1978 Volume 44 Issue 5 Pages 570-577
As the indicator plant of hop stunt disease (HSD) agent, cucumber plants were used to investigate the properties of HSD agent. HSD agent in crude sap from diseased cucumber plants was not inactivated after heating at 84C for 10min, lost its infectivity when diluted 1/10, 000, and kept for one day at 20C, but not after three days at 4C. HSD agent was easily extractable with buffers of high ionic strength (0.5M K2HPO4). The agent remained in the supernatant of high speed centrifugation (113, 000×g, 2 hours), was extracted with phenol and precipitated with ethanol. The agent was inactivated with RNase, but not with DNase. Fraction showing high infectivity was detected between 6S and 9S by the 5-20% sucrose density gradient centrifugation. The results indicate that HSD agent is a low molecular weight ribonucleic acid, a viroid.