Project 5

Tapping into signaling interactions between nematodes and aphids

Supervisors: Nicole M. van Dam, iDiv  & FSU, Dr Grit Kunert, MPI for Chemical Ecology

Background: In natural environments, plants are commonly infested by both aboveground and belowground pests. This causes interactions between shoot and root herbivores via systemic induced responses. This is the case for cabbage aphids (Brevicoryne brassicae) feeding on Brassica plants infested by root feeding nematodes. Aphid population growth increased on plants infested with root knot nematodes (Meloidogyne spp.), whereas it was lower on plants infested by root lesion nematodes (Pratylenchus penetrans) or cyst nematodes (Heterodera schachtii) (Hol et al., 2013, Hol et al., 2016). This was linked to hormonal signaling interfering with aphid-induced responses (van Dam et al., 2018). However, the exact mechanisms or the nature and intensity of phloem-based signals, e.g. phytohormones, miRNA or Ca²+-ions, are as yet unknown. Moreover, not only the type of nematode but also the infestation stage of the nematode may alter the aphid performance (Mblaluto, van Dam, Martinez-Medina, unpublished). Whether nematode infestation also affects higher trophic levels (parasitoids, predators) via changes in aphid quality or plant volatile emissions is also unknown so far.

Project Description: The aim of this project is to identify the molecular and chemical mechanisms underlying changes in aphid preference and performance on nematode infested plants. Our hypotheses are:

  1. Nematode feeding on the roots changes phloem chemistry. These systemically induced changes affect the preference, feeding behavior, and performance of phloem feeding aphids as well as of their natural enemies.
  2. The interaction between nematodes and aphids causes specific defense signaling interactions in the shoot. The nature of the interaction depends on the feeding style of the nematode species.

We propose to use Brassica nigra and its specialist aphid Brevicoryne brassicae as core model system. For this project, iDiv and MPI-CE will provide their excellent chemical-molecular (mass spectrometry platforms, qPCR) and experimental facilities (greenhouses, growth rooms) as well as an EPG (electrical penetration graph technique) set-up. Collaborator:  Dr Alexandra Furch, FSU Jena (expert in phloem physiology and Ca2+ signaling). Primary working place will be in Leipzig (iDiv) with periods at MPI-CE in Jena to perform EPG analyses.

Candidate profile: We are looking for a highly motivated candidate with an MSc degree in Biology, Plant Sciences, Biochemistry or a related field. The candidate should have hands-on experience in molecular or chemical analyses, and preferably also with plant-aphid interactions. He or she should be able to work independently and be self-critical. Excellent English skills (written and spoken) are required.

Reading:

Hol WHG, Boer W, Termorshuizen AJ, Meyer KM, Schneider JHM, Putten WH, Dam NM (2013) Heterodera schachtii nematodes interfere with aphid-plant relations on Brassica oleracea. Journal of Chemical Ecology: 1193-1203.

Hol WHG, Raaijmakers CE, Mons I, Meyer KM, van Dam NM (2016) Root-lesion nematodes suppress cabbage aphid population development by reducing aphid daily reproduction. Frontiers in Plant Science 7

van Dam NM, Wondafrash M, Mathur V, Tytgat TOG (2018) Differences in hormonal signaling triggered by two root-feeding nematode species result in contrasting effects on aphid population Growth. Frontiers in Ecology and Evolution 6

Project 5 pdf