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Thesis started November, 15^th, 2016. Defended in May, 19th, 2020.
Fund:  CIFRE
Direction: Eric Grenier, Josselin Montarry, Sylvain Fournet

Abstract: Cyst nematodes are among the most harmful pests of cultivated crops causing important economic losses. For cyst nematodes, the hatching is stimulated by root exudates released by the host plant. The removal of chemical nematicides requires development of alternative approaches to protect crops. For this purpose, root exudates may constitute an effective and innovative biocontrol method that could be used in the absence of the host plant to induce a “suicide hatching” of nematode and to control cyst nematodes’ pressure on crop. This work aimed to anticipate the effectiveness of the suicide hatching strategy, taking into account the influence of the genetic diversity of nematode populations and the microbial composition of soils. First, the level of dependence between root exudates from wild Solanum species and Globodera pallida populations for the hatching trait was evaluated and highlighted a strong effect of the geographical location of root exudates. Second,  root exudates from different plant species were tested on the hatching of representative populations of the genetic diversity for three cyst nematodes. Significant differences were obtained among populations for a given nematode species but root exudates provided a high level of hatching of nematodes. Third, the impact of microbial communities of soil on the  efficiency of root exudates to stimulate the hatching was measured. Significant differences of suicide hatching between different soils were obtained but the hatching rate remained high. These research efforts provide key elements for the development of root exudates as new biocontrol strategy.

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