Developmental Ultrastructure of Glandular Trichomes of Rosmarinus officinalis: Secretory Cavity and Secretory Vesicle Formation

Abstract

Glandular trichomes in the leaf lamina of Rosmarinus officinalis L. were examined by scanning and transmission electron microscopy. The leaves were characterized by an abundance of two types of glandular trichomes-small capitate and large peltate glandular trichomes. In addition to the glandular trichomes, numerous non-glandular trichomes were present on the abaxial surface of the leaf. These trichomes mainly predominated on the midrib, whereas glandular trichomes occurred on non-vein areas. At the initial phase of secretory cavity formation, hyaline areas were abundant in periclinal walls of head cells, while they were not observed in the anticlinal walls. The hyaline areas gradually increased in size, fusing with other areas throughout the wall. Loose wall material adjacent to hyaline areas was released from the head cell walls and migrated into the secretory cavities. As the secretory cavities continued to enlarge, the new vesicles emerging into the secretory cavities from the walls of head cells became surrounded with the surface of a typical membrane. They developed a round shape, but the contours of the vesicle surfaces appeared polygonal when tightly packed inside a cavity. These vesicles varied in size; small vesicles often possessed electron-dense contents, while large vesicles contained electron-light contents.

Partial propane extraction of aromatic compounds from dehydrated basils (Ocimum Lamiaceae)

“…4 Aromatic compounds are reportedly produced and stored in various types of glandular trichomes (glands) located on the surfaces of the aerial parts of members of the Lamiaceae plant family, especially the leaf and floral structures. 26,27 Gland form and susceptibility to rupture during extraction apparently delineate aromatic compound yield, especially for intact leaves and flower structures such as those used in our study. We observed that 'Blue Spice' contained hair-type glands present through all the aerial parts, including stems.…”

Morphogenesis and developmental ultrastructure of Nicotiana tabacum short glandular trichomes

“…Membrane bound vesicular structures of various sizes found in the vacuoles of tobacco trichomes at this later stage (Figure a, c) appeared to arise in a process similar to inward blebbing of the cytoplasm into the vacuole observed during PCD in Zea mays cortex cells during root aerenchyma formation (Schussler & Longstreth, ). Vesicular structures present in the vacuole and extraplasmic space of tobacco short GTs greatly resembled secretory vesicles aggregating in the secretory cavities of GTs of Rosmarinus officinalis (Choi et al, ). In R. officinalis , numerous round‐shaped secretory vesicles were surrounded by membranes with fibrillar material and possessed dense or loose contents, where small vesicles had more electron dense contents and the large ones appeared more electron light, similarly to those found in tobacco.…”

Glandular Trichomes on the Leaves of Nicotiana tabacum: Morphology, Developmental Ultrastructure, and Secondary Metabolites

“…Capitate trichomes consist of a basal cell, a one-to several-celled stalk, and a head of usually one or two cells. There are various types of capitate trichomes, which differ significantly in both structure and size [24,[35][36][37][38].…”

“…8f). Membranous vesicles present in the periplasmic space greatly resemble secretory vesicles associated with abundant electron-dense secretions of secretory cells [4,13,37]. From the outer side of the cuticle, which is less electron dense than the inner part, osmiophilic fibrous material is released (Fig.…”