Effects of exogenous salicylic acid on the resistance of Kentucky bluegrass to brown patch and expression of PR1 and NPR1 resistance genes

To explore the effect of external salicylic acid (SA) on the resistance of Kentucky bluegrass (Poa pratensis) to brown patch, Kentucky bluegrass variety ‘Midnight’ was divided into three groups and treated with 0.05 mmol·L^–1 SA and Rhizoctonia solani. The percent of disease infection and disease index were measured, and the efficacy of resistance induced was calculated. The relative expression of disease resistance genes PR1 and NPR1 was assessed. The results showed that external SA could significantly (P < 0.05) decrease the plant infection percent and disease index of brown patch on Kentucky bluegrass, and the highest efficacy of resistance induced by SA was 53%. After spraying SA and inoculation, the relative expression of PR1 and NPR1 increased significantly (P < 0.05).