ИСТИНА

In Apiaceae, the length of the psbA-trnH region varies greatly and the predom- inant events in the evolution of the spacer appear to be length mutations. The reduction in size is due mainly to the deletion in 3′ region of spacer. Comparing to other Apiaceae, the maximum reduction in length (110Ђ120 bp) was observed in the geophilic (eastern Bunium species, Elaeosticta, Galagania, Gongylotaxis, Hyalolaena, Mogoltavia, and Oedibasis) and not geophilic (Kosopoljanskia, Lip- skya, Schrenkia, Schtschurowskia, and Sclerotiaria) taxa distributed in Middle Asia. These two lineages are sister in the internal transcribed spacer (ITS) tree and form strongly supported clade. However, many sequence variations in psbA- trnH spacer are probably homoplastic. The diЁerences in nucleotide sequences can be accounted for mainly by inversions and can independently occur in unre- lated lineages (see, e. g., [1]). Besides, similar nucleotide substitutions were found in some Bunium, Elaeo- sticta, Hyalolaena, Kosopoljanskia, and Screnkia species. Analysis of the spacer secondary structure suggests that these substitutions resulted in stabilizing the stem-loop region of the 5′ spacer end. Stem length compensations via substi- tution in the 5′ end of spacer were revealed in various angiosperm genera (see review in [2]). The present study is the ¦rst, however, to demonstrate the inde- pendent appearance of identical sequence complementarities (traits) necessary to stabilizing the stem-loop structure in diЁerent lineages. Noteworthy, other nucleotide substitutions less aЁecting stability of the spacer stem-loop structure mark distinct phylogenetic clades supported with nuclear ITS data.