LAUSR

Abstract Cajal bodies (CBs) are nuclear domains widely present in eukaryotic cells. Their main functions include processing and modifications of small nuclear RNAs (snRNAs), including those participating in mRNA splicing. CBs are dynamic structures in terms of their mobility, fusion and split, which results in their variable number and size during cell cycle. CBs are supposed to play a role in response to various stresses or at least the cell reactions to these stressors is related with changing CB number and size. That is why the number and size of CBs were analyzed in primary root meristematic cells of soybean, a subtropical plant, whose seedlings were grown at 23 °C (the control), subjected to chilling stress (10 °C) and recovered at 23 °C after chilling. These parameters were examined in three classes of cell size which corresponded to the cells in G1, S and G2 phases. The general number of CBs in nuclei of the chilled plants was halved in comparison to the control cells, however this parameter returned to the control value during recovery. Such a result suggests that chilling may hinder formation of CBs or it may provoke their fusion. Moreover, the number of small CBs decreased and the number of large CBs increased during interphase progress, while the general number of CBs was constant in each treatment group. The constant number of CBs from G1 to G2 phase proves that in soybean cells they enlarge as a result of component accumulation rather than their fusion. The reasons of such a state of soybean CBs are discussed.