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Context and challenges

During their development cycle, plants maintain dynamic and intimate interactions with communities of microorganisms. Numerous studies illustrate the importance of these interactions on the growth, health and evolution of host organisms hosting these microorganisms.

An attack on a cultivated plant by a root pest insect involves an interaction between the two holobionts: the plant and the root and rhizosphere microbiotas on the one hand and the insect and its microbiota on the other. Although these two entities are usually thought to differ, in fact they have a common feature because by necessarily circumventing the plant’s defence molecules, the micro-organisms in the root and rhizosphere of the plant are also likely to be recruited by the pest in its intestinal microbiota, because of their detoxifying properties.

Goals

We are therefore proposing to determine the relative importance of the heritability and environmental origin of the microbiota of a root pest and to measure the impact of this recruitment on the adaptive value of the pest.

To achieve this work, massive sequencing of the dynamics of the insect microbiota (Delia radicum, or the cabbage root fly) throughout its life cycle will be carried out in parallel with monitoring of the dynamics of communities in the roots and rhizosphere of two rapeseed genotypes with contrasting contents in defence compounds. During a more functional, second part of the study, we shall quantify the defence compounds and hormones in the roots and the saxA bacterial gene known to degrade plant defence compounds, and produce metatranscriptomic data in order to better understand the nature of the interactions between the plant, microbiotas and insect.

INRAE Partners

Non INRAE partners