Nucleolus-associated bodies in meristematic cells of two plant species (Cicer arietinum and Leucaena glauca) with different ploidy levels

Abstract

Light microscopy has shown that plant interphase nuclei contain small, roundish bodies, some of which may be closely associated with the nucleolar surface. Serial sections were used to determine the location, size, and number of these nucleolus-associated bodies in two plant species having different ploidy levels. In Cicer arietinum, a diploid species, one or two such bodies were observed, whereas in Leucaena glauca, an octoploid species, four to six nucleolus-associated bodies were present. At the ultrastructural level, these bodies consistently exhibited a distinct fibrillogranular texture and were located close to segments of the interphase nucleolar organizer track, a meandering, coarse, filamentous structure particularly well developed within many plant species and known to consist partly of chromatin. The fact that the number of these bodies closely matches that of the satellite-bearing metaphase chromosomes suggests that they may represent terminal segments of the nucleolar chromosomes. Other equally plausible interpretations of the nature of the NABs are also considered. Key words: plant interphase nucleus, nucleolus-associated bodies, satellites.