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Cytogenetic variation in populations of Armeria maritima (Mill.) Willd. in relation to geographical distribution and soil stress tolerances

par Coulaud, Joëlle;Barghi, Nasrine;Siljak-Yakovlev, Sonja;Lefebvre, Claude
Référence Canadian Journal of Botany, 77, 5, page (673-685)
Publication Publié, 1999

Article révisé par les pairs

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Résumé :

Ten Armeria maritima (Mill.) Willd. populations (2n = 18) from contrasting ecogeographic situations were compared using 30 morphometric characters of karyotype and frequencies of abnormal metaphase and interphase cells in root-tip meristems. Despite the general symmetry and similarities, karyotypes of populations can be distinguished using a set of precise karyotypic features. Variations within populations mainly concerned the occurrence of satellites and weakly condensed areas of chromosomes. Total chromosome length measurements were congruent with flow cytometry estimates of DNA amounts. The geographical differentiation of European population karyotypes is in accordance with previously defined biochemical clustering. One population from Germany (ssp. bottendorfensis) is more similar to the American population (ssp. californica) than to the other European populations. Proposed trends of karyotype evolution are discussed in comparison with previous results on other character sets and taxonomic treatments. The species karyotype seems particularly unstable, as chromosome' strong links at mitosis cause breaks generating chromosomal mutations and aneuploidy at the intra-individual level in all the populations. Abnormal interphase cells were found in most of the populations but were especially frequent in heavy-metal tolerant populations. The highest frequencies of karyotype aberrations were found in the American population and in populations adapted to soils with high levels of heavy metals or salinity. The frequency of interphase aberrations appeared to be related to the mean level of heavy-metal tolerance of populations. Consequently, the two types of abnormalities may originate from independent mechanisms. The genome behaviour of A. maritima is discussed with reference to recent findings concerning the effects of soil toxicity on plant genomes.