Amplification of target SSRs present in isolated PstI–MseI fragments using primer pairs specific to the conserved DNA sequences flanking the microsatellite repeats. The primer pairs used in each reaction are from left to right: sun24, sun25, sun26, sun27, sun28, sun29, sun30, sun31, sun32, sun33, sun34, sun35 and sun36. A 25 bp DNA ladder (Gibco BRL) was used as a size marker.