Aluminum-mycorrhizal interactions in the physiology of pitch pine seedlings |
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Authors: | Jonathan R Cumming Leonard H Weinstein |
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Institution: | (1) Department of Natural Resources, Cornell University, 14853 Ithaca, NY, USA;(2) The Boyce Thompson Institute for Plant Research, Cornell University, 14853 Ithaca, NY, USA;(3) Present address: Department of Botany, University of Alberta, T6G 2E9 Edmonton, Alberta, Canada |
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Abstract: | Aluminum (Al) in the rhizosphere adversely affects plant nutrition and growth. Although many conifer species, and pitch pine
(Pinus rigida) in particular, have evolved on acidic soils where soluble Al is often high, controlled environment studies often indicate
that Al interferes with seedling growth and nutrient relations. Under normal field conditions, conifer roots grow in a symbiotic
relationship with ectomycorrhizal fungi, and this association may modulate the effects of Al on root physiology. To investigate
the influence of mycorrhizal infection on Al toxicity, pitch pine seedlings were grown with or without the ectomycorrhizal
symbiont Pisolithus tinctorius and were exposed to low levels of Al in sand culture. Aluminum at 50 μM reduced nonmycorrhizal seedling growth and increased foliar Al concentrations, but did not alter photosynthetic gas exchange
or other aspects of seedling nutrition. Nonmycorrhizal seedlings exposed to 200 μM Al exhibited decreased growth, increased transpiration rates, decreased water use efficiency, increased foliar Al and Na
levels, and reduced foliar P concentrations. Seedlings inoculated with P. tinctorius exhibited unaltered growth, physiological function, and ionic relations when exposed to Al. The fungal symbiont evidently
modulated ionic relations in the rhizosphere, reducing Al-P precipitation reactions, Al uptake, and subsequent root and shoot
tissue Al exposure. |
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Keywords: | aluminum ectomycorrhizae phosphorus Pinus rigida Pisolithus tinctorius sand culture |
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