Because of the developmental similarities between root nodules induced by symbiotic rhizobia and root galls formed by parasitic nematodes, we investigated the involvement of nodulation genes in the infection of Medicago truncatula by the root knot nematode (RKN), Meloidogyne javanica. We found that gall formation, including giant cell formation, pericycle and cortical cell division, as well as egg laying, occurred successfully in the non-nodulating mutants nfp1 (nod factor perception1), nin1 (nodule inception1) and nsp2 (nodulation signaling pathway2) and the cytokinin perception mutant cre1 (cytokinin receptor1). Gall and egg formation were significantly reduced in the ethylene insensitive, hypernodulating mutant skl (sickle), and to a lesser extent, in the low nodulation, abscisic acid insensitive mutant latd/nip (lateral root-organ defective/numerous infections and polyphenolics). Despite its supernodulation phenotype, the sunn4 (super numeric nodules4) mutant, which has lost the ability to autoregulate nodule numbers, did not form excessive numbers of galls. Co-inoculation of roots with nematodes and rhizobia significantly reduced nodule numbers compared to rhizobia-only inoculated roots, but only in the hypernodulation mutant skl. Thus, this effect is likely to be influenced by ethylene signaling, but is not likely explained by resource competition between galls and nodules. Co-inoculation with rhizobia also reduced gall numbers compared to nematode-only infected roots, but only in the wild type. Therefore, the protective effect of rhizobia on nematode infection does not clearly depend on nodule number or on Nod factor signaling. Our study demonstrates that early nodulation genes that are essential for successful nodule development are not necessary for nematode-induced gall formation, that gall formation is not under autoregulation of nodulation control, and that ethylene signaling plays a positive role in successful RKN parasitism in M. truncatula.

由于共生根瘤菌引起的根瘤与寄生线虫形成的根gall之间的发育相似性，我们研究了结瘤基因在感染根瘤菌中的作用。 紫花苜蓿 通过根结线虫（RKN） 爪蟾。我们发现非结节突变体成功发生了胆汁形成，包括巨细胞形成，周细胞和皮层细胞分裂以及卵生。nfp1 （点头因子感知1）， 宁1 （结节开始1）和 nsp2 （结瘤信号通路2）和细胞分裂素感知突变体 cre1 （细胞分裂素受体1）。乙烯不敏感，高结瘤突变体的胆和卵形成显着减少l （镰刀），并在较小程度上降低了脱落酸不敏感突变体 latd / nip （侧根器官缺损/大量感染和多酚）。尽管有超结节表型，sunn4 （超级数字结节4）突变体失去了自动调节结节数量的能力，但并未形成过多的胆汁。与仅根瘤菌接种的根相比，根与线虫和根瘤菌的共同接种显着减少了结节数，但仅在高结瘤突变体中l。因此，这种影响很可能受到乙烯信号的影响，但不可能由胆结节之间的资源竞争来解释。与仅线虫感染的根相比，与根瘤菌的共同接种也减少了胆量，但仅在野生型中。因此，根瘤菌对线虫感染的保护作用并不明显取决于根瘤数或Nod因子信号。我们的研究表明，对于成功的根瘤形成而言，早期结瘤基因对于线虫诱导的胆汁形成不是必需的，胆汁形成不受结瘤控制的自动调节，并且乙烯信号传导在成功的RKN寄生中起着积极的作用。run。