New approaches for studying and exploiting an old protuberance, the plant trichome

Abstract

Background and aims: Much recent study of plant trichomes has focused on various aspects of glandular secreting trichomes (GSTs) and differentiation of simple trichomes. This Botanical Briefing will highlight: research on various aspects of, and manipulation of glandular secreting trichomes; molecular aspects of the differentiation and development of simple trichomes of arabidopsis and cotton; how methods for manipulation of model systems used in the above work can be applied to expand our understanding of less studied surface structures of plants.

Scope: The Briefing will cover: established and suggested roles of simple and glandular secreting trichomes; recent results regarding solute and ion movement in trichomes; methods for isolating trichomes; recent studies of trichome differentiation and development; attempts to modify metabolism in secreting trichomes; efforts to exploit trichomes for commercial and agronomic purposes.

Fig. 1. A, Nicotiana tabacum leaf surface showing exudate laden GSTs and simple trichomes ×110. B, N. tabacum hydathode ×700. C, N. tabacum GST glands with exudate removed, pretreated with 5 % HOAc then silver nitrate–rubeanic acid to stain calcium oxalate crystals ×560. D, N. tabacum GST glands, treated as in C, but first pretreated with 0·25 m HCl to disolve calcium oxalate ×560. C and D by Vogeli‐Lange and Wagner, unpublished.

Fig. 2. A, Nicotiana tabacum GSTs after treatment with rhodamine B to stain sucrose esters of exudates. B, Top view of rhodamine B‐treated leaf showing migration of stained exudate to the base of trichomes, then out onto the epidermal surface. C, Aphid walking on a rhodamine B‐treated leaf, note exudate on the legs. D, Fluorescence micrograph of aphid after it had walked on a rhodamine B‐treated leaf for 1 min. Yellow fluorescence denotes highest stain accumulation. Control aphids show no autofluorescence.

Fig. 3. Leaf pit on the abaxial leaf surface of oleander. The inner surface of the pit is lined with stomata and the opening with simple trichomes that are thought to reduce water loss in this highly drought‐resistant plant. Photographs by Jack M. Bostrack/Visuals Unlimited. Reproduced with permission of H. W. Freeman and Co.