HISTOCHEMISTRY AND COMPOSITION OF THE CELL-WALLS OF STYLES OF NICOTIANA-ALATA LINK ET OTTO

The cell walls of styles of Nicotiana alata Link et Otto (ornamental t obacco; Solanaceae) were analysed chemically and examined histochemica lly. Cell-wall preparations were obtained from whole styles and from i solated transmitting-tissue cells. The style epidermal cells were show n histochemically to have thick, lignified secondary walls. These wall s probably constituted a large proportion of the cell-wall preparation from whole styles as analysis of whole-style walls indicated that the major polysaccharides were xylans and cellulose, which are typical of lignified secondary walls of Magnoliopsida (dicotyledons). Lignificat ion of the style epidermal walls was also demonstrated histochemically in 10 other species (5 genera including Nicotiana) of the sub-family Cestroideae of the Solanaceae, but not in 15 species (9 genera) of the sub-family Solanoideae of the Solanaceae, nor in 3 other species of d icotyledons and 2 species of Liliopsida (monocotyledons). Analysis of the cell-wall preparation from isolated transmitting-tissue cells of N . alata indicated that these contained cellulose, xyloglucans, and pec tic polysaccharides, which is typical of primary cell walls of dicotyl edons. However, the analysis indicated that the walls also contained a n unusually high proportion of Type II arabinogalactans. Staining of t he transmitting-tissue cell-wall preparation with beta-glucosyl Yariv reagent, a histochemical reagent specific for arabinogalactan proteins , confirmed their presence, which may be related to the role of these cells in secreting the stylar extracellular matrix.