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Cytology and Histology

Lysosomal Distribution and Acid Phosphatase Activity in White Clover Infected with Clover Yellow Mosaic Virus. J. C. Tu, Biological Sciences Electron Microscope Laboratory, University of Alberta, Edmonton, Alberta, Canada, T6G 2E1; Phytopathology 66:588-593. Accepted for publication 14 October 1975. DOI: 10.1094/Phyto-66-588.

More lysosomes were observed in thin sections of leaves and root nodules of white clover (Trifolium repens) infected with clover yellow mosaic virus (CYMV) than in sections from virus-free tissues. In the leaf, lysosomes were found in vacuoles or in the cytoplasm near the vacuole. In the root nodule, they were generally seen near the plasma membrane and in the vicinity of virus aggregates. Biochemical assays and histochemical localization tests showed more acid phosphatase (a lysosomal enzyme) activity in the sap of leaves and root nodules of CYMV-infected than in the healthy plants. The specific activity of acid phosphatase in leaves and root nodules of the CYMV-infected plants increased approximately 100% over the healthy controls. The increased lysosomes and acid phosphatase activity in relation to early senescence of the leaves and early degeneration of the root nodules in the virus pathogenesis are discussed.