Variable distribution patterns of 5S (green) and 25S (red) rDNA sites among diploid Fragaria genotypes. Five cells (numbered 1-5) are selected from each of six diploid accessions, which show divergent distribution patterns of rDNA sites. Only chromosomes displaying (or "expected" to display) rDNA FISH signals are shown here (M: the medium-sized pair "single-marked" by 25S rDNA signals; S1: the small-sized pair "single-marked" by 25S rDNA signals; S2: the small-sized pair "double-marked" by both 25S and 5S rDNA signals in the typical pattern). The pattern represented by F. vesca 'Hawaii 4' here (A) is the typical one (6 = 2M+2S1+2S2) shared by most diploid Fragaria taxa, while distinctly divergent patterns are observed in very a few accessions shown in B. 5 = 2M+2S1+1S2 with an exception as 6 = 2M+2S1+2S2; C. 4 = 2M+2S1; D. 6 = 2M+2S1+2S2 with an exception as 5 = 2M+1S1+2S2; E. 5 = 2M+1S1+2S2; F. 4 = 2M+2S2. Within each of most accessions, the distribution pattern among cells is consistent, except for F. vesca 'Pawtuckaway' and F. iinumae. In F. vesca 'Pawtuckaway' (B), the S2 pair displays only one 25S rDNA signal in cells 1 to 4 but two signals in cell 5. In F. iinumae (D), the S1 pair exhibits two distinct 25S rDNA signals in cells 1 to 3, one distinct and one weak signal in cell 4, and only one signal in cell 5.