Variation in mycorrhizal growth response among a spring wheat mapping population shows potential to breed for symbiotic benefit

Abstract

All cereal crops engage in arbuscular mycorrhizal symbioses which can have profound, but sometimes deleterious, effects on plant nutrient acquisition and growth. The mechanisms underlying variable mycorrhizal responsiveness in cereals are not well characterised or understood. Adapting crops to realise mycorrhizal benefits could reduce fertiliser requirements and improve crop nutrition where fertiliser is unavailable. We conducted a phenotype screen in wheat (Triticum aestivum L.), using 99 lines of an Avalon × Cadenza doubled‐haploid mapping population. Plants were grown with or without a mixed inoculum containing 5 species of arbuscular mycorrhizal fungi. Plant growth, nutrition and mycorrhizal colonisation were quantified. Plant growth response to inoculation was remarkably varied among lines, ranging from more than 30% decrease to 80% increase in shoot biomass. Mycorrhizal plants did not suffer decreasing shoot phosphorus concentration with increasing biomass as observed in their non‐mycorrhizal counterparts. The extent to which mycorrhizal inoculation was beneficial for individual lines was negatively correlated with shoot biomass in the non‐mycorrhizal state but was not correlated with the extent of mycorrhizal colonisation of roots. Highly variable mycorrhizal responsiveness among closely related wheat lines and the identification of several QTL for these traits suggests the potential to breed for improved crop‐mycorrhizal symbiosis.

Impacts of aphid herbivory on mycorrhizal growth responses across three cultivars of wheat

“…Avalon and cv. Cadenza, represent parental lines of the UK bread wheat reference population (Ma et al, 2015), with known differences in canopy traits (Piñera-Chavez et al, 2021), resistance to biotic stressors (Bass et al, 2006;Gardiner et al, 2020) and function of mutualists (Thirkell et al, 2019(Thirkell et al, , 2022. The third, cv.…”

Carbohydrate and lipid balances in the positive plant phenotypic response to arbuscular mycorrhiza: increase in sink strength

“…Different degrees of colonization and plant growth responses, from positive to negative, have been previously described in mycorrhizal interactions. This spectrum of responses can be influenced by various factors, including the type of AM fungi and the species or variety of the host plant (Janos, 2007; Thirkell et al, 2022; Tran et al, 2019). The plant's phenotypic outcomes depend on the balance of benefits and costs of the plant‐microbial interaction, which can be shaped by extrinsic conditions, including the availability of P (Smith et al, 2011).…”

“…interactions. This spectrum of responses can be influenced by various factors, including the type of AM fungi and the species or variety of the host plant (Janos, 2007;Thirkell et al, 2022;Tran et al, 2019).…”

Track and trace: how soil labelling techniques have revealed the secrets of resource transport in the arbuscular mycorrhizal symbiosis

“…The predicted increase in atmospheric CO 2 concentrations may confer a 'fertilisation effect' on many species of plants, including some important crop species (Müller et al 2014). There are concerns, however, about a counter-productive 'dilution effect' of nutrients in plant tissues because of increased plant biomass without a proportional increase in nutrient uptake, and whether that could be mitigated by AM fungal contributions to nutrient acquisition (He and Nara 2007;Thirkell et al 2022). It has been hypothesised that AM fungi will drive the nature of the fertilisation effect due to interactions with N availability (Terrer et al 2016) and P availability (Treseder 2004).…”