Detection of Mycoplasmalike Organism Antigens from Aster Yellows-Diseased Plants by Two Serological Procedures

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Abstract
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 MLO at estimated concentrations as low as 4 .mu.g/ml gave a positive reaction by ELISA (minimum absorbance value at 405 nm was > 0.1), but the minimum concentration needed to trap the MLO on the antiserum-coated grids in IEM tests was about 1.25 .mu.g/ml. The MLO were also detected by IEM in preparations from 6 experimentally infected host plant species; the concentrations of MLO in various species was 80-20 .mu.g/g of leaf tissue. The MLO from aster yellows and clover phyllody-diseased plants apparently were 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 MLO from aster yellow-diseased plants. Also, the MLO in preparations from aster yellows-diseased leaves were not trapped on grids coated with the antiserum against Spiroplasma citri in IEM tests. [The plant species tested were celery (Apium graveolens), periwinkle (Catharanthus roseus), oat (Avena sativa), wheat (Triticum durum), ladino clover (Trifolium repens) and red clover (T. pratense)].