Wound repair processes in fruit of the Cucurbita maxima hybrid ‘Delica’ and the role of scar tissue in the development of fungal rots on stored fruit

Abstract

Wound repair by fruits of the Cucurbita maxima hybrid ‘Delica’ involved the rapid sealing of the wound by a phloem exudate, which hardened on contact with air, and the development of a wound periderm and callus tissue beneath the layer of hardened exudate. Fruits which had stopped expanding at the time of wounding produced callus tissue in sufficient quantity to eventually rupture the wound periderm and expose the underlying tissue to colonisation by fungi. In rapidly expanding, young, fruits the growth of callus was relatively slight, the wound periderm remained intact, and the amount of scar tissue over the wound was much less than that which grew over wounds in older fruits. The scar tissue produced by the wound repair process, particularly in older fruit, increased the potential for subsequent invasion by fungal pathogens since rots occurred much more often at the edges of scar tissue than elsewhere on the fruit surface.

Keywords:

• Cucurbita maxima
• wound repair
• wound periderm
• fungal rots
• Buttercup squash ‘Delica’
• fruit anatomy