Does severe soil drought have after-effects on arbuscular and ectomycorrhizal root colonisation and plant nutrition?

Abstract

Background and aims Arbuscular (AM) and ectomycorrhizas (EM) predominate in different soils.We hypothesise that also climatic factors affect directly their relative success and AM fungi (AMF) generally tolerate drought better than EM fungi (EMF). Here we tested the colonisation rates of soil-borne AMF and EMF after soil drought treatments.Methods Forest and meadow soils were mixed to include AMF and EMF propagules. There were three soil treatments: soil moisture corresponding to 60% (control) or 10% in mass of maximum water retention, or air-dry. The bait plants were EM-forming silver birch (Betula pendula), dualmycorrhiza forming grey alder (Alnus incana) and AM-forming white clover (Trifolium repens).After re-watering, bait plants were sown and grown in a growth chamber in favourable conditions. This way, host-plant responses to drought were eliminated.Results Previous soil drought decreased EM colonisation in alder. The spore formation by AMF in clover was negatively affected after the most severe soil drought treatment, suggesting slightly retarded AM formation. Soluble soil potassium concentrations were lower in drought-treated soils and this was reflected in birch foliar concentrations. ConclusionsThe results provide some support to the hypothesised better drought tolerance of AMF than EMF propagules but further studies in milder drought and in other plant-fungus combinations are needed.

Dual‐mycorrhizal plants: their ecology and relevance

“…Soil drought is a very frequent environmental stressor for plants. In A. incana, drought significantly decreased EM colonization levels, while increasing the formation of arbuscules from AM fungi (Kilpelainen et al, 2017). Specificity of Alnus in forming EM symbioses may have partly confounded these results by limiting the number of EM fungal symbionts tolerant to drought stress.…”

“…Different letters indicate statistically significant differences (P < 0.05) according to Tukey honest significant difference tests. We used data from the following studies: McGee (1988), Lodge (1989), Watson et al (1990), Moyersoen & Fitter (1999) We propose the following mechanisms responsible for higher AM than EM colonization in very dry and very wet soils: (1) poor oxygen (O 2 ) availability in soil reduces EM dominance on roots since EM fungi do not develop properly in poorly aerated soil (Read & Armstrong, 1972); (2) EM fungi are more competitive and can displace AM fungi on roots when grown in well-drained (but not dry) soil; (3) AM fungal propagules have superior drought tolerance compared with EM fungal propagules, resulting in dual-mycorrhizal plants that are more AM dominated in dry soil (Kilpelainen et al, 2017); (4) AM fungi can increase the hydraulic conductivity of soil (Bitterlich et al, 2018); and (5) aquatic plants, which tend to be AM, can transport gases, including O 2 , within roots, and AM fungi may be capable of surviving by residing in cells of these roots. From the plant perspective, being able to form different types of mycorrhizas along moisture gradients may increase habitat breadth and resilience to flooding or drought.…”

Morphological and ecophysiological root and leaf traits in ectomycorrhizal, arbuscular-mycorrhizal and non-mycorrhizal Alnus incana seedlings

“…All other fungi used are considered generalists, able to colonise many host species. A soil mix from meadow and forest sites from eastern Finland was applied as inoculum too (Kilpeläinen et al 2016(Kilpeläinen et al , 2017. The soil and perlite were mixed in 3:7 vol.…”

Qualidade de mudas de espécies arbóreas procedentes do Bioma Pantanal e inoculadas com fungos micorrízicos

“…Sabe-se, até o presente momento, que a extensão da colonização micorrízica e seu efeito sob a espécie é variável, sendo condicionada pelo material genético utilizado (Dias et al, 2012), pela interação entre microssimbiontes (Santos et al, 2008) e pelo status nutricional do solo-substrato, especialmente do fósforo (Smith & Smith, 2012;Pedone-Bonfim et al, 2013). Fatores ambientais, como temperatura e umidade do solo, também são apontados por Lenoir et al (2016) e Kilpeläinen et al (2017), respectivamente, como importantes condicionantes da colonização micorrízica. Todavia, não há conhecimento sobre os efeitos destas variáveis nas duas espécies aqui avaliadas.…”