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Haumaniastrum katangense and Crepidorhopalon tenuis are two cuprophytes characteristic of the Katangan Copper Belt flora. We have studied the endophytic bacteria of H. katangense and C. tenuis as a first step to evaluate their potential contribution to plant adaptation to copper excess. Although their number varied considerably from sample to sample, culturable bacteria were found in roots and shoots of most plants. More than 800 isolates were screened for each plant species. Identification of isolates based on the sequence of the 16S rRNA gene, allocated them to 31 taxonomic units, belonging to 17 genera, mainly Proteobacteria. A great proportion of the bacteria were cupro-resistant and often resistant to other metals, especially zinc and cobalt, as well as nickel for the Methylobacterium isolates. Direct PCR amplification of the polymorphic bacterial internal transcribed spacer (ITS) from the plants’ organs DNA revealed a more diverse endophytic community, with more Gram+, among which a Rubrobacteridae that was never found associated with plants before. This work represents the first study of endophytes in Katangan cuprophytes. [ABSTRACT FROM AUTHOR]

Pollution by heavy metals is one of the strongest environmental constraints in human-altered environments that only a handful of species can cope with. Identifying the genes conferring to those species the ability to grow in polluted areas is a first step towards a global understanding of the evolutionary processes involved and will eventually improve phytoremediation practices. We used a genome-scan approach to detect loci under divergent selection among four populations of Arabidopsis halleri growing on either polluted or nonpolluted habitats. Based on a high density of amplified fragment length polymorphism (AFLP) markers (820 AFLP markers, i.e. ~1 marker per 0.3 Mb), evidence for selection was found for some markers in every sampled population. Four loci departed from neutrality in both metallicolous populations and thus constitute high-quality candidates for general adaptation to pollution. Interestingly, some candidates differed between the two metallicolous populations, suggesting the possibility that different loci may be involved in adaptation in the different metallicolous populations. [ABSTRACT FROM AUTHOR]