Variability of zinc tolerance among and within populations of the pseudometallophyte species Arabidopsis halleri and possible role of directional selection.
We estimated the level of quantitative polymorphism for zinc (Zn) tolerance in neighboring metallicolous and nonmetallicolous populations of Arabidopsis halleri and tested the hypothesis that divergent selection has shaped this polymorphism. A short-term hydroponic test was used to capture the quantitative polymorphism present between edaphic types, among and within populations. We measured six morphological and physiological traits on shoots and roots to estimate the response of A. halleri to Zn. In order to assess the adaptive value of Zn tolerance polymorphism, we compared differentiation of quantitative traits with that of molecular markers. Zinc tolerance of metallicolous populations was, on average, higher than that of nonmetallicolous populations according to the morphological and physiological traits measured. Phenotypic variability within edaphic types was very high and mainly explained by polymorphism among individuals within populations. Genetic differentiation for photosystem II yield of leaves (a measure of photosynthetic efficiency) was greater than the differentiation for microsatellite and thus, probably shaped by divergent selection. Overall, these results suggest that, in the sampled populations, Zn tolerance has been increased in metallicolous populations through selection on standing genetic variation within local nonmetallicolous ancestral populations.
Laboratoire de Génétique et Evolution des Populations Végétales, UMR CNRS 8016, Université des Sciences et Technologies de Lille, Bâtiment SN2, F-59655 Villeneuve d'Ascq Cedex, France. claire-lise.meyer@ed.univ-lille1.fr
Claire-Lise
CL
Meyer
Alicja A
AA
Kostecka
Pierre
P
Saumitou-Laprade
Anne
A
Créach
Vincent
V
Castric
Maxime
M
Pauwels
Hélène
H
Frérot
D000220:Adaptation, Biological; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D018895:Microsatellite Repeats; D010641:Phenotype; D010788:Photosynthesis / Q000235:genetics*; D045332:Photosystem II Protein Complex / Q000235:genetics; D018517:Plant Roots; D018520:Plant Shoots; D011110:Polymorphism, Genetic; D012641:Selection, Genetic; D015032:Zinc
D045332:Photosystem II Protein Complex; D015032:Zinc