Segregation of RAPD Markers: A Case in Interspecific Cross of Eucalyptus

Seven 10 mer primers were used for analysis on segregation of RAPD(Random amplified polymorphic DNA) markers in an interspecific F 1 population of Eucalyptus urophylla × E. tereticornis, including 2 parents and 212 sibs. Of the total 40 fragments amplified, 28(70%) were polymorphic between parents and 24(60%) segregant in the sibs, indicating a high level of polymorphism and heterozygosity at RAPD loci between the two parents. There were 27 markers segregating in a Mendelian pattern, including 9 markers presenting in both parents and all sibs(representing a genotypic combination AA×AA, AA×Aa or Aa×AA),7 markers polymorphic between the parents but homologous in all sibs(AA×aa or aa×AA),2 markers presenting in both parents and segregating in the sibs in a ratio 3∶1(Aa×Aa), and 9 markers polymorphic between the parents and segregating in the sibs in a ratio 1∶1(Aa×aa or aa×Aa). There were 13 markers segregating in a nonmendelian pattern, including 12 markers polymorphic between parents but segregating in the sibs in a ratio distortive from 1∶1, and 1 markers homologous in both parents but segregating in the sibs in a ratio distortive from 3∶1. Those markers that were polymorphic between parents and segregating 1∶1 in the sibs, following a pseudo testcross configuration, could be potentially useful for genetic linkage map construction of the representative species, which would lay a theoretical basis for genetic linkage map construction using RAPD markers and F 1 population.