Ecto- and arbuscular mycorrhizal symbiosis can induce tolerance to toxic pulses of phosphorus in jarrah (Eucalyptus marginata) seedlings

Abstract

In common with many plants native to low P soils, jarrah (Eucalyptus marginata) develops toxicity symptoms upon exposure to elevated phosphorus (P). Jarrah plants can establish arbuscular mycorrhizal (AM) and ectomycorrhizal (ECM) associations, along with a non-colonizing symbiosis described recently. AM colonization is known to influence the pattern of expression of genes required for P uptake of host plants and our aim was to investigate this phenomenon in relation to P sensitivity. Therefore, we examined the effect on hosts of the presence of AM and ECM fungi in combination with toxic pulses of P and assessed possible correlations between the induced tolerance and the shoot P concentration. The P transport dynamics of AM (Rhizophagus irregularis and Scutellospora calospora), ECM (Scleroderma sp.), non-colonizing symbiosis (Austroboletus occidentalis), dual mycorrhizal (R. irregularis and Scleroderma sp.), and non-mycorrhizal (NM) seedlings were monitored following two pulses of P. The ECM and A. occidentalis associations significantly enhanced the shoot P content of jarrah plants growing under P-deficient conditions. In addition, S. calospora, A. occidentalis, and Scleroderma sp. all stimulated plant growth significantly. All inoculated plants had significantly lower phytotoxicity symptoms compared to NM controls 7 days after addition of an elevated P dose (30 mg P kg−1 soil). Following exposure to toxicity-inducing levels of P, the shoot P concentration was significantly lower in R. irregularis-inoculated and dually inoculated plants compared to NM controls. Although all inoculated plants had reduced toxicity symptoms and there was a positive linear relationship between rank and shoot P concentration, the protective effect was not necessarily explained by the type of fungal association or the extent of mycorrhizal colonization.

Trade-Offs in Arbuscular Mycorrhizal Symbiosis: Disease Resistance, Growth Responses and Perspectives for Crop Breeding

“…AM symbiosis has been shown to reduce assimilation of other adverse heavy metals, such as copper, chromium, cadmium and cobalt [19,36,77]. It has been suggested that altered phosphate transport during AM colonization alleviates symptoms of phosphate toxicity in highly-fertilized soils [76]. AMF have also been suggested to reduce host sulphur starvation responses via AM-transport of sulphur-containing compounds [74,75].…”

“…AMF may also have potential for phytoremediation [36][37][38]; however, this review focusses on approaches that could be taken by crop breeding rather that adding AMF to soil. [4,[60][61][62][63][64][65][66] Water acquisition [67,68] Zinc acquisition [5,6] Drought tolerance [67,68] Salinity tolerance [29,[69][70][71] Reduced arsenic toxicity [72,73] Reduced sulphur starvation [74,75] Reduced phosphate toxicity [76] Reduced assimilation of adverse heavy metals [19,36,77] Disease resistance Increased resistance to root [31,[78][79][80] and foliar [81][82][83][84][85] pathogens Reduced arbuscular mycorrhizal colonization in mlo mutants [86] Jasmonic acid production [87][88][89][90] Components required for AM colonization used by pathogens, Golovinomyces cichoracerum (DC.) V.P.…”

Effect of plant root symbionts on performance of native woody species in competition with an invasive grass in multispecies microcosms

“…This AMF species has been found in old‐fields elsewhere including those at Cedar Creek USA (Johnson, Zak, Tilman, & Pfleger, ). Scutellospora calospora can form associations with jarrah (Eucalyptus marginata) seedlings (Kariman, Barker, Finnegan, & Tibbett, ), and we expected it would form associations with the four myrtaceous species and two Acacia species planted in our experiment. Rhizobia tend to be generalists in their associations with legumes (incl.…”

Influence of season and edaphic factors on endorhizal fungal associations in subtropical plantation forest trees of Northeastern India

“…The cooccurrence of AMF and EcM fungi in the same root system shows that the capability to form AM has been maintained to some degree in plant taxa which are typically EcM (Moyersoen and Fitter, 1999). However, the role of AMF in such tree species has been a matter of controversy during the past decades due to inconsistent results (Kariman et al, 2014). Studies have shown positive effects of AMF on the growth of tree species that have the potential to form ectomycorrhizae under P deficient conditions (Adjoud et al, 1996;Chen et al, 2000;Kariman et al, 2014), and a succession of these mycorrhizal types has been reported during different stages of plant growth (Santos et al, 2001).…”

“…However, the role of AMF in such tree species has been a matter of controversy during the past decades due to inconsistent results (Kariman et al, 2014). Studies have shown positive effects of AMF on the growth of tree species that have the potential to form ectomycorrhizae under P deficient conditions (Adjoud et al, 1996;Chen et al, 2000;Kariman et al, 2014), and a succession of these mycorrhizal types has been reported during different stages of plant growth (Santos et al, 2001). Investigations on the influence of DSE fungi on plant growth further indicate that inoculation with these fungi can increase biomass as well as nutrient content of plants (see Newsham, 2011 and references therein).…”