Influence of different factors on the reduced susceptibility of potato virus X infected potato leaves to Alternaria solani

Abstract

SUMMARYFactors influencing potato virus X (PVX)-induced resistance to Alternaria solani in potato leaves are reported. The inhibition of fungal infection was dependent on the time interval between viral and fungal inoculations, fungal inoculum load, age of the host, virus strain and host cultivar. The maximum reduction in fungal infection was observed when a gap of 120 h occurred between PVX and A. solani inoculations. The clearest interactive effect in terms of reduced susceptibility to A. solani infection was seen at a fungal spore concentration of 1000 spores/ml in 20-day-old plants. This effect was gradually reduced following an increase in inoculum load and age of the host.The extent of pathogen interaction was also affected by different virus strains and host cultivars. Maximum inhibition of fungal disease occurred with the PVX-ring spot strain. Of five potato cultivar tested, the maximum inhibition occurred in Kufri Chandramukhi and Kufri Sindhuri, the cultivars most susceptible to A. solani.