Population Genetics of Odontarrhena (Brassicaceae) from Albania: The Effects of Anthropic Habitat Disturbance, Soil, and Altitude on a Ni-Hyperaccumulator Plant Group from a Major Serpentine Hotspot.

Andrea Coppi,Federico Selvi,Cristina Gonnelli,Guillaume Echevarria,Isabella Bettarini,Luigia Pazzagli,Alan J M Baker,Ilaria Colzi

doi:10.3390/plants9121686

Andrea Coppi, Federico Selvi + Show 6 more

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https://doi.org/10.3390/plants9121686

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Abstract

Albanian taxa and populations of the genus Odontarrhena are most promising candidates for research on metal tolerance and Ni-agromining, but their genetic structure remains unknown. We investigated phylogenetic relationships and genetic differentiation in relation to distribution and ploidy of the taxa, anthropic site disturbance, elevation, soil type, and trace metals at each population site. After performing DNA sequencing of selected accessions, we applied DNA-fingerprinting to analyze the genetic structure of 32 populations from ultramafic and non-ultramafic outcrops across Albania. Low sequence divergence resulted in poorly resolved phylograms, but supported affinity between the two diploid serpentine endemics O. moravensis and O. rigida. Analysis of molecular variance (AMOVA) revealed significant population differentiation, but no isolation by distance. Among-population variation was higher in polyploids than in diploids, in which genetic distances were lower. Genetic admixing at population and individual level occurred especially in the polyploids O. chalcidica, O. decipiens, and O. smolikana. Admixing increased with site disturbance. Outlier loci were higher in serpentine populations but decreased along altitude with lower drought and heat stress. Genetic variability gained by gene flow and hybridization at contact zones with “resident” species of primary ultramafic habitats promoted expansion of the tetraploid O. chalcidica across anthropogenic sites.

Highlights

Nickel-accumulating plants are currently attracting considerable interest for both biotechnological applications and fundamental research on the genetic bases and molecular mechanisms of metal homeostasis, evolution, and adaptation to extreme environments [1,2,3]
The nuclear ribosomal DNA internal transcribed spacer region (ITS) alignment consisted of 629 bp, of which 479 conserved, 145 variable but phylogenetically non-informative and 99 (15.7%) informative; considering only the ingroup, only 50 positions (7.9%) were phylogenetically informative
The first is that the three accessions of typical O. muralis from outside Albania, including one from the type locality in Romania, are clustered in a separate clade, unlike all others from this country

Summary

Introduction

Nickel-accumulating plants are currently attracting considerable interest for both biotechnological applications and fundamental research on the genetic bases and molecular mechanisms of metal homeostasis, evolution, and adaptation to extreme environments [1,2,3]. Plants 2020, 9, 1686 constraints involved in metal accumulation ability [4], research in this field requires the use of appropriate model systems formed by closely related accumulating and non-accumulating taxa and/or species with populations from sites with high and low levels of Ni in the soil [5,6]. Odontarrhena; [7,8,9,10,11] The latter genus consists of nearly 90 species ranging from the Iberian peninsula to Iran and adjacent regions [12], of which about 60 are able to accumulate Ni well above 1000 μg g−1 dw

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