Abstract
BackgroundGenetic resistance of soybean [Glycine max (L.) Merr] against Aphis glycines provides effective management of this invasive pest, though the underlying molecular mechanisms are largely unknown. This study aimed to investigate genome-wide changes in gene expressions of soybean near-isogenic lines (NILs) either with the Rag5 allele for resistance or the rag5 allele for susceptibility to the aphid following infestation with soybean aphid biotype 2.ResultsThe resistant (R)-NIL responded more rapidly to aphid infestation than the susceptible (S)-NIL, with differential expressions of 2496 genes during first 12 h of infestation (hai), compared to the aphid-free control. Although the majority of the differentially expressed genes (DEGs) in the R-NIL also responded to aphid infestation in S-NIL, overall the response time was longer and/or the magnitude of change was smaller in the S-NIL. In addition, 915 DEGs in R-NIL continued to be regulated at all time points (0, 6, 12, and 48 hai), while only 20 DEGs did so in S-NIL. Enriched gene ontology of the 2496 DEGs involved in plant defense responses including primary metabolite catalysis, oxidative stress reduction, and phytohormone-related signaling. By comparing R- vs. S-NIL, a total of 556 DEGs were identified. Of the 13 genes annotated in a 120-kb window of the Rag5 locus, two genes (Glyma.13 g190200 and Glyma.13 g190600) were differentially expressed (upregulated in S- or R-NIL), and another gene (Glyma.13 g190500) was induced up to 4-fold in the R-NIL at 6 and 12 h following aphid infestation.ConclusionsThis study strengthens our understanding of the defense dynamics in compatible and incompatible interactions of soybean and soybean aphid biotype 2. Several DEGs (e.g., Glyma.13 g190200, Glyma.13 g190500, and Glyma.13 g190600) near the Rag5 locus are strong candidate genes for further investigations.
Highlights
Genetic resistance of soybean [Glycine max (L.) Merr] against Aphis glycines provides effective management of this invasive pest, though the underlying molecular mechanisms are largely unknown
The present study compared changes in mRNA abundance following aphid infestation of resistant and susceptible near-isogenic lines (NILs) developed for the Rag5 locus
The responses to aphid infestation in the two NILs significantly differed in timing of changes in gene regulation, which was triggered more quickly in the R-NIL
Summary
Genetic resistance of soybean [Glycine max (L.) Merr] against Aphis glycines provides effective management of this invasive pest, though the underlying molecular mechanisms are largely unknown. Soybean aphid (Aphis glycines Matsumura) is a phloemfeeding insect of soybean [Glycine max (L.) Merr] that is native to East Asia [1]. It was first found in soybean fields in northern United States in 2000 [2], and the aphid rapidly spread over the main soybean growing areas in both the United States and Canada [3]. It is a serious invasive pest of soybean in North America as well as a vector of several. Beneficial insect populations can be negatively affected due to intensive uses of chemicals [12, 13]
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