Co-regulation of the <i>Glycine max</i> soluble N-ethylmaleimide-sensitive fusion protein attachment protein receptor (SNARE)-containing regulon occurs during defense to a root pathogen

Genes functioning in membrane fusion were originally identified genetically in <i>Saccharomyces cerevisiae</i> and are found in all eukaryotes. Components of the unit, soluble N-ethylmaleimide-sensitive fusion protein attachment protein receptor (SNARE), function in the plant genetic model <i>Arabidopsis thaliana</i> during its defense to shoot pathogens. Regarding defense, little is understood about SNARE in roots or its regulation. Experiments in <i>Glycine max</i> (soybean) have provided an opportunity to perform such studies, revealing that SNARE genes are expressed under natural conditions in root cells undergoing defense to parasitism by the nematode <i>Heterodera glycines</i>. Presented here, the <i>G. max</i> homolog of <i>S. cerevisiae</i> suppressor of sec1 (<i>SSO1</i>), identified genetically in <i>A. thaliana</i> as <i>PENETRATION1</i> (<i>PEN1</i>) and named in its genomic annotation as syntaxin 121 (SYP121) functions in the resistance of <i>G. max</i> to <i>H. glycines</i>. Genetic experiments demonstrate Gm-SYP121 is co-expressed with homologs of other SNARE genes exhibiting measurable transcript levels in infected cells undergoing resistance. These genes include synaptosomal-associated protein 25, homologous to <i>A. thaliana SNAP33</i> (SNAP-25/<i>SNAP33</i>/<i>SEC9</i>); mammalian uncoordinated-18 (MUNC18/<i>SEC1</i>); synaptotagmin/tricalbin-3 (SYT/<i>TCB3</i>); synaptobrevin/vesicle associated membrane protein/<i>YKT6</i>/<i>SEC22</i> (SYB/<i>VAMP</i>/<i>YKT6/SEC22</i>); N-ethylmaleimide-sensitive fusion protein (NSF/<i>SEC18</i>) and alpha-soluble N-ethylmaleimide-sensitive fusion protein associated protein (α-SNAP/<i>SEC17</i>). Experiments show each SNARE component functions in resistance. In contrast, a coatomer zeta/retrieval3 (Cζ/<i>RET3</i>) homolog known to function in retrograde transport within and between the Golgi and endoplasmic reticulum does not appear to function in resistance. Experiments show that SNARE is co-regulated along with a β-glucosidase having homology to <i>PEN2</i> and an ATP binding cassette transporter exhibiting homology to <i>PEN3</i>.