Abscisic acid induces differential expression of genes involved in wound-induced suberization in postharvest tomato fruit

Fruit wounding occurred at harvest and transportation requires rapid suberization as a major part of the healing process to prevent infection and desiccation. The focus of this work was to explore the mediation of abscisic acid (ABA) on wound-induced suberization and to determine expression profiles of specific genes involved in wound-induced suberization in tomato fruit. The measurements of weight loss and fruit firmness suggested wound-induced suberization started at 2 d after wounding. The suberization process with the accumulation of suberin polyphenolics (SPP) and polyaliphatics (SPA) observed through autofluorescence microscopy and Sudan IV staining was accelerated by ABA. Expressions of SlPAL5 and Sl4CL involved in the synthesis of SPP reached the highest at 4 and 8 d after wounding following ABA application, respectively. Associated with SPA biosynthesis, SlLACS1 and SlLACS2 showed the most abundant transcripts at 8 and 6 d in ABA group, respectively. Transcript levels including SlKCSs, SlCYP86B1, SlFAR3, and SlGPATs were up-regulated at 2 d after wounding by ABA. Activities of polyphenol oxidase and lipoxygenase were also enhanced during wound-induced suberization following ABA application. The results in this study proved that ABA accelerated the wound-induced suberization progress by increasing the transcript levels of relevant genes in postharvest tomato fruit.