Screening of tomato (Solanum lycopersicon L.) genotypes by inducing systemic resistance against early blight disease caused by Alternaria solani

Abstract

Early blight of tomato (Solanum lycopersicon L.) incited by Alternaria solani is highly destructive disease in the world. Environmental factors significantly impact early blight epidemics, leading to the loss of up to 78 per cent of tomato production. Twenty tomato genotypes were used in this study to identify the early blight resistant and susceptible genotypes selected to represent a range of reactions when screened under field conditions. The tomato plants were evaluated for early blight disease by using Per cent Disease Index (PDI). Pusa Uphar (20.18%) and Sankaranti (20.18%) showed resistance to early blight disease among the twenty genotypes. Anaka Kerala (61.25%), Arka Vikas (61.76%), Pusa Rohini (53.65%), Ashoka (50.60%) and Paiyur1 (56.08%) genotypes were found highly susceptible based on early blight disease intensity. Spore inoculation of A. solani was sprayed into tomato plants, it was discovered that the number of defense-inducing compounds viz., total phenols, peroxidase (PO), polyphenol oxidase (PPO) and phenylalanine ammonia lyase (PAL) has increased. Among the genotypes, Pusa Uphar (T2) and Sankaranti (T1) genotypes showed a high level of defense enzyme production. After tomato plants were exposed to pathogens through artificial inoculation, the activity of these defensive enzymes and compounds was highly induced in the resistant and sensitive germplasm than in the control.