Mycorrhizal symbiosis and phosphorus supply determine interactions among plants with contrasting nutrient‐acquisition strategies

Abstract

1. Highly diverse plant communities growing on nutrient-impoverished soils are test beds for theories on species coexistence. Here, neighbouring mycorrhizal and non-mycorrhizal plants compete for limited phosphorus. The impact of belowground interactions on community dynamics is underexplored.2. We used an experimental approach to investigate effects of inoculation with arbuscular mycorrhizal (AM) fungi and a phosphorus supply gradient on competitive and facilitative interactions among mixed assemblages of woody plants in microcosms. The plant species, one cluster root-forming (CR) species and four AM species, are native to jarrah forest that grows on nutrient-impoverished soils in south-western Australia. We measured plant growth in microcosms, with and without inoculation with the AM fungus Rhizophagus irregularis, and across a gradient of P supply: 0, 9, 27 and 243 mg P per kg of soil.3. Our data show evidence of plant-plant facilitation at low P supply and competition at high P supply. Growth of the CR species, Hakea undulata, was highest in microcosms with 0P and without AM inoculation. One AM species, Bossiaea aquifolium, also performed better at lower P levels, possibly benefitting from P mobilised by H. undulata. The other three AM species, one strongly obligates, performed better at higher P levels. Data for Acacia celastrifolia suggested it was facultatively mycotropic, and because there was no correlation between AM colonisation and the relative inoculum effect, we suggest positive effects of AM inoculation at 9P might be due to benefits other than P acquisition, such as pathogen defence.Benefit of AM inoculation diminished for three of four mycorrhizal species at the highest P level as we had predicted. The fourth species, Eucalyptus marginata (jarrah), had higher growth in microcosms that were not inoculated with AM, perhaps because the species benefits more from ectomycorrhizas.

Symbiotic Fungi Alter the Acquisition of Phosphorus in Camellia oleifera through Regulating Root Architecture, Plant Phosphate Transporter Gene Expressions and Soil Phosphatase Activities

“…The change in plant growth in PI- and DV-inoculated plants represented that the fungal colonization was associated with symbiotic fungi-improved growth responses [ 31 ]. In the present study, PI, FM, RI and mixed-AMF dramatically promoted plant growth parameters to varying degrees, which was consistent with the findings of Standish et al [ 32 ] in mango. However, the DV treatment in our study had no significant effect on plant growth performance, which may be related to the low colonization level of DV in roots.…”

Invasiveness, Monitoring and Control of Hakea sericea: A Systematic Review

“…The low N and P availability in Portuguese soils in invaded areas has led to an increase in Hakea proteoid root formation, with dense proteoid roots near the soil surface [ 101 ]. The low affinity of inorganic P transport is halved due to the high inorganic P availability, increasing P toxicity in response to increased P tissue concentration, due to an inability to downregulate P uptake, even in concentrations well below those observed for other species [ 93 , 101 , 109 , 110 ]. Shane et al and Shane et al described an increasing P toxicity with increasing Ca supply due to leaf P displacement into mesophyll cells [ 111 , 112 ], increasing tissue P concentrations [ 113 ].…”

“…In high-P-availability conditions, proteoid and mycorrhizal rooted plants compete for P acquisition. Inversely, in low-P environments there is a biotic relationship of P facilitation, where proteoid roots benefit from P immobilization by mycorrhizal roots [ 109 ]. As soil ages, the allocation of P to inorganic P, phospholipids, and nucleic acids decreases, while N remains constant.…”

Facilitative and competitive interactions between mycorrhizal and nonmycorrhizal plants in an extremely phosphorus‐impoverished environment: role of ectomycorrhizal fungi and native oomycete pathogens in shaping species coexistence

“…The ECM colonisation had negligible effects on the growth of E. todtiana , compared with what is commonly observed in environments with moderate P limitation or when plant growth is limited by other elements (Burgess et al ., 1993; Montesinos‐Navarro et al ., 2019). In severely P‐impoverished environments, ECM associations likely contribute other benefits to plants that are complementary to P nutrition, such as protection against root pathogens (Marx, 1972; Standish et al ., 2021). Teste et al .…”