Unravelling mycorrhiza-induced wheat susceptibility to the English grain aphid Sitobion avenae

Amma L Simon,Gudbjorg I Aradottir,Alan C Gange,Peter A D Wellham

doi:10.1038/srep46497

Amma L Simon, Gudbjorg I Aradottir + Show 2 more

Open Access

https://doi.org/10.1038/srep46497

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Abstract

Arbuscular mycorrhizal (AM) fungi are root symbionts that can increase or decrease aphid growth rates and reproduction, but the reason by which this happens is unknown. To investigate the underlying mechanisms of this interaction, we examined the effect of AM fungi on the English Grain aphid (Sitobion avenae) development, reproduction, attraction, settlement and feeding behaviour on two naturally susceptible varieties Triticum aestivum (L.) variety Solstice and T. monococcum MDR037, and two naturally resistant lines, T. monococcum MDR045 and MDR049. Mycorrhizal colonisation increased the attractiveness of T. aestivum var. Solstice to aphids, but there was no effect on aphid development on this variety. Using the Electrical Penetration Graph (EPG) technique, we found that mycorrhizal colonisation increased aphid phloem feeding on T. monococcum MDR037 and MDR045, colonisation also increased growth rate and reproductive success of S. avenae on these varieties. Mycorrhizas increased vascular bundle size, demonstrating that these fungi can influence plant anatomy. We discuss if and how this could be related to an enhanced success rate in phloem feeding in two varieties. Overall, we present and discuss how mycorrhizal fungi can affect the feeding behaviour of S. avenae in wheat, inducing susceptibility in a resistant variety.

Highlights

The main measure used to control pest populations are insecticides, ; S. avenae populations have developed resistance to classes of pesticides rendering them ineffective[13], resulting in widespread infestation[18] and focusing efforts on finding alternative control methods
This study investigated if resistance in T. monococcum varieties was due to antixenosis and/or antibiosis and if this resistance can be affected by Arbuscular mycorrhizal (AM) fungi
We investigated four hypotheses: 1) AM fungi increase the development and fecundity of S. avenae, 2) mycorrhizal colonisation increases the attractiveness of T. aestivum var

Summary

Introduction

The main measure used to control pest populations are insecticides, ; S. avenae populations have developed resistance to classes of pesticides rendering them ineffective[13], resulting in widespread infestation[18] and focusing efforts on finding alternative control methods. We determined whether mycorrhizal colonisation can affect the resistance and susceptibility that diploid T. monococcum varieties, and T. aestivum, hold towards S. avenae, through fecundity and development studies using whole plant cages. Solstice and T. monococcum varieties resulting in more aphids settling on treated plants, 3) that AM fungi influences vascular bundle size, and 4) AM fungi influence feeding behaviour, through increased sap ingestion.

Results

Conclusion