Soybean <i>Rhg1</i> resistance to <i>Heterodera glycines</i> hinders the parasitism of <i>Pratylenchus penetrans</i>

<i>Rhg1</i> has been the most effective QTL deployed in soybeans (<i>Glycine max</i>) to control soybean cyst nematode (<i>Heterodera glycines</i>; SCN). However, the resistance mechanisms and specificity of <i>Rhg1</i> towards SCN as opposed to other plant parasitic nematodes are not well known. In this study we report that <i>Rhg1</i> can hinder the parasitism of the root lesion nematode <i>Pratylenchus penetrans</i> (Pp), which is commonly found along with SCN in northern U.S. soybean fields. Two elite public soybean varieties, carrying either <i>rhg1-a</i> + <i>Rhg4</i> or <i>rhg1-b</i>, negatively impacted Pp populations measured at 30 dpi. This contribution of <i>Rhg1</i> was more rigorously demonstrated using near isogenic lines for <i>rhg1-b</i>. Additionally, in three of the four soybean genetic backgrounds tested we observed significantly more Pp at 30 dpi when Pp were co-inoculated with SCN, consistent with a previous study. No significant changes in SCN cyst numbers upon co-inoculation with Pp were observed for any of the SCN-resistant <i>rhg1</i> lines. No nematode-induced changes in <i>Rhg1</i> transcript abundances were observed when sampling infected root sections in any of the plant genotypes, and no changes in a jasmonate response indicator were observed. However, the 3 dpi salicylate-mediated response to SCN or Pp became more robust during SCN + Pp co-infection. Multiple hypotheses for further dissection and manipulation of soybean resistance to <i>Pratylenchus</i> root lesion nematodes are suggested based on the present findings.