The Multiple Epidermis-Cuticle Complex of Medlar Fruit Mespilus germanica L. (Rosaceae)

Abstract

In order to determine the authenticity of the multiple epidermal layers in the pomaceous fruit of Medlar or Mespil (Mespilus germanica L.), developmental studies were made from 2 weeks before anthesis through harvest and storage. Various histochemical techniques were used for the determination of epidermal cell wall structures and cell contents, and for the isolation and study of the cuticular membranes. The multiseriate epidermis is derived from successive tangential divisions of the initially uniseriate epidermis commencing about 3 weeks post-anthesis. The divisions occur simultaneously around the fruit circumference and result in the formation of a normally four- to five-layered epidermis at fruit maturity. As each epidermal layer is derived it concomitantly develops a distinct, flanged cuticle that remains persistent until sloughing of the layer occurs. Evidence provided by light and scanning electron microscopy indicates the presence of discrete ubiquitous pores and non-anastomosing, anticlinally oriented canals in the cuticular membranes. Measurements were made of individual cuticular membrane thicknesses during development, and of cuticular pore dimensions in the mature fruit; cuticular pore numbers were calculated. A brief study was made of the relationship between lenticel development and development of the multiseriate epidermis.