engleski

Spatial genetic structure of Hordeum chilense Roem. & Schult. as revealed by AFLP markers

Hordeum chilense Roem. & Schult. is a native South American diploid, perennial, wild barley included in the section Anisolepis Nevski of the genus Hordeum in the Triticeae tribe. H. chilense is readily crossed with wheat, rye and also cultivated barley, what confers it a high potential as a bridge to transfer favourable traits to cultivated cereals. However, owing to the desertification process, H. chilense is gradually disappearing from some of its native environments. Sixty-five accessions of H. chilense were collected from six regions in Chile covering nearly complete distribution area of the species. Genetic differentiation among regions and spatial genetic structure were analyzed by amplified fragment length polymorphisms (AFLPs). The analysis of molecular variance (AMOVA) indicated significant genetic differentiation among regions, although most of the variability (66.66 %) was attributable to variation within regions. Pairwise geographic distances between individuals were calculated from the passport data and ten geographical distance classes were created in such a manner that the number of pairwise comparisons in each distance class was approximately the same. The spatial autocorrelation was tested using three methods suitable for dominant marker data: (1) the standardized Mantel statistics, (2) autocorrelation index for DNA analysis (AIDA) II, and (3) genetic distogram. All the methods yielded essentially the same results. For the first four distance classes (from 0 to appr. 200 km) the spatial genetics coefficients (Mantel's r, AIDA's II, dk) were found significant indicating the existence of spatial autocorrelation. Nevertheless, the geographically most distant pairs formed mainly by accessions from the most northern region (no. 1) and from the most southern regions (nos. 5 and 6) were genetically far more similar than it could be expected by isolation-by-distance hypothesis. Taking into account the responsible environmental and biological factors, selection of appropriate management and conservation methodologies will be discussed.

Hordeum chilense; spatial genetics; isolation-by-distance; AFLPs

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