Radioautographic visualization of incorporation of lipid precursors into anthers of Muscari comosum (L.) Mili.

Abstract

Incorporation of the following lipid precursors: DL-mevalonic acid-2 <sup>3</sup>H, <sup>3</sup>H palmitic acid and acetic acid-<sup>3</sup>H sodium salt, into the anther cells of <i>Muscari comosum</i> (L.) Mili. has been investigated. These lipid precursors have been demonstrated to incorporate into pollen mother cells, pollen grains and the tapetum at the consecutive developmental stages. Ali used isotopes are incorporated into the cytoplasm of these cells and in the case of pollen grain the radioactivity of pollen grain wall (mainly composed of sporopellenin) is noticed. The highest radioactivity of pollen grain wall is observed after acetic acid, the lower one after palmitic acid, whereas the lowest uptake of lipid precursor occurs after mevalonic acid. In comparison with tetrad stage the distinct inrease of the cytoplasmic radioactivity of tapetum, which appears to1 accompany the labelling of pollen grain wall, seems to indicate the participation of tapetum in the formation of exine. A possible role of Ubisch bodies in the formation of pollen grain wall is discussed.