THE PLANT CELL, Vol 9, Issue 11 2051-2063, Copyright © 1997 by American Society of Plant Biologists
Satellite RNA-Mediated Resistance to Turnip Crinkle Virus in Arabidopsis Involves a Reduction in Virus Movement
Q. Kong, J. Wang and A. E. Simon
Department of Biochemistry and Molecular Biology and Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, Massachusetts 01003-4505
Satellite RNAs (sat-RNAs) are parasites of viruses that can mediate
resistance to the helper virus. We previously showed that a sat-RNA
(sat-RNA C) of turnip crinkle virus (TCV), which normally intensifies
symptoms of TCV, is able to attenuate symptoms when TCV contains the coat
protein (CP) of cardamine chlorotic fleck virus (TCV-CPCCFV). We have now
determined that sat-RNA C also attenuates symptoms of TCV containing an
alteration in the initiating AUG of the CP open reading frame (TCV-CPm).
TCV-CPm, which is able to move systemically in both the TCV-susceptible
ecotype Columbia (Col-0) and the TCV-resistant ecotype Dijon (Di-0),
produced a reduced level of CP and no detectable virions in infected
plants. Sat-RNA C reduced the accumulation of TCV-CPm by <25% in
protoplasts while reducing the level of TCV-CPm by 90 to 100% in
uninoculated leaves of Col-0 and Di-0. Our results suggest that in the
presence of a reduced level of a possibly altered CP, sat-RNA C reduces
virus long-distance movement in a manner that is independent of the
salicylic acid-dependent defense pathway.