Effect of abscissic acid on tobacco mosaic virus

Abscisic acid (ABA) did not affect the infectivity of tobacco mosaic virus (TMV) in vitro. The same dilutions of ABA when applied on the leaves of Chenopodium amaranticolor Coste and Reyn. at different intervals before inoculation affected development of local lesions variably at different dilutions. The inhibition of local lesion formation was reduced at other intervals leading to stimulation at thirty minutes and six hours intervals. Post-inoculation treatments with 2 mg/l of ABA gave stimulation of local lesion formation, though other dilutions gave inhibition. Viral concentration was stimulated in the tomato seedlings root dipped in 0.2 mg/l of ABA for 6 hours and inoculated 24 hours after transplantation. Incorporation of different concentrations of ABA into tissue culture medium reduced the growth of the TMV infected tobacco callus tissue and stimulated the infectivity of the tissue grown over it assayed after three weeks.