Soybean Resistance Locus Rhg1 Confers Resistance to Multiple Cyst Nematodes in Diverse Plant Species.

Abstract

Cyst nematodes consistently threaten agricultural production, causing billions of dollars in losses globally. The Rhg1 (resistance to Heterodera glycines 1) locus of soybean (Glycine max) is the most popular resistance source used against soybean cyst nematodes (H. glycines). Rhg1 is a complex locus that has multiple repeats of an ≈30-kilobase segment carrying three genes that contribute to resistance. We investigated whether soybean Rhg1 could function in different plant families, conferring resistance to their respective cyst nematode parasites. Transgenic Arabidopsis thaliana and potato (Solanum tuberosum) plants expressing the three soybean Rhg1 genes were generated. The recipient Brassicaceae and Solanaceae plant species exhibited elevated resistance to H. schachtii and Globodera rostochiensis and to G. pallida, respectively. However, some negative consequences including reduced root growth and tuber biomass were observed upon Rhg1 expression in heterologous species. One of the genes at Rhg1 encodes a toxic version of an alpha-SNAP protein that has been demonstrated to interfere with vesicle trafficking. Using a transient expression assay for Nicotiana benthamiana, native Arabidopsis and potato alpha-SNAPs (soluble NSF [N-ethylamine sensitive factor] attachment protein) were found to compensate for the toxicity of soybean Rhg1 alpha-SNAP proteins. Hence, future manipulation of the balance between Rhg1 alpha-SNAP and the endogenous wild-type alpha-SNAPs (as well as the recently discovered soybean NSF-RAN07) may mitigate impacts of Rhg1 on plant productivity. The multispecies efficacy of soybean Rhg1 demonstrates that the encoded mechanisms can function across plant and cyst nematode species and offers a possible avenue for engineered resistance in diverse crop species.