Enhancing disease resistance in harvested mango (Mangifera indica L. cv. 'Matisu') fruit by salicylic acid

To learn how salicylic acid (SA) may affect disease resistance in mango, mango fruit (Mangifera indica L. cv. 'Matisu') were treated with 1 mmol L-1 SA solution under vacuum infiltration for 2 min at a low pressure (-80 kPa) and for an additional 10 min at air pressure. The fruit were inoculated with anthracnose (Colletotichum gloeosporioides Penz.) spore suspension (1 x 10(4) CFU mL(-1)) and incubated at 13 degrees C, 85-95% RH. Disease incidence and lesion diameter in/on the SA-treated fruit were 37.5% and 20.9% lower than that in/on control fruit on the 4th day of incubation. The study further showed that activities of defensive enzymes in the fruit were significantly enhanced by SA treatment. The activity of phenylalanine ammonia-lyase (PAL) and beta-1,3-glucanase in the SA-treated fruit was over 6- or 0.9-fold higher than that in control fruit on the 4th day after the fruit being treated with SA, respectively. Level of hydrogen peroxide (H2O2) or superoxide radicals (O-2(-)) generation rate in SA-treated fruit was 22.3% or 79.4% higher than that in controls on the 8th day after the fruit being treated with SA, respectively. These results suggested that PAL and beta-1,3-glucanase, as well as H2O2 or O-2(-), may be involved in the enhancement of disease resistance in mango fruit. (c) 2006 Society of Chemical Industry.