Salicylic acid induces the accumulation of defense-related enzymes in Whangkeumbae pear and protects from pear black spot

The ability of salicylic acid (SA) to induce disease resistance was studied with Whangkeumbae pears affected by Alternaria kikuchiana Tanaka. SA (0.02, 0.2 and 2 mmol·L⁻¹ active ingredient) protected Whangkeumbae pear leaves from artificial infection when applied before inoculation. When the concentration of SA reached 0.2 mmol·L⁻¹, the disease-infected index was the lowest, and the rate of induced resistance reached 59.0%. The protection of Whangkeumbae pear leaves was associated with the activation of three defense-related enzymes, SOD, POD and PAL. Accumulation of three enzymes was induced locally in treated leaves and systemically. These results suggested that SA could induce systemic resistance in Whangkeumbae pear leaves by increasing defense-related compounds.