The effect of ectomycorrhizae on water relations in aspen (Populus tremuloides) and white spruce (Picea glauca) at low soil temperatures

Abstract

Low soil temperatures, common during the growing season in northern forests, have the potential to impede plant growth. In this study, water uptake, water relations, and growth characteristics were examined in aspen (Populus tremuloides) and white spruce (Picea glauca) seedlings that were inoculated with ectomycorrhizal fungi and grown at 20°C daytime air temperatures and low soil temperatures of 4°C and 8°C. Mycorrhizal associations had little effect on root and shoot biomass at both soil temperatures. Root hydraulic conductance (Kr) was higher in both mycorrhizal plant species compared to nonmycorrhizal plants, but there was no soil temperature effect on Kr in either species. Mycorrhizae also increased shoot water potential (Ψw) in Populus tremuloides but had no effect on Ψw in Picea glauca. The increases in Kr and Ψw were not reflected by changes in stomatal conductance (gs) and transpiration rates (E), suggesting that the reduction of water flow in seedlings exposed to low soil temperature was not likely the factor limiting gs in both plant species.Key words: boreal forest, root hydraulic conductance, root growth, stomatal conductance, water uptake.

Aquaporins in poplar: What a difference a symbiont makes!

“…Similarly to previous reports with white spruce and Ulmus Landha¨usser et al 2002), an increased root hydraulic conductance of mycorrhized poplar plants, reflecting an increased water transport capacity of the root system in symbiosis, was observed in this contribution. However, as in white spruce and Ulmus, the larger activation energy for root water transport (E a ) of mycorrhized Table 1 Relative expression rates of PttPIP genes in poplar organs of non-mycorrhized (leaf, stem, main and fine root) and mycorrhized (main and fine root = mycorrhiza) plants obtained by semi-quantitative RT-PCR (Fig.…”

Fungal aquaporins: cellular functions and ecophysiological perspectives

“…MIPs have been discussed to be most important for this process, since the expression levels of certain fungal (Dietz et al 2011;Hacquard et al 2013;Xu et al 2013) and plant (Marjanovic et al 2005a, b) MIP members with proven water transportation capability is strongly increased upon symbiosis. In agreement with elevated AQP-mediated water permeability of fungal and plant plasma membranes in ECM symbiosis, hydraulic conductivity of roots is frequently increased in mycorrhized plants (Muhsin and Zwiazek 2002a;Muhsin and Zwiazek 2002b;Landhäusser et al 2002;Marjanovic et al 2005b; for a comprehensive review, see Lehto and Zwiazek 2011). However, a final proof of this concept of elevated water transfer between plant and fungal partners in ECM symbiosis by AQP-mediated increased cellular water permeability, e.g., by overexpression or suppression of selected fungal/plant AQPs, is still missing.…”

Ectomycorrhizal fungus (Paxillus involutus) and hydrogels affect performance of Populus euphratica exposed to drought stress

“…Mycorrhizal fungi can improve the water status of plants and increase plant survival and growth under drought conditions (Auge, 2001;Smith and Read, 1997), but the mechanisms of this protection are not clear (Marjanovic et al, 2005;Rincon et al, 2005). For example, in Populus tremuloides seedlings inoculated with ectomycorrhizal fungi, root hydraulic conductance and shoot water potential were higher than in non-mycorrhizal plants (Landhausser et al, 2002). It is generally believed that positive effects of mycorrhizal fungi on host plants are dependent on the formation of mycorrhizas, although there is evidence that mycorrhizal fungi affect host growth and metabolism even if no mycorrhizas are found in inoculated plants (e.g., Dell et al, 1994;Vierheilig et al, 1994).…”