The expression of a naturally occurring, truncated allele of an α-SNAP gene suppresses plant parasitic nematode infection

Transcriptional mapping experiments of the major soybean cyst nematode resistance locus, rhg1, identified expression of the vesicular transport machinery component, alpha soluble NSF attachment protein (alpha-SNAP), occurring during defense. Sequencing the alpha-SNAP coding regions from the resistant genotypes G. max ([Peking/PI 548402]) and G. max ([PI 437654]) revealed they are identical, but differ from the susceptible G. max ([Williams 82/PI 518671]) by the presence of several single nucleotide polymorphisms. Using G. max ([Williams 82/PI 518671]) as a reference, a G -> T-2,T-822 transversion in the genomic DNA sequence at a functional splice site of the alpha-SNAP([Peking/PI 548402]) allele produced an additional 17 nucleotides of mRNA sequence that contains an in-frame stop codon caused by a downstream G -> A(2,832) transition. The G. max ([Peking/PI 548402]) genotype has cell wall appositions (CWAs), structures identified as forming as part of a defense response by the activity of the vesicular transport machinery. In contrast, the 17 nt alpha-SNAP([Peking/PI 548402]) mRNA motif is not found in G. max ([PI 88788]) that exhibits defense to H. glycines, but lack CWAs. The alpha-SNAP([PI 88788]) promoter contains sequence elements that are nearly identical to the alpha-SNAP([Peking/PI 548402]) allele, but differs from the G. max ([Williams 82/PI 518671]) ortholog. Overexpressing the alpha-SNAP([Peking/PI 548402]) allele in the susceptible G. max ([Williams 82/PI 518671]) genotype suppressed H. glycines infection. The experiments indicate a role for the vesicular transport machinery during infection of soybean by the soybean cyst nematode. However, increased GmEREBP1, PR1, PR2, PR5 gene activity but suppressed PR3 expression accompanied the overexpression of the alpha-SNAP([Peking/PI 548402]) allele prior to infection.