Identification of soybean herbivory-regulated genes and a transgenic investigation of their potential in insect resistance

Abstract

Soybean (Glycine max) is an important economic crop worldwide that has been affected by common cutworm (Spodoptera litura Fabricius) in southern China. In this study, RNA-Seq was applied to extend our understanding of the functional complexity of the soybean transcriptome in response to insects. Totals of 1004 and 1580 unigenes were differentially expressed in resistant and susceptible soybean lines, respectively. The functional classification of these unigenes identified the same significant categories as in the previous microarray results, most of which were related to stress and defense responses. A qRT-PCR analysis of 21 selected genes confirmed the results of the RNA-Seq analysis. The integration of RNA-Seq, microarray and qRT-PCR data highlighted GmVSPβ and GmN:IFR as two candidate genes that may confer insect resistance. A functional analysis of GmVSPβ and GmN:IFR revealed a certain degree of resistance to common cutworm in overexpressing tobacco lines, and GmVSPβ was more efficient in this role, which may be associated with JA signaling regulation and nicotine biosynthesis. Taken together, our studies provide an overview and survey of the genes that are involved in insect resistance. Transgenic studies of two herbivory-regulated genes demonstrated their function in insect resistance and indicated their potential application to enhance insect resistance in crops.