XVI International Botanical Congess

In early-spring ephemeral Corydalis bracteata growing outdoors and replaced to greenhouse for 7 days and in summer-vegetating Corydalis ochotensis ultrastructure of nucleolus was studied morphometrically. C. bracteata growing outdoors has large cells, nuclei and nucleoli. Absolute volume and volume density of granular component are greater and nucleus/nucleolus ratio and nucleolus- ssociated chromatin volume in C. bracteata are less than in C. ochotensis. Nucleolus structure changes significantly and becomes similar to that one of summer-growing C. ochotensis after C. bracteata plants were moved to greenhouse, nucleoli are less active judging from the structure. Maintenance of sufficiently high nucleolar activity in spite of cold inhibition of biochemical reaction rates is possibly biological role of increasing of nucleolar volume, its granular component and ribosome number in early-spring ephemerals.