The ultrastructural of the interphase cell nucleus of Lacandonia schismatica (Lacandoniaceae: Triuridales) reveals a non-typical extranucleolar pArtículo de investigación

Abstract

By light and electron microscope cytochemistry we characterized the interphase nucleus of Lacandonia schismatica, the only known species of the new plant family Lacandoniaceae, whose most peculiar feature is the inverted position of the sexual organs, an aspect never found before among flowering plants. Furthermore, we compare it to Triuris alata, a related species, to Voyria aphylla (a dicotyledon), to Gymnosiphon divaricatus (a monocotyledon) and also to saprophytes. The reticulated chromatin of L schismatica and T alata is similar to that of other monocotyledons. In addition, we describe a unique type of RNP granules in the interchromatin space which are about 32 +/- 3 nm SD in diameter and occur as huge clusters. They are intermediate in size and spatial distribution between inter- and peri-chromatin granules. We term them 'Lacandonia granules'. The granules were also found in T alata. They are 31 +/- 2 nm in diameter. No significant differences in size were observed between them (P > 0.05). Synaptonemal-like complexes and ring-shaped structures were seen in interphase nuclei of somatic cells of these species. Coiled and nucleolus-associated bodies, as well as centromeres were also found in these two organisms. On the contrary, V aphylla and G divaricatus display a chromocentric nuclear organization. The nuclear similarities between L schismatica and T alata suggest extremely close phylogenetic relationships between them.