The outer skin layer in any plant is essential in offering a protective barrier against water loss and pathogen attack. Within fleshy fruit, the skin supports internal cell layers and can provide the initial cues in attracting seed-dispersing animals. The skin of a fruit, termed the exocarp, is a key element of consumer preference and a target for many breeding programs. Across fruiting species there is a huge diversity of exocarp types and these range from a simple single living cell layer (epidermis) often covered with a waxy layer, to complex multicellular suberised and dead cell layers (periderm), with various intermediate russet forms in between. Each exocarp can be interspersed with other structures such as hairs or spines. The epidermis has been well characterised and remains pluripotent with the help of the cells immediately under the epidermis. The periderm, in contrast, is the result of secondary meristematic activity, which replaces the epidermal layers, and is not well characterised in fruits. In this review we explore the structure, composition and mechanisms that control the development of a periderm type fruit exocarp. We draw upon literature from non-fleshy fruit species that form periderm tissue, from which a considerable amount of research has been undertaken.

任何植物的外皮层对于提供防止水分流失和病原体侵袭的保护性屏障都是必不可少的。在果肉中，皮肤支持内部细胞层，并可以在吸引散布种子的动物中提供初始线索。被称为外果皮的水果皮是消费者偏爱的关键要素，也是许多育种计划的目标。在各种结果物种中，外果皮类型种类繁多，从简单的单个活细胞层（表皮）（通常被蜡质层覆盖）到复杂的多细胞浸没和死细胞层（皮层），以及介于两者之间的各种中间红褐色形式。 。每个外果皮都可以穿插其他结构，例如头发或刺。表皮已被很好地表征，并在表皮下面的细胞的帮助下保持了多能性。相反，周皮是次生分生组织活动的结果，它代替了表皮层，并且在水果中没有很好地表征。在这篇综述中，我们探讨了控制果皮型果实外果皮发育的结构，组成和机制。我们从形成皮周组织的非肉质水果物种中汲取了文献资料，从中进行了大量研究。