Genetic Variability in Balkan Paleoendemic Resurrection Plants Ramonda serbica and R. nathaliae Across Their Range and in the Zone of Sympatry.

The genus Ramonda includes three Paleoendemic and Tertiary relict species that survived in refugial habitats of the Balkan Peninsula (R. nathaliae and R. serbica) and the Iberian Peninsula (R. myconi). They are all "resurrection plants," a rare phenomenon among flowering plants in Europe. Ramonda myconi and R. nathaliae are diploids (2n = 2x = 48), while R. serbica is a hexaploid (2n = 6x = 144). The two Balkan species occur in sympatry in only two localities in eastern Serbia, where tetraploid potential hybrids (2n = 4x = 96) were found. This observation raised questions about the existence of gene flow between the two species and, more generally, about the evolutionary processes shaping their genetic diversity. To address this question, genetic markers (AFLP) and an estimate of genome size variation were used in a much larger sample and at a larger geographic scale than previously. The combination of AFLP markers and genome size results suggested ongoing processes of interspecific and interploidy hybridization in the two sites of sympatry. The data also showed that interspecific gene flow was strictly confined to sympatry. Elsewhere, both Ramonda species were characterized by low genetic diversity within populations and high population differentiation. This is consistent with the fact that the two species are highly fragmented into small and isolated populations, likely a consequence of their postglacial history. Within sympatry, enormous variability in cytotypes was observed, exceeding most reported cases of mixed ploidy in complex plant species (from 2x to >8x). The AFLP profiles of non-canonical ploidy levels indicated a diversity of origin pathways and that backcrosses probably occur between tetraploid interspecific hybrids and parental species. The question arises whether this diversity of cytotypes corresponds to a transient situation. If not, the question arises as to the genetic and ecological mechanisms that allow this diversity to be maintained over time.

Strategies of accumulation of potentially toxic elements in Minuartia recurva and M. bulgarica.

The aim of this study was to determine the concentrations of potentially toxic elements in soil samples and plant tissues of Minuartia recurva and M. bulgarica, predominantly or exclusively calcifuge species. Biological concentration (BCs) and translocation factors (TFs) were used to evaluate their accumulation potential. Considerable differences were observed between M. recurva and M. bulgarica assessions in terms of accumulation strategies of potentially toxic elements (PTEs). In M. recurva, most of the elements analyzed (Mn, Cu, Zn, Cd, and Co) were transported to the shoot, whereas in M. bulgarica, these elements remained predominantly in the roots. The Cu concentrations in the shoot samples of M. recurva from an abandoned iron-copper mine at Mt. Kopaonik were clearly above the notional hyperaccumulation threshold, characterizing this species as a possible Cu hyperaccumulator. Additionally, strong accumulation potential for Cr, Ni, Zn, Pb, and Cd was observed in M. recurva assessions, but without significant accumulation due to the low concentrations of these elements in the soils. The strong accumulation capacity and the different strategies in tolerance to PTEs indicate a potential of the two species for an application in phytoremediation: M. recurva for phytoextraction and M. bulgarica for phytostabilization.

Plantago subulata as indicator of potentially toxic elements in the substrate.

Plantago subulata is a facultative serpentinophyte, with predominantly ultramafic distribution in Serbia and Montenegro. The plant samples were collected from ultramafic and non-ultramafic substrate, including two abandoned mining sites, with the aim to assess the accumulation potential of this species. The samples were collected from 10 sites in Serbia and Montenegro and element concentrations in plants and soils were determined. Particularly high concentrations of Fe, Cu, Mn, Zn, and Cd were found in the soil and plant samples from an abandoned iron mining site, Mt. Kopaonik, Suvo Rudiste. The concentrations of Ni, Cr, Fe, Co, and Cd were statistically different between soil and plant samples from ultramafic and non-ultramafic bedrock. Considering the fact that concentrations of Zn, Ni, and Cr in roots and shoots were positively correlated with their respective contents in the soil, i.e., the chemical composition of the plant and soil samples reflected the characteristics of the substrate, and for most of the elements analyzed, P. subulata acted as indicator species. For Cd and Pb, only the root concentrations were positively correlated with soil content, indicating exclusion and root sequestration as the main tolerance strategies for these elements. Although below the hyperaccumulation threshold, a strong accumulation capacity of P. subulata was found for Ni and Cu.

