Morphological Classification of Trichomes Associated with Possible Biotic Stress Resistance in the Genus Capsicum

Abstract

Trichomes are specialized epidermal structure having the functions of physical and chemical block against biotic and abiotic stresses. Several studies on <TEX>$Capsicum$</TEX> species revealed that virus and herbivore resistance is associated with trichome-formation. However, there is no research on the structural characterization of trichomes developed on the epidermis of <TEX>$Capsicum$</TEX> spp. Thus, this study attempts to charaterize the trichome morphologies in 5 species of <TEX>$Capsicum$</TEX> using a Field Emission Scanning Electron Microscopy (FESEM). Six main trichome types were identified by their morphology under FESEM. Both glandular and non-glandular types of trichomes were developed on the epidermal tissues of <TEX>$Capsicum$</TEX> spp. The glandular trichome were further classified into type I, IV and VII according to their base, stalk length, and stalk. Non-glandular trichomes were also classified into type II, III, and V based on stalk cell number and norphology. Almost all the species in <TEX>$C.$</TEX> <TEX>$chinense$</TEX> and <TEX>$C.$</TEX> <TEX>$pubescens$</TEX> had glandular trichomes. To our knowledge, this is the first study on classification of trichomes in the genus <TEX>$Capsicum$</TEX> and, our results could provide basic informations for understanding the structure and function of trichomes on the epidermal differentiation and association with biotic stress tolerance.