Switches in the mode of transmission select for or against a poorly aphid-transmissible strain of potato virus Y with reduced helper component and virus accumulation.
A poorly aphid-transmissible potato virus Y (PVY-PAT) variant emerged after several cycles of mechanical transmission of an initially aphid-transmissible (AT) isolate. Sequence analysis of the N-terminal region of the helper component-proteinase (HC-Pro) gene revealed a Lys to Glu change at a position previously found to abolish the HC-Pro aphid transmission activity in several potyviruses. Two cycles of aphid transmission allowed the virus population to evolve towards an AT form (PVY-ATnew) where a Glu to Lys change was observed. PVY-PAT produced lower amounts of coat protein and the accumulation of its HC-Pro in infected plants decreased from 7 to 28 days post-inoculation, as compared to PVY-ATnew. RT-PCR and restriction analysis showed that the two virus populations co-existed in the PVY-AT isolate and that the AT form was counter-selected during mechanical transmission. These observations suggest that the Lys to Glu substitution leads to decreased stability of HC-Pro resulting in poor transmissions by aphids, and further strengthen the idea that HC-Pro is involved in the accumulation of potyvirus in infected plants.
Legavre
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T
Laboratoire de biologie Cellulaire, INRA, 78026 Versailles, France.
Maia
I G
IG
Casse-Delbart
F
F
Bernardi
F
F
Robaglia
C
C
D000595:Amino Acid Sequence; D000818:Animals; D001042:Aphids / Q000821:virology; D001483:Base Sequence; D002213:Capsid / Q000378:metabolism*; D036022:Capsid Proteins; D003546:Cysteine Endopeptidases / Q000235:genetics / Q000378:metabolism*; D004279:DNA, Viral; D007303:Insect Vectors; D008969:Molecular Sequence Data; D010935:Plant Diseases / Q000821:virology; D017800:Potyvirus / Q000472:pathogenicity*; D012641:Selection, Genetic; D011198:Solanum tuberosum / Q000821:virology; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*
D036022:Capsid Proteins; D004279:DNA, Viral; D014764:Viral Proteins; C090960:coat protein, Potato virus Y; D003546:Cysteine Endopeptidases; C072775:HC-Pro protein, potyvirus