Characterization of the Soluble NSF Attachment Protein gene family identifies two members involved in additive resistance to a plant pathogen

Naoufal Lakhssassi,Vincent Colantonio,Khalid Meksem,Sadia Bekal,Kris Lambert,Zhou Zhou,Shiming Liu,Abdelali Barakat

doi:10.1038/srep45226

Abstract

Proteins with Tetratricopeptide-repeat (TPR) domains are encoded by large gene families and distributed in all plant lineages. In this study, the Soluble NSF-Attachment Protein (SNAP) subfamily of TPR containing proteins is characterized. In soybean, five members constitute the SNAP gene family: GmSNAP18, GmSNAP11, GmSNAP14, GmSNAP02, and GmSNAP09. Recently, GmSNAP18 has been reported to mediate resistance to soybean cyst nematode (SCN). Using a population of recombinant inbred lines from resistant and susceptible parents, the divergence of the SNAP gene family is analysed over time. Phylogenetic analysis of SNAP genes from 22 diverse plant species showed that SNAPs were distributed in six monophyletic clades corresponding to the major plant lineages. Conservation of the four TPR motifs in all species, including ancestral lineages, supports the hypothesis that SNAPs were duplicated and derived from a common ancestor and unique gene still present in chlorophytic algae. Syntenic analysis of regions harbouring GmSNAP genes in soybean reveals that this family expanded from segmental and tandem duplications following a tetraploidization event. qRT-PCR analysis of GmSNAPs indicates a co-regulation following SCN infection. Finally, genetic analysis demonstrates that GmSNAP11 contributes to an additive resistance to SCN. Thus, GmSNAP11 is identified as a novel minor gene conferring resistance to SCN.

Highlights

The majority of crop species appears to be polyploids as a result of duplication or hybridization events
Investigation of the Williams 82 soybean genome indicates that the GmSNAP gene family is composed of five members located on chromosomes 02 (Glyma.02g260400), 14 (Glyma.14g054900), 11 (Glyma.11g234500), and 18 (Glyma.18g022500), all encoding 289 amino acid proteins, except one in chromosome 09 (Glyma.09g279400) encoding a 290aa protein
GmSNAP18 was previously reported to be involved in soybean cyst nematode (SCN) resistance, along with an amino acid transporter (AAT) and a wound inducible protein (WI12)[20]

Summary

Introduction

The majority of crop species appears to be polyploids as a result of duplication or hybridization events. Two types of SCN resistant soybean lines have been used by soybean breeders, the PI88788 type of resistance which requires three genes together at the rhg[1] locus for its function: a Soluble NSF Attachment Protein (α-SNAP), an Amino Acid Transporter (AAT) and a Wound-Inducible domain (WI12)[20]; and the Peking type of resistance requires two genes: the GmSNAP18 at the rhg[1] locus and the GmSHMT08 at the Rhg[4] locus[25,26]. A SCN gene encoding a bacterial-like protein containing a putative SNARE domain (HgSLP-1), an esophageal-gland protein that is secreted by the nematode during plant parasitism, has been suggested to physically interact with the Rhg[1] α-SNAP in SCN resistance[28]. The authors suggested that HgSLP-1 protein may function as an avirulence protein and it helps SCN evade host defenses when absent

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Conclusion