Identification of Soybean Proteins and Genes Differentially Regulated in Near Isogenic Lines Differing in Resistance to Aphid Infestation

Soybean
aphid is an important pest causing significant yield losses.
The Rag2 locus confers resistance to soybean aphid
biotypes 1 and 2. Transcriptomic and proteomic analyses were done
over a 48 h period after aphid infestation using near isogenic lines
(NILs) differing at the Rag2 locus. Comparing the Rag2 and/or rag2 lines identified 3445
proteins, of which 396 were differentially regulated between the two
lines, including proteins involved in cell wall metabolism, carbohydrate
metabolism, and stress response. RNA-seq transcriptomic analysis identified
2361 genes significantly regulated between the resistant and susceptible
lines. Genes upregulated in the Rag2 line were annotated
as being involved in cell wall, secondary, and hormone metabolism
as well as in stress, signaling, and transcriptional responses. Genes
downregulated in the Rag2 line were annotated as
being involved in photosynthesis and carbon metabolism. Interestingly,
two genes (unknown and mitochondrial protease) located within the
defined Rag2 locus were expressed significantly higher
in the resistant genotype. The expression of a putative NBS-LRR resistant
gene within the Rag2 locus was not different between
the two soybean lines, but a second NBL-LRR gene located just at the
border of the defined Rag2 locus was. Therefore,
this gene may be a candidate R gene controlling aphid resistance.