Assessment of trace element accumulation potential of Noccaea kovatsii from ultramafics of Bosnia and Herzegovina and Serbia.

In this work, we present the results of the investigation of trace elements (Fe, Mg, Ni, Zn, Cu, Cr, Co, Cd, Pb) accumulation potential of Noccaea kovatsii (Heuff.) F. K. Mey., from the Balkan Peninsula. The study included eight populations from ultramafic soils, six from Bosnia and Herzegovina, and two from Serbia. Principal component analysis (PCA) was used to reveal relationships of elements in soil, and Pearson's correlation coefficients for analysing associations of available quantities of elements in soil and those in roots and shoots of N. kovatsii. Uptake and translocation efficiency was assessed by using bioconcentration (BCF) and translocation factors (TF). All the analysed populations of N. kovatsii emerged as strong Ni accumulators, with the highest shoot concentrations of 12,505 mg kg-1. Even thought contents of Zn in plant tissues of N. kovatsii were under the hyperaccumulation level (602 mg kg-1 and 1120 mg kg-1 respectively), BCF was up to 667, indicating that certain surveyed populations have strong accumulative potential for this element.

Micro-edaphic factors affect intra-specific variations in trace element profiles of Noccaea praecox on ultramafic soils.

The aim of this study was to compare trace element profiles of Noccaea praecox (Wulfen) F. K. Mey. growing on ultramafic soils in different habitat types and to observe differences in uptake and translocation of trace elements. Physico-chemical characteristics of the soil and concentrations of P2O5, K2O, Ca, Fe, Mn, Zn, Cu, Ni, Cr, Pb, Cd, and Co in plant samples were presented. Biological concentration, accumulation, and translocation factors were calculated to estimate accumulation potential of different N. praecox accessions. All of the studied accessions were Ni hyperaccumulators (with shoot concentrations up to 14,593 mg kg-1), but with notable differences in accumulation and translocation rates. Significant differences in accumulation and translocation patterns of trace elements were observed among accessions from habitats characterized as serpentine steppes on dry, shallow soils in contrast to the accessions from habitats with higher soil moisture, and higher content of organic matter.

Strategies of heavy metal uptake by three Armeria species growing on different geological substrates in Serbia.

This study surveyed three species of the genus Armeria Willd. from five ultramafic outcrops, two non-ultramafic (schist) soils, and one tailing heap of an abandoned iron-copper mine from Serbia. Similarities and differences among the three Armeria species growing on different geological substrates in the ability to control uptake and translocate nine metals were examined. Chemical characteristics of the soil and plant samples (concentrations of P2O5, K2O, Ca, Fe, Mn, Ni, Zn, Cu, Cr, Co, Cd, and Pb) are presented. In order to assess accumulative potential of these three Armeria species, biological concentration, accumulation, as well as translocation factors were used. Three investigated Armeria species growing on eight different localities showed large differences in heavy metal uptake, translocation, and accumulation. The differences were present among the plant samples of the same species and even more among three different Armeria species and were primarily the result of the different contents of available heavy metals in the investigated soils. Additionally, differences might be the consequence of diverse responses and possible presence of supplementary resistance mechanisms in the plants from the ultramafic soils. None of the three Armeria species showed shoot hyperaccumulative potential for any of the investigated heavy metals and they could be considered as root accumulators, considering their potential to accumulate medium to large amounts of Zn (BCF up to 134), Cr (BCF up to 148), and Cd (BCF up to 9) in their roots.