Mycorrhizal fungi compromise production of endophytic alkaloids, increasing plant susceptibility to an aphid herbivore

Symbiosis plays a critical role in plant biology. Temperate grasses often associate with several symbiotic fungi simultaneously, including Epichloë endophytes and arbuscular mycorrhizal (AM) fungi, in shoots and roots, respectively. These symbionts often modulate plant-herbivore interactions by influencing nutritional traits (i.e., AM fungi-mediated nutrient uptake) and/or the secondary chemistry (i.e., endophytic alkaloids) of their host plant. Moreover, such grasses also accumulate large amounts of silicon (Si) from the soil, which can be deposited in tissues to act as a physical antiherbivore defense.
Recent evidence suggests that both endophytes and AM fungi independently facilitate Si uptake. However, the consequences of their interactions for piercing-sucking insects (i.e., aphids), or whether Si supply, endophytes and AM fungi interact in this regard, are currently unknown. While Si deposition may be less effective against aphids than other herbivores (i.e., chewing caterpillars)...,
Plants, Insects and Experimental procedure

Two hundred tall fescue plants (Festuca arundinacea cv. INIA Fortuna) either Epichloë-free (Nil; N = 100) or infected with the animal safe AR584 novel Epichloë coenophiala (formerly Neotyphodium coenophiala) strain (N = 100) were grown individually from seed in one-litre pots. Initially, these seeds were inoculated with the AR584 endophyte strain by AgResearch NZ, in collaboration with INIA under a work cooperation agreement. Following the endophyte incorporations, two distinct seed lines were maintained at the Margot Forde Forage Germplasm Centre (Palmerston North, NZ). Pots contained gamma-irradiated (50 kGy) 1:1 topsoil-sand mix that was homogenised with a soil mixer. Sand was used to reduce bioavailable phosphorus to <16 mg P kg-1 and silicon to < 11 mg Si kg-1 (Table S1 Appendix S1).
The top ¼ of each pot received one of two AM fungi treatments: No AM (-AM) or Commercial AM (+AM). +AM was achieved by inoculating soil with Start-up..., , # Data from: Mycorrhizal fungi compromise production of endophytic alkaloids, increasing plant susceptibility to an aphid herbivore

[https://doi.org/10.5061/dryad.6m905qg8c](https://doi.org/10.5061/dryad.6m905qg8c)

## Description of the data and file structure

In a factorial greenhouse experiment we evaluated whether these components, acting alone or in combination, altered 1) foliar primary chemistry (PYTO cvs), 2) Si and symbiont-chemical (endophytic alkaloids) defenses(POP cvs), as well as 3) performance of the bird-cherry oat aphid (*Rhopalosiphum padi*) feeding on tall fescue (*Festuca arundinacea*) (IND cvs).

### Files and variables

#### File: IND.csv

**Description:** 

##### Variables

* BLOCK: BLOCK DESIGN
* PL: PLANT NUMBER
* VAR: VARIETY
* AMF: WITH OR WITHOUT AMF
* Si: WITH OR WITHOUT Si supply
* CAGE : TYPE OF CAGE
* C#: CAGE NUMBER
* DTA: DAYS TO ADULT
* DaA: DAYS TO ADULT
* Tfec(7): TOTAL FECUNDITY
* Fec.d: DAILY FECUNDITY
* lnfec: ENDO COLONIZATION
* long: LONGEVITY...