Gautier Camille, Martinez Lisa, Fournet Sylvain, Montarry Josselin, Yvin Jean-Claude, Nguema-Ona Eric, Guillerm-Erckelboudt Anne-Yvonne, Piriou Christophe, Linglin Juliette, Mougel Christophe, Lebreton Lionel
Institut national de recherche pour l'agriculture, l'alimentation et l'environnement (INRAE), UMR1349 IGEPP, Institute of Genetic Environment and Plant Protection, Le Rheu, France.
Centre Mondial de l'Innovation-Roullier, Laboratoire de Nutrition Végétale - Pôle Stress Biotique, Saint Malo, France.
Front Microbiol. 2020 Oct 8;11:536932. doi: 10.3389/fmicb.2020.536932. eCollection 2020.
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, , 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.
植物寄生线虫是栽培作物中危害最大的害虫之一，会造成重大经济损失。化学杀线虫剂的禁用要求开发替代性农业生态方法来保护作物免受线虫侵害。对于孢囊线虫而言，寄主植物根系分泌物会刺激虫卵孵化。在没有寄主植物的情况下，利用根系分泌物诱导线虫二龄幼虫（J2）“自杀性孵化”，可能构成一种有效且创新的生物防治方法来控制孢囊线虫。然而，在考虑开发这种方法之前，了解土壤生物成分对根系分泌物诱导孢囊线虫孵化的影响是一个主要问题。这种方法的有效性可能会受到其他消耗根系分泌物以供生长的土壤生物（如土壤微生物群）的调节，对此必须进行评估。为此，根据四种不同原生农业土壤的理化性质进行选择，并通过rDNA宏条形码技术对其微生物群组成进行表征。为了区分微生物群和土壤对孵化的影响，通过用来自每种农业土壤的微生物群接种一种常见的无菌土壤基质，获得了四种重新定殖的人工土壤。然后向每种土壤接种马铃薯孢囊线虫的孢囊，并施加低剂量或高剂量的马铃薯根系分泌物（PREs）。40天后，对孢囊中存活的J2进行计数，以确定根系分泌物在不同土壤中刺激孵化的效率。结果表明：（i）当原生土壤的理化和微生物群组成不同时，尽管测量到的差异很小且未检测到剂量效应，但孵化率仍然很高；（ii）当重新定殖的土壤中仅微生物群组成不同时，在最高剂量的PREs下孵化率也很高，但突出显示了强烈的剂量效应。这项研究表明，非生物和生物因素可能不会影响基于利用根系分泌物、诱导J2孵化的分子或诱捕作物使孢囊线虫自杀性孵化的方法的开发。
