RAPD inheritance and diversity in pawpaw (Asimina triloba)

Twelve, Ill-base primers amplified a total of 20 intense and easily scorabl e poly-morphic bands in an interspecific cross of PPF1-5 paw-paw [Asimina t riloba (L,) Dunal.] x RET (Asimina reticulata Shuttlew,), In this cross, al l bands scored were present in, and inherited from, the A. triloba parent P PF1-5, Nineteen of the 20 bands were found to segregate as expected (1:1 or 3:1) based on chi-square goodness-of-fit tests,and were subsequently used to evaluate genetic diversity in populations of A. triloba collected from s ix states (Georgia, Illinois, Indiana, Maryland, New York, and West Virgini a) within its natural range. Analysis of genetic diversity of the populatio ns revealed that the mean number of alleles per locus was A = 1.64, percent polymorphic loci was P = 64, and expected heterozygosity was H-e = 0.25, N o significant differences were found among populations for any of the polym orphic indices. Partitioning of the population genetic diversity showed tha t the average genetic diversity within populations was H-s = 0.26, accounti ng for 72 % of the total genetic diversity. Genetic diversity among populat ions was D-st = 0.10, accounting for 28 % of the total genetic diversity, N ei's genetic identity and distance showed a high mean identity of 0.86 betw een populations. Genetic relationships among the populations examined by un weighted pair-group mean clustering analysis separated the sis populations into two primary clusters: one composed of Georgia, Maryland, and New York, and the other composed of Illinois, Indiana, and West Virginia. The Georgi a and Indiana populations were further separated from the other populations within each group. This study provides additional evidence that marginal p opulations within the natural range of A. triloba should be included in fut ure collection efforts to capture most of the rare and local alleles respon sible for this differentiation.