Ultrastructural and Chemical Evidence That the Cell Wall of Green Cotton Fiber Is Suberized

Green cotton (Gossypium hirsutum L.) fibers were shown by electron microscopy to have numerous thin concentric rings around the lumen of the cell. These rings possessed a lamellar fine structure characteristic of suberin. LiA1D(4) depolymerization and gas chromatography-mass spectrometry analysis showed the presence of a suberin polymer in the green cotton with the major aliphatic monomers being omega-hydroxydocosanoic acid (70%) and docosanedoic acid (25%). Ordinary white cotton was shown by chemical and ultrastructural examination to be encircled by a thin cuticular polymer containing less than 0.5% of the aliphatic components found in green cotton.