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 with 396 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 up-regulated in the Rag2 line were annotated as involved in cell wall, secondary and hormone metabolism, as well as in stress, signaling and transcriptional responses. Genes down-regulated in the Rag2 line were annotated as 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.