Proportional increase of rDNA site number in lower (3x -
6x) polyploid strawberries
The triploid cytotype of the hybrid F. ×bifera was previously
inferred to possess one copy of the F. vesca genome
and two copies of the F. viridis genome [12]. Three
5S and nine 25S rDNA sites observed in this triploid
cytotype constitute simple multiples of both rDNA site
numbers in its two diploid progenitors. The one larger
and stronger 5S rDNA site is probably from F. vesca,
while the two smaller ones are from F. viridis, in consideration
of the copy number of subgenomes provided by
the two donors.