Abstract: Genetic DNAs from ‘Shixia’ longan (Dimocarpus longana Lour. ) and its sport line which could generate larger fruits containing sweet osmanthus flavour were amplified by RAPD with 160 10 bp single and mixed random primers to study the genetic substance change of the sport. Six single and fourmixed primers were screened which could produce stable polymorphic segments between the two clones. 13 out of the total 99 fragments amp lified were distinctive including the loss of a normal segment and appearance of a new one.The polymorphic fragments amplified were S71-560, S161-813, Z70-800, etc. The difference of amplified DNA segments showed that the large fruit and sweet osmanthus mutant was closely related to changes of some genetic substances in the sport line. Further studying also showed that the genotype of the sport could be inherited stablely by way of asexual propagation. The polymorphic segments could be used to forecast the fruit characters of the grafted seedlings from the sport scion.

Key words: Longan, Dimocarpus longana, Sport, RAPD