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Changes in carbon allocation and expression of carbon transporter genes in Betula pendula Roth. colonized by the ectomycorrhizal fungus Paxillus involutus (Batsch) Fr
- Wright, D.P., Scholes, J.D., Read, D.J., Rolfe, S.A.
- Plant, cell and environment 2000 v.23 no.1 pp. 39-49
- nutrient content, ribosomal RNA, Paxillus involutus, phosphorus, roots, nitrogen content, cell walls, gene expression, hexoses, photosynthesis, plant nutrition, sucrose, translocation (plant physiology), amino acid sequences, Betula pendula, beta-fructofuranosidase, biomass production, dry matter partitioning, ectomycorrhizae, diurnal variation, nucleotide sequences
- Comparative analyses of aspects of the carbon physiology and the expression of C transporter genes in birch (Betula pendula Roth.) colonized by the ectomycorrhizal fungus Paxillus involutus (Batsch) Fr. were performed using mycorrhizal (M) and non-mycorrhizal (NM) plants of similar foliar nutrient status. After six months of growth, the biomass of M plants was significantly lower than that of NM plants. Diurnal C budgets of both sets of plants revealed that M plants exhibited higher rates of photosynthesis and root respiration expressed per unit dry weight. However, the diurnal net C gain of M and NM plants remained similar. Ectomycorrhizal roots contained higher soluble carbohydrate pools and increased activity of cell wall invertase, suggesting that additional C was allocated to these roots and their ectomycorrhizal fungi consistent with an increase sink demand for C due to the presence of the mycobiont. In M roots, the expression of two hexose and one sucrose transporter genes of birch were reduced to less than one-third of the expression level observed in NM roots. Analysis using a probe against the birch ribosomal internal transcribed spacer region revealed that M roots contained 22% less plant RNA than NM roots. As the expression of birch hexose and sucrose transporter genes was reduced to a much greater extent, this suggest that these specific genes were down-regulated in response to alterations in C metabolism within M roots.