Development, Structure and Function of Secretory Trichomes in Psychotria Bacteriophila (Rubiaceae)

Abstract

Mucilage‐secreting dendroid trichomes develop from the adaxial epidermis of young stipules surrounding the shoot apex. Each trichome consists of a multicellular stalk from which radiate many branch cells. The trichome has no cuticle and the branch cell walls distally are loose cellulosic frameworks. Dictyosomes produce vesicles whose products are secreted through the plasma‐lemma and cell wall. Enlarged portions of the ER are frequently associated with dictyosomes and may be part of the system for synthesis and transport of secretion products. Bacteria, which later occur in leaf nodules, are present in the mucilage surrounding trichomes and young leaves. The latter develop stomata through which the bacteria enter. As stipules and leaves grow out of the apical region, the secretory trichomes degenerate and are replaced by non‐secretory ones.

Colleters in Caryocar brasiliense (Caryocaraceae) ontogenesis, ultrastructure and secretion

“…In C. brasiliense, proteins in colleter secretion were only detected qualitatively; however, the intensity of the reaction suggests that the quantity is small, with a possible enzymatic function. The presence of proteins in colleter secretion has also been reported by several authors (Horner & Lersten, 1968;Mohan & Inandar, 1986;Thomas & Dave, 1989); however, their function in protecting meristem apices still requires study.…”

Structure et ontogénie des nodules bactériens foliaires deI'Ardisia crenataSims (Myrsinaceae)

“…Chez Ardisia crenata leur structure comprend un petit pedicelle au sommet duquel s'etale un plateau cellulaire ramifie. En revanche, chez Psychotria bacteriophylla (Lersten & Horner, 1967 ;Horner & Lersten, 1968) le poi! secreteur comprend un axe principal unistratifie et pluricellulaire et des axes secondaires egalement unistratifies et pluricellulaires partant de chaque cellule de !…”

“…Le mecanisme de ! 'infestation a ete mis en evidence (Lersten & Horner, 1967 ;Horner & Lersten, 1968). Boullard (1990) signale chez les Myrsinaceae du genre Ardisia la presence de nodules foliaires submarginaux regulierement repartis dans les sinus de la marge limbaire crenelee.…”

Sur l'expression ultrastructurale de la differenciation des cellules vegetales.

“…Les trichomes secreteurs des stipules de Psychotria bacteriophila Les points vegetatifs de Psychotria bacteriophila sont proteges par les stipules soudes. La face interne du capuchon stipulaire est tapissee de poils secreteurs ra mifies qui produisent un mucilage riche en proteines qui abrite des bacteries symbiotes (Horner et Lersten 1968).…”

“…L'appareil reticulaire communique largement avec le periplasme et les proteines, emises a l'exterieur de la cellule, s'associent aux polysaccharides du mucilage (Horner et Lersten 1968) pour realiser un veritable milieu de culture solide pour les bacteries symbiotes.…”