Influence of actinomycin D, ethephon, cycloheximide and chloramphenicol on the infection of a resistant and a susceptible cucumber cultivar with cucumber mosaic virus (price's no. 6 strain)

Abstract

While China-K cucumber plants are resistant to CMV, their response to TMV and TRSV is closer to that of Ashley, which is susceptible to CMV. Resistance of China-K to strain P6 of CMV could be partially overcome by actinomycin D, which restricts transcription, but not by ethephon (2-chloroethyl-phosphonic acid), which, while inducing senescence, did not restrict transcription. Inhibition of chloroplast ribosome function with chloramphenicol and cytoplasmic ribosomes with cycloheximide indicated that cytoplasmic ribosomes were essential for virus replication. Neither treatment promoted enhanced virus accumulation. The results are consistent with the view that an induced compound, whose synthesis depends on transcription of host DNA but not translation on chloroplast ribosomes, assists in limiting virus multiplication. It was not possible to conclude whether or not expression of resistance required active cytoplasmic ribosomes. Attempts to demonstrate the presence of such a compound by more direct approaches are referred to.