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Detection of Mycoplasmalike Organism Antigens from Aster Yellows-Diseased Plants by Two Serological Procedures. R. C. Sinha, Chemistry and Biology Research Institute, Agriculture Canada, Ottawa, Ontario K1A 0C6; Nicole Benhamou, Chemistry and Biology Research Institute, Agriculture Canada, Ottawa, Ontario K1A 0C6. Phytopathology 73:1199-1202. Accepted for publication 29 March 1983. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1983. DOI: 10.1094/Phyto-73-1199.

Mycoplasmalike organism (MLO) antigens were detected by enzyme-linked immunosorbent assay (ELISA) and immunosorbent electron microscopy (IEM) in preparations partially purified from 5-g samples of aster (Callistephus chinensis) plants experimentally infected with aster yellows agent. The preparations containing MLOs at estimated concentrations as low as 4 μg/ml gave a positive reaction by ELISA (minimum absorbance value at 405 nm was >0.1), but the minimum concentration needed to trap the MLOs on the antiserum-coated grids in IEM tests was about 1.25 μg/ml. The MLOs were also detected by IEM in preparations from six experimentally infected host plant species, and the concentrations of MLOs in various species was estimated to vary from 80 to 20 μg/g of leaf tissue. The MLOs from aster yellows and clover phyllody-diseased plants appear to be antigenically indistinguishable. Partially purified preparations from 5 g samples of leaves infected with either peach-X or clover yellow edge agent did not give a positive reaction in ELISA or IEM tests with the antiserum against the MLOs from aster yellows-diseased plants. Also, the MLOs in preparations from aster yellows-diseased leaves were not trapped on grids coated with the antiserum against Spiroplasma citri in IEM tests.