Hatching of Globodera pallida Induced by Root Exudates Is Not Influenced by Soil Microbiota Composition

Abstract

Plant-parasitic nematodes are among the most harmful pests of cultivated crops causing important economic losses. The ban of chemical nematicides requires the development of alternative agroecological approaches to protect crops against nematodes. For cyst nematodes, egg hatching is stimulated by host plant root exudates. Inducing “suicide hatching” of nematode second-stage juveniles (J2), using root exudates in the absence of the host plant, may constitute an effective and innovative biocontrol method to control cyst nematodes. However, before considering the development of this approach, understanding the effect of soil biotic component on cyst nematode hatching by root exudates is a major issue. The effectiveness of this approach could be modulated by other soil organisms consuming root exudates for growth as soil microbiota, and this must be evaluated. To do that, four different native agricultural soils were selected based on their physicochemical properties and their microbiota composition were characterized by rDNA metabarcoding. To disentangle the effect of microbiota from that of soil on hatching, four recolonized artificial soils were obtained by inoculating a common sterile soil matrix with the microbiota proceeding from each agricultural soil. Each soil was then inoculated with cysts of the potato cyst nematode, Globodera pallida , and low or high doses of potato root exudates (PREs) were applied. After 40 days, viable J2 remaining in cysts were counted to determine the efficiency of root exudates to stimulate hatching in different soils. Results showed that (i) when physicochemical and microbiota compositions varied among native soils, the hatching rates remained very high albeit small differences were measured and no dose effect was detected and (ii) when only microbiota composition varied among recolonized soils, the hatching rates were also high at the highest dose of PREs, but a strong dose effect was highlighted. This study shows that abiotic and biotic factors may not compromise the development of methods based on suicide hatching of cyst nematodes, using root exudates, molecules inducing J2 hatch, or trap crops.

An Evaluation of Irradiation Treatment to Disinfect Soil Tare from Globodera spp.

“…Moreover, unlike with the use of chemical treatments, no toxic residues remain in the soils. The unwanted effects on soil structure, as observed in steamed or autoclaved soils, are completely missing and the dynamics of the loss or unavailability of major nutrients might not be affected; even high doses of γ irradiation at 35 kGy do not affect the physicochemical properties of the treated soils [43]. Our findings also reflect that the maize seedling growth in irradiated soils was similar to the growth in untreated soils.…”

Slight induction and strong inhibition of Heterodera glycines hatching by short-chain molecules released by different plant species

“…In recent years, studies have revealed VOCs emitted by plant residues with nematicidal activity similar to commercial nematicides (Gomes et al, 2020;. In the present study, several compounds identified in plant emissions, such as 3-methyl-1-butanol, 2-methyl-1-butanol, 3-pentanone, 2-nonanone, linalool, m-cymene, 2-octanol, 2-ethyl-1hexanol, ethyl acetate, 2-ethylfuran and 2-octanone JOURNAL OF NEMATOLOGY have proven nema ticidal activity (Aissani et al, 2015;Gu et al, 2007;Hewavitharana et al, 2014;Sharma et al, 2018;Zhai et al, 2018).…”

“…VOCs were extracted via headspace solid phase microextraction (SPME) (Arthur and Pawliszyn, 1990). The parameters for SPME and gas chromatography-mass spectrometry (GC-MS) were identical to those described in previous work by Gomes et al (2020).…”

“…Although studies on the effects of VOCs on hatching are scarce, the nematicidal activity of these molecules have received more attention (Aissani et al, 2015;Barros et al, 2014;Silva et al, , 2019. In addition, many of them have the potential to be used as soil biofumigants (Gomes et al, 2020;Ntalli et al, 2018;Pedroso et al, 2019).…”

Dynamic changes of soil microorganisms in rotation farmland at the western foot of the Greater Khingan range

“…Wheat-root associated microbial community assembly was shaped predominantly by different factors while within each factor, location had stronger effects on the variation in prokaryotic community than growth stage or variety. Similarly, crops affect the soil microbial community and nutrients in the farmland ecosystem (Gautier et al, 2020). Simultaneously, microbial substrate decomposition, energy transfer, and nutrient cycling adversely affect crop development (Stefan et al, 2021;Xie et al, 2022).…”