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

Abstract

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 × 10 4 CFU mL −1 ) and incubated at 13 • 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 β-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 (H 2 O 2 ) 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 β-1,3-glucanase, as well as H 2 O 2 or O 2 − , may be involved in the enhancement of disease resistance in mango fruit.

Using jasmonates and salicylates to reduce losses within the fruit supply chain

“…A similar observation has been reported for mangos treated with SA and inoculated with Colletotrichum gloeosporioides [61]. This initial burst in H2O2 is considered to play the signalling role responsible for induced disease resistance [58,63,83,84] by enhancing the expression of PR genes and activity of defence related enzymes.…”

“…Higher phenolic content was also observed in loquat treated with MeJA at 10 µmol l -1 for 24 h, stored at 1 °C [17] and 20 °C [52], mangos treated with SA at 1000 µmol l -1 for 2 min, stored at 13 °C [61] and pomegranates treated with ASA at 100-1000 µmol l -1 for 10 min, stored at 2 °C [13]. Total phenolic content was also reported to be higher in peaches treated with MeJA at 1 µmol l -1 [47,48,63] stored at 0 °C, but not in their counterparts treated with MeJA at 100 µmol l -1 and stored at 5 °C [8].…”

“…Substantial increase in PAL activity has indeed been reported in several fruit pretreated with jasmonates or salicylates in response to infection with a pathogen during storage, e.g. in mangos treated with SA at 1000 µmol l -1 and inoculated with C. gloeosporioides [61], in loquat treated with MeJA at 10 µmol l -1 and inoculated with C. acutatum [52], in peaches treated with MeJA at 1 µmol l -1 and inoculated with P. expansum [63], in Chinese bayberries treated with MeJA at 10 µmol l -1 and inoculated with P. citrinum [58].…”

“…Postharvest treatments of fresh produce with jasmonates or salicylates have been found efficient in reducing decay in numerous products [18,22,24,28,37,49,50,52,[57][58][59][60][61][62][63] (Table 1). Significant reduction in decay was observed in grapefruit dipped in MeJA at 10-50 µmol l -1 for 30 s or treated with JA at 1-10 µmol l -1 and stored at 2 °C [19], whereas limited or no benefits, as indicated by only a slight reduction in lesion diameter, were observed in mandarins treated with MeJA at 10-200 µmol l -1 [64] and oranges treated with SA at 750-3000 µmol l -1 for 60 or 150 s [65], stored at 20 °C.…”

“…Another reason for Moscoso-Ramirez and Palou [65] not seeing any benefits of SA treatment in oranges inoculated with Penicillium digitatum and Penicillium italicum could be the time interval between the treatment and inoculation. These authors inoculated fruit either 24 h before the dipping in SA or 2-3 h after the treatment, whereas it has been demonstrated that SA can induce resistance against pathogens, but sufficient time is needed [19,52,60,61], so that the fruit can develop this resistance. It has been reported [66] that in pears it may take up to 48 and 72 h after the treatment with SA to develop disease resistance against Botrytis cinerea and Penicillium expansum, respectively.…”