Viral Core Proteins; D014764:Viral Proteins; D003546:Cysteine Endopeptidases; C072775:HC-Pro protein, potyvirus