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

Wei Guo,Yongqing Jiao,Qingbo You,Zeyu Li,Xinjie Shen,Xinan Zhou,Yihui Cheng,Feng Zhang,Aili Bao,Jingsheng Chen,Wei Zhao

doi:10.1111/mpp.12753

Abstract

Summary 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.

Highlights

Soybean cyst nematode (SCN; Heterodera glycine Ichinohe) is an important plant-parasitic pest in soybean [Glycine max (L.)Merrill] and causes substantial damage to soybean production worldwide (Niblack et al, 2006)
The alignment of protein sequences revealed that Rhg1-GmAAT shared 58.72% amino acid identity with Arabidopsis vacuolar amino acid transporter 6C (AVT6C) and 58.31% amino acid identity with AtAVT6D
Rhg1-GmAAT was ubiquitously expressed in the roots, stems, leaves, flowers, cotyledons and stem apex, with the expression of Rhg1-GmAAT being highest in the roots, stems and cotyledons (Fig. 1a)

Summary

Introduction

Soybean cyst nematode (SCN; Heterodera glycine Ichinohe) is an important plant-parasitic pest in soybean [Glycine max (L.)Merrill] and causes substantial damage to soybean production worldwide (Niblack et al, 2006). Other than rotation with non-host crop plants, the breeding of SCN-resistant soybean varieties is the most effective and environmentally friendly technique for the control of SCN (Cook, 2004). Two different alleles exist at the Rhg locus: Rhg1-a, which is from Peking, and Rhg1-b, which is from PI88788 (Concibido et al, 2004; Kim et al, 2010) These two alleles have distinctive mechanisms of resistance to SCN. Three genes are responsible for the resistance provided by Rhg1-b: Glyma.18G022400 (Rhg1GmAAT), which encodes a predicted amino acid transporter; Glyma.18G022500 (GmSNAP18), which encodes a predicted α-soluble N-ethylmaleimide-sensitive factor (NSF) attachment protein (α-SNAP); and Glyma.18G022700 (Rhg1-GmWI12), which encodes a putative wound-induced protein (Cook et al, 2012). The characterization of these two genes, as well as the understanding of how all three genes coordinately function to provide resistance to SCN, is lacking

Results

Discussion

Conclusion