Periodic occurrence of an anti-TMV factor in the body of whiteflies carrying tomato yellow leaf curl virus

Abstract

Studies were carried out on an anti-TMV factor which occurs in homogenates prepared from whiteflies carrying tomato yellow leaf curl virus (TYLCV), but not in those prepared from “healthy” insects. This factor occurred periodically in whitefly bodies, i.e., it was found in homogenates of insects after 1, 2, and 13 days of acquisition feeding, but not in the bodies of those which were fed for 4 and 7 days on infected plants. The factor could be precipitated by increasing the ammonium sulfate concentration in the homogenate from 40 to 70% of saturation, but not at lower concentrations. When the anti-TMV active fraction was tested in vivo in whiteflies, no PARF (periodic acquisition related factor, an anti-TYLCV factor which had already been found) inhibiting effect was found. It was therefore suggested that the anti-TMV factor and PARF are different, and that both are apparently connected to the phenomenon of periodic acquisition.