Abstract:

Haloxylon ammodendron (CA Mey.) Bunge, the dominant tree species in many xerophytic deserts of Asia, plays an important role in the maintenance of the structure and function of these ecosystems. Despite its ecological and economic importance, nearly nothing is known about its genetic attributes. In this study, RAPD and ISSR markers were used to investigate the genetic diversity and structure of four natural populations of H. ammodendron. Five RAPD primers amplified 61 bands with 51 (83.6%) polymorphic and eight ISSR primers amplified 195 bands with 175 (89.7%) polymorphic. The genetic diversity, estimated by Shannon’s index, was 0.333 (by RAPDs) and 0.367 (by ISSRs). Both RAPD and ISSR analyses revealed a high level of genetic diversity in natural populations of H. ammodendron. Furthermore, analysis of molecular variance (AMOVA) was used to apportion the variation within and between populations. The proportion of variation attributable to within-population differences was very high (138.2% by RAPDs; 89.4% by ISSRs). No genetic differentiation was detected among populations using RAPDs (P = 0.999), while only a small amount of variation (10.6%) was detected among populations using ISSRs. We suggest that the present genetic structure is due to high levels of gene flow.

Key words: Haloxylon ammodendron, RAPD, ISSR, genetic structure, gene flow