The impact of ectomycorrhiza formation on monosaccharide transporter gene expression in poplar roots

Abstract

Summary• By using degenerate primers, five putative poplar monosaccharide transporter genes were isolated from ectomycorrhizas by RT-PCR. The expression profiles of the three most strongly expressed ones are presented in detail.• Two transporter genes ( PttMST1.2 and PttMST2.2 ) were down-regulated by ectomycorrhiza formation. However, PttMST3.1 , which showed 10-times higher expression rates in noninfected roots than any other transporter gene, was upregulated 12-fold in mycorrhizas.• While changes in PttMST1.2 and PttMST2.2 expression might be regulated by a fungal metabolite present in axenically grown hyphae, the strong increase of PttMST3.1 expression in mycorrhizas required active plant-fungus interaction.• Up-regulation of PttMST3.1 by mycorrhiza formation suggests that root cells are able to compete with fungal hyphae for hexoses from the common apoplast during symbiosis, redirecting the sugar-flux back into plant cells whenever the fungal partner does not supply sufficient mineral nutrients. Such a mechanism would enable the plant to link nutrient supply and fungal carbon support at a local level.

Aquaporins in poplar: What a difference a symbiont makes!

“…Aliquots of about 1 lg were DNAse I treated and used for first-strand cDNA synthesis. The RNA concentration in the different samples was equalized according to the banding intensities obtained with 18S rRNA primers (data not shown) and the constitutively expressed poplar gene PttJip1 (Grunze et al 2004). PCRs were performed with gene specific primers from the non-coding 3¢-end of the genes development of dicotelydons (e.g.…”

“…For further PCR experiments, the amount of firststrand cDNA in the different samples was calibrated such, that all samples showed identical signal intensities after amplification with specific primers for the constitutively expressed poplar gene PttJip1 and 18S rRNA (Grunze et al 2004) followed by agarose gel electrophoresis and ethidium bromide staining. PCR was performed using 2 U Eurogentec Taq in a total volume of 25 ll containing 5% dimethyl sulfoxide (cycling conditions: 1 min at 91°C; 30 s at 55°C; 1.5 min at 72°C).…”

Sugar for my honey: Carbohydrate partitioning in ectomycorrhizal symbiosis

“…2). Always one Populus tremula · tremuloides member of each of the subgroups I, II and III was expressed in fine roots (Grunze et al, 2004). The spruce transporter PaMST1 that is also expressed in fine roots belongs to subgroup IV, in which no P. tremula · tremuloides homolog has been identified so far.…”

Effects of pH on NaCl tolerance of American elm (Ulmus americana) seedlings inoculated with Hebeloma crustuliniforme and Laccaria bicolor

“…Nevertheless, inoculation caused physiological responses in the seedlings, including leaf chlorosis, which was observed in the first few weeks after inoculation and was followed by full recovery after the seedlings were transplanted to larger pots prior to experimental treatments. It is not unusual for inoculation with ECM fungi to alter plant physiology and growth in the absence of well-developed mycorrhizas (KarabaghliDegron et al 1998;Grunze et al 2004;Rincon et al 2005). Such effects can be attributed to non-nutritional effects, such as production of auxins or other plant growth regulators (Karabaghli-Degron et al 1998) and can influence root development and plant water relations (Rincon et al 2005).…”