Effects of cadmium and mycorrhizal fungi on growth, fitness, and cadmium accumulation in flax (Linum usitatissimum; Linaceae).
OBJECTIVE
Agricultural soils have become contaminated with a variety of heavy metals, including cadmium. The degree to which soil contaminants affect plants may depend on symbiotic relationships between plant roots and soil microorganisms. We examined (1) whether mycorrhizal fungi counteract the potentially negative effects of cadmium on the growth and fitness of flax (Linum usitatissimum) and (2) whether mycorrhizal fungi affect the accumulation of cadmium within plant parts.


METHODS
Two flax cultivars (Linott and Omega) were grown in three soil cadmium environments (0, 5, and 15 ppm). Within each cadmium environment, plants were grown in either the presence or absence of mycorrhizal fungi. Upon senescence, we measured growth and fitness and quantified the concentration of cadmium within plants.


RESULTS
Soil cadmium significantly decreased plant fitness, but did not affect plant growth. Mycorrhizal fungi, which were able to colonize roots of plants growing in all cadmium levels, significantly increased plant growth and fitness. Although mycorrhizal fungi counteracted the negative effects of cadmium on fruit and seed production, they also enhanced the concentration of cadmium within roots, fruits, and seeds.


CONCLUSIONS
The degree to which soil cadmium affects plant fitness and the accumulation of cadmium within plants depended on the ability of plants to form symbiotic relationships with mycorrhizal fungi. The use of mycorrhizal fungi in contaminated agricultural soils may offset the negative effects of metals on the quantity of seeds produced, but exacerbate the accumulation of these metals in our food supply.
Department of Organismal and Environmental Biology, Christopher Newport University, 1 Avenue of the Arts, Newport News, Virginia 23606, USA.
Laura M S
LM
Hancock
Charlotte L
CL
Ernst
Rebecca
R
Charneskie
Lauren G
LG
Ruane
D000704:Analysis of Variance; D018533:Biomass; D002104:Cadmium / Q000378:metabolism* / Q000633:toxicity*; D015169:Colony Count, Microbial; D019597:Flax / Q000033:anatomy & histology / Q000187:drug effects / Q000254:growth & development* / Q000382:microbiology*; D005638:Fruit / Q000187:drug effects / Q000378:metabolism; D038821:Mycorrhizae / Q000187:drug effects*; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000378:metabolism; D018547:Plant Stems / Q000187:drug effects / Q000378:metabolism; D012639:Seeds / Q000187:drug effects / Q000378:metabolism; D012987:Soil / Q000737:chemistry
D012987:Soil; D002104:Cadmium