Disease Severity Index as It Affects Responses in Potato Virus X–Challenged Potato Varieties

Abstract

ABSTRACTPotato (Solanum tuberosum L.) is an important vegetable crop but can have significant yield loss due to disease, including those caused by viruses. The physiology of host plants can be affected by viruses, which can lead to symptom expression. Study of biochemical activities helps to understand the phenomena of plant disease resistance and can be useful in screening for natural resistance in host plants against viruses. Biochemical activities were analyzed among varieties from potato rated as being in susceptible (S), moderately susceptible (MS), and moderately resistant (MR) reaction groups on the basis of disease severity index. Reaction group status was confirmed through enzyme-linked immunosorbent assay (ELISA) of potato germplasm showing symptoms of potato virus X (PVX). Phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO), and sugar, soluble protein, and total amino acids contents were compared in virus-infected potato varieties from the reaction groups. There was not much variation in PAL activity among varieties in the same reaction group. The PPO and total sugar contents were lower in varieties of the MR reaction group compared to S varieties. Total soluble protein content was higher in S and MS varieties. Amino acid content was low in S and MS reaction groups. Comparison of biochemical analysis in varieties based on reaction groups against PVX could be helpful in selection of varieties for better yield.