Determination of the role of salicylic acid and Benzothiadiazole on physico-chemical alterations caused by Cucumber mosaic virus in tomato Rana M. Sabir Tariq & Khalid P. Akhtar & Amjad Hameed & Najeeb Ullah & Muhammad Y. Saleem & Imran ul Haq Accepted: 30 August 2017 # Koninklijke Nederlandse Planteziektenkundige Vereniging 2017 Abstract Shoe-string disease caused by Cucumber mo- saic virus (CMV) is one of the major threats to tomato production worldwide. The alteration in some biochem- ical parameters in leaves of the susceptible tomato ge- notype (Nagina) associated with CMV infection and the effect of exogenous application of salicylic acid (SA) and benzothiadiazole (BTH) were studied in this paper. Results showed that exogenous treatment with SA and BTH not only led to plants which gave significantly more yield than diseased controls (DC), but also delayed symptom expression and reduced disease severity. Analysis of biochemical parameters indicated that ex- ogenous application of elicitors and viral infection, sig- nificantly affected the activity of peroxidase (POD), superoxide dismutase (SOD), catalase (CAT) and ascor- bate peroxidase (APX). Compared to the DC plants, minimum disease severity and maximum number of fruit were recorded after a single dose of SA + BTH. Maximum plant height was recorded after weekly ap- plication of SA and maximum fruit yield per plant was gained with single dose of SA. Moreover, the activity of POD was significantly elicited many-fold after weekly application of SA + BTH, while higher amount of SOD was recorded with single dose of SA. The activity of CAT was also significantly accelerated after weekly application of SA + BTH while increased level of APX was noticed with single dose of BTH. In conclu- sion, the combined application of SA and BTH played an important role in induction of defense mechanism against CMV infection and can be useful in tomato disease management programs. Keywords CMV . Salicylic acid . BTH . Tomato Introduction Tomato (Solanum lycopersicum L.) belongs to the fam- ily Solanaceae and is the second most important vege- table crop grown throughout the world (Akhtar et al. 2016) as it is a rich source of carotenoids, ascorbic acid, vitamin A, vitamin E, folate, flavonoids and potassium (Leonardi et al. 2000). Phenolic compounds, ascorbic acid and carotenoids of tomato have antioxidant prop- erties and their consumption can reduce the risk of prostate cancer (Giovannucci 1999). Tomato production is threatened by Cucumber mosaic virus (CMV) in tomato growing countries with a temperate climate (Kyriakopoulou et al. 2000). CMV is principally trans- mitted by the aphid Myzus persicae and has the largest host range (1300 species in more than 500 genera of over 100 families) (Garcia-Arenal and Palukaitis 2008). It is an important plant pathogen as well as a major model for basic research (Palukaitis and García-Arenal 2003). On the basis of serological relationships and nucleic acid identities, CMV has been classified into Eur J Plant Pathol DOI 10.1007/s10658-017-1332-4 R. M. Sabir Tariq : I. ul Haq (*) Department of Plant Pathology, University of Agriculture, Faisalabad, Pakistan e-mail: imran_1614@yahoo.com K. P. Akhtar : A. Hameed : N. Ullah : M. Y. Saleem Nuclear Institute for Agriculture and Biology (NIAB), P. O. Box, 128, Jhang road, Faisalabad, Pakistan