The soybean Rhg1 amino acid transporter gene alters glutamate homeostasis and jasmonic acid-induced resistance to soybean cyst nematode

Rhg1 (resistance to Heterodera glycines 1) is an important locus that contributes to resistance against soybean cyst nematode (SCN; Heterodera glycines Ichinohe), which is the most economically damaging disease of soybean worldwide. Simultaneous overexpression of three genes encoding a predicted amino acid transporter, an α-soluble N-ethylmaleimide-sensitive factor attachment protein (α-SNAP) and a predicted wound-induced protein resulted in resistance to SCN provided by this locus. However, the roles of two of these genes (excluding α-SNAP) remain unknown. Here, we report the functional characterization of Glyma.18G022400, a gene at the Rhg1 locus that encodes the predicted amino acid transporter Rhg1-GmAAT. Although the direct role of Rhg1-GmAAT in glutamate transport was not demonstrated, multiple lines of evidence showed that Rhg1-GmAAT impacts glutamic acid tolerance and glutamate transportation in soybean. Transcriptomic and metabolite profiling indicated that overexpression of Rhg1-GmAAT activated the jasmonic acid (JA) pathway. Treatment with a JA biosynthesis inhibitor reduced the resistance provided by the Rhg1-containing PI88788 to SCN, which suggested that the JA pathway might play a role in Rhg1-mediated resistance to SCN. Our results could be helpful for the clarification of the mechanism of resistance to SCN provided by Rhg1 in soybean.