ABSTRACT
Phylogenetic relations between plants are less well known than those between animals. This chapter discusses the available data on the structure and evolution of low molecular weight ribosomal RNAs (rRNA), which we designate as 23 small size rRNA-derived; it includes 5.8S rRNA from eukaryote cytosol and 4.5S rRNA from chloroplast ribosomes. The thorough comparisons of such characters may help not only in elucidation of phylogeny, but also in producing an insight into rRNA structure-function relationships. Besides the above-mentioned cases of the disturbance of normal splicing during large size rRNA maturation, resulting in the appearance of new components and evolutionally established in large phylogenetic lines, similar situations have also been observed only in individual species. Hybridization of chloroplast DNA makes it possible to compare less similar species from diverse angiosperm orders. The organization of the ribosomal operon has been studied in dozens of eukaryotic species.
