Morphological and chemical characteristics of the warty layer in red pine (Pinus resinosa Ait.)

Abstract

Red pine (Pinus resino.wAit.) specimens were successively treated in the following manner: boiled in water for 2 hours, extracted with alcohol-benzene for 4 hours, extracted with 5% NaOH aqueous solution for L hour, and delignified with acidified sodium chlorite for 1 hour.The ultnstructure of the wany layer was studied after each sequence of treatment.It was found that the lumen surface of . .red pine tracheids was relatively free of encrustation.The microfibrils in the surface lamella of the S3 laver were deoosited in a bundle form.Two twes of warts were found in red pine tracheids.The first . .type of wans was localized thickenings of the S3 microfibrillar bundles, and the second type of wans was those situated at the end of micmfihrillar bundles.Results of studying the effect of chemical treatments suggested that the encrustant lining the lumen wall was hemicellulose in nature and that the warts were made up of a combination of lignin and hemicelluloses.A possible mechanism of the formation of the last lamella of the S3 layer and the associated warts is also discussed.