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United States Department of Agriculture

Agricultural Research Service

Title: Oil Red As a Histochemical Stain for Natural Fibers and Plant Cuticle

Authors
item Akin, Danny
item Rigsby, Luanne
item Morrison Iii, Wiley

Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 25, 2003
Publication Date: April 1, 2004
Citation: AKIN, D.E., RIGSBY, L.L., MORRISON III, W.H. OIL RED AS A HISTOCHEMICAL STAIN FOR NATURAL FIBERS AND PLANT CUTICLE. INDUSTRIAL CROPS AND PRODUCTS. VOL. 19. P. 119-124. 2004.

Interpretive Summary: Biobased fibers such as flax must be retted to separate fibers from the non-fiber components, such as cuticle. A useful histochemical method was not available to quickly identify the cuticle in retted materials. Scientists at the Russell Research Center used a wax stain, Oil Red, to specifically stain and thereby identify flax cuticle as an aid to identify contaminants in retted, cleaned flax fibers. Further tests on other plants, including cotton fibers, showed the general usefulness of Oil Red to stain cuticle in a variety of plants. The value of this work is that a new histochemical stain has been developed to the identify contaminants in bio-based fibers and that has a widespread application in plant sciences.

Technical Abstract: Oil Red was evaluated as a histochemical stain for the cuticle of plants and for components in cotton and flax fibers. A positive reaction for arachidyl stearate and as well as differential staining of plants after sequential extraction of fatty acids and alcohols confirmed that Oil Red stained wax components in plant materials. For cotton (Gossypium hirsutum) fibers, Oil Red stained to a greater extent the regions closest to the seed coat, especially at points where fibers attached to the seed coat. Fiber regions at a distance from the seed coats stained sporadically, suggesting the wax was unevenly distributed. Flax (Linum usitatissimum) bast fibers, in contrast, did not stain with Oil Red, but the protective stem cuticle was intensely stained. The positive histochemical reaction for cuticle identified non-fiber fragments in processed and cleaned flax fibers, thus providing a quick method to visually detect trash components in fiber and products. Likewise, bast fibers from kenaf (Hibiscus cannabinus) did not stain well with Oil Red, whereas the stem cuticle gave a positive reaction. The general usefulness of Oil Red as a histochemical stain for the plant cuticle was demonstrated in leaves and stems of mature corn (Zea mays) and fresh bermudagrass (Cynodon dactylon) leaves. Oil Red provides a quick, qualitative histochemical method to demonstrate the wax-containing cuticle in plants.

Last Modified: 10/24/2014
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