Presence of a clostero-like virus and a bacilliform virus in pineapple plants in Australia

Abstract

When sap of asymptomatic or mealybug wilt-affected pineapple plants of the Smooth Cayenne group was negatively stained and examined in an electron microscope, clostero-like virus particles were occasionally seen. However, numerous clostero-like virus particles and occasionally some bacilliform particles were seen in partially purified preparations from both asymptomatic and wilted pineapple leaves. An antiserum, made by injecting partially purified preparations of clostero-like particles into a rabbit, trapped and decorated the clostero-like particles. Using this antiserum, the clostero-like particles (c. 1700 -1900x12 nm) were found in almost all plants tested of Smooth Cayenne selections C10, C13, C30 and F-180, the hybrid cv. 53-116 and a selection of the rough leaf Queen group. The particles were more readily trapped from extracts of roots of hybrid cv. 53-116 and Smooth Cayenne selection C10 than from leaves, crowns and fruits. They were not detected in seedlings of a cross between a Queen selection and the Smooth Cayenne selection C10. The clostero-like particles are similar to those reported to occur in pineapple plants in Hawaii and South Africa. This is the first report of their occurrence in Australia. Trapping and decoration tests of particles in pineapples in quarantine from Brazil, France, Malaysia and Taiwan indicated that a similar clostero-like virus occurs in all these countries. The bacilliform particles measured about 133x33 nm. They were trapped and decorated by the Queensland pineapple virus antiserum and also by an antiserum to sugarcane bacilliform badnavirus. They were detected occasionally in various smooth leaf and rough leaf pineapples in north and south Queensland and northern New South Wales. However, in one commercial planting of Smooth Cayenne selection C10 in south Queensland, bacilliform particles were trapped from 29/47 plants. This is the first report of a small bacilliform virus, probably belonging to the badnavirus group, occurring in pineapple plants. The relationship of the clostero-like and bacilliform viruses to yield loss and mealybug wilt in pineapples is unknown.