Conclusion
In summary, this study is the first to report that collapsedphloem tissue is the site of postharvest IB occurrence in pineap-ple fruit. The VB tissues had the highest activity of PPO and highestlevels of H2O2and phenolic compounds as detected by histologicalassays. A higher incidence of IB symptoms at the F/C in pineapplefruit may result from the relatively higher number of VBs and areduction in the relative amount of the protective sclerenchymafiber in the F/C region compared to other regions. A number ofthe VB at the F/C regions observed in pineapples classified as the‘Smooth Cayenne’ type was higher than that in the more suscepti-ble fruit of the ‘Queen’ group. The IB-resistant MD2 fruit had fewernumbers of VBs, but a higher number of sclerenchyma fiber layers,resulting in a larger VB size.