Wallander H, Nylund JE, Sundberg B
The Influence of Iaa, Carbohydrate and Mineral Concentration in Host Tissue on Ectomycorrhizal Development on Pinus-Sylvestris L in Relation to Nutrient Supply
New Phytologist: 1994 127:521-528
Concentrations of indole-3-acetic acid (IAA) in lateral roots, fungal biomass (ergosterol) in lateral roots and extramatrical mycelium, and carbohydrates and minerals in shoots were measured in mycorrhizal and nonmycorrhizal Pinus sylvestris L. seedlings supplied with different amounts of N and P. IAA concentrations in lateral roots of mycorrhizal seedlings were the same or lower than those in control seedlings. The concentrations of IAA in mycorrhizal root tips of Laccaria bicolor-inoculated seedlings were 40% lower than those in lateral roots. IAA concentrations in lateral roots of L. bicolor-inoculated seedlings were positively related to N supply. A rise in N supply reduced the development of extramatrical mycelium of L. bicolor and the fungal biomass in lateral roots of Hebeloma crustuliniforme-inoculated seedlings. High N supply reduced concentrations of starch, Ca and Mg in shoots but increased those of glucose and fructose. P had no effect on fungal growth or on concentrations of IAA. Fungal growth was negatively correlated with levels of soluble carbohydrates in shoots, shoot concentrations of N, P and K, relative growth rate and the shoot:root ratio of the seedlings. Starch, Mg and Ca concentrations in the shoot were positively correlated with fungal growth. No support was found for the hypothesis that IAA is important in regulating mycorrhizal colonization.
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