Effect Of Abscisic Acid On Postharvest Wound-healing Process Of Tomato Fruit

Fresh fruit often suffer mechanical wounds during harvest, transportation and storage. Physical wounding is an important abiotic stress that can significantly compromise fruit quality and shelf life and also elicit a series of physiological and pathological responses. Therefore, rapid wound-healing is critical for postharvest fruit. Tomato fruit were treated under vacuum after wounding with ABA, fluridone (FLD) and deionized water (Control), respectively. The effect of abscisic acid (ABA) on wound-healing, phenolic compounds, enzyme activities, suberin and related genes in postharvest mature green cherry tomato fruit was investigated in this study.Mature-green cherry tomato fruit were used in this experiment. After wounding at equator with a sterilized scalpel, fruit were immersed in 10-3 M ABA,10-4 M FLD and deionized water (control) under vacuum (0.07 MPa,5 min), respectively. Treated fruit were allowed to wound-heal at 20? and 90% relative humidity in the dark. The vacuuming conditions and concentrations of ABA and FLD were based on results from preliminary experiments. The indexes were determined in wound tissues every day and the results showed as follows:1. Weight loss and MDA content were reduced in ABA-treated tomato fruit compared with the control. ABA promoted wound-healing process by enhancing total phenol and flavonoids contents as well as phenylalanine ammonia-lyase (PAL), superoxide dismutase (SOD) and catalase (CAT) activities in wound tissues of tomato fruit. FLD treatment, however, had the opposite effects. In conclusion, ABA promotes the synthesis of phenolic compounds during wound-healing in postharvest tomato fruit.2. ABA group exhibited an increase in the intensity and cell layers of autofluorescence and Sudan IV histochemical dye especially at 3-4 d after wound-healing while FLD group depicted a reduced intensity in comparison with the control. Suberin components were accumulated significantly along with increased activities of PAL and peroxidase (POD). PAL activity increased after wounding, reached the maximum at the third day and then decreased, while POD activity decreased after wounding and then increased in all groups during wound-healing. PAL and POD activities were enhanced by ABA application while inhibited by FLD treatment compared with the control. In summary, ABA promotes wound-healing process by accelerating suberin synthesis in postharvest tomato fruit.3. In comparison with the control, the genes (CD1?Cer6?Tas14?TPX1?Tswl2? X14449) related with wound-healing in tomato fruit were up-regulated and down-regulated in ABA and FLD group, respectively. What's more, ABA advanced the peak of relative gene expressions. Consequently, ABA promotes the expression of genes in tomato fruit during wound-healing.