Molecular genetic variability of Juglans regia L. and Juglans sigillata D. as revealed by fluorescent amplified-fragment length polymorphism

Abstract

Juglans regia L. and J. sigillata D. have a long cultivation history in China. With the purpose of detecting interspecific and intraspecific genetic variation, 35 clonal cultivars of J. regia, J. sigillata, J. sigillata×J. regia and J. hopeiensis Hu. (J. mandshurica Maxim. ×J. regia) were selected from a broad geographic range and applied in amplified-fragment length polymorphism (AFLP) analysis. Clear-cut AFLP profiles were produced using 9 EcoR I/Mse I primer combinations. As for J. regia, J. sigillata and their hybrids, the percentages of polymorphic bands (PPBs) averaged 93.86%, 93.94% and 60.46%; the observed number of alleles (Na) averaged 1.5370, 1.6389 and 1.2593; the effective number of alleles (Ne) averaged 1.2582, 1.2543 and 1.1646; Nei's gene diversity (H) scored 0.1560, 0.1556 and 0.0951; Shannon’s information index (I) averaged 0.2402, 0.2459 and 0.1414, respectively. These results implied a moderate level of genetic diversity within the investigated species. The total gene diversity (Ht = 0.1596) can be distributed into intra- (Hs = 0.1356) and inter- (Dst = 0.0240) species gene diversity. The proportion of the distributed genetic diversity among populations (Gst ) was 0.1505, indicating that only 15% of the total gene diversity was attributed to differences between species. The factorial correspondence analysis (FCA) and unweighted pair-group method of arithmetic averages (UPGMA) analysis revealed a close genetic distance between these two species.