Submitted to: Bulletin of Entomological Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/15/2008
Publication Date: 4/1/2009
Citation: Gutsche A, Heng-Moss T, Sarath G, Twigg P, Xia Y, Lu G, Mornhinweg DW (2009) Gene expression profiling of tolerant barley in response to Diuraphis noxia (Hemiptera: Aphididae) feeding. Bulletin of Entomological Research. 99: 163–173. Publication Date April 2009. Interpretive Summary: Aphids are, arguably, the single most damaging group of agricultural insect pests throughout the world. Developing tolerant plants will be of great benefit to crop production. In this paper we have used genomic tools to understand the mechanistic basis of aphid-resistance in barley plants. Out data indicate that tolerant plants are able to survive aphid herbivory by increasing enzymes that can detoxify harmful cellular molecules such as reactive oxygen species. In contrast, susceptible plants do not produce these enzymes and as a consequence appear to succumb to the build-up of reactive oxygen species.
Technical Abstract: Aphids are, arguably, the single most damaging group of agricultural insect pests throughout the world. Plant resistance, specifically tolerance, is viewed as an excellent management strategy. Developing testable hypotheses based on genome-wide and more focused methods will help in understanding the molecular underpinnings of plant tolerance to aphid herbivory. As first step in this process we undertook transcript profiling with Affymetrix GeneChip Barley Genome arrays using RNA extracted from tissues of tolerant and susceptible genotypes collected at 3 h, 3 d, and 6 d after Diuraphis noxia introduction. Acquired data were compared to identify changes unique to the tolerant barley at each harvest date. A total of 4086 genes were differentially expressed over the three harvest dates in tolerant and susceptible barley in response to D. noxia feeding. Across the three harvest dates, the greatest number of genes was differentially expressed in both barleys at 3 d after aphid introduction. A total of 909 genes showed levels of change unique to the resistant barley. Many of these genes could be assigned to specific metabolic categories, including several associated plant defense and scavenging of ROS. Interestingly, several peroxidase genes were up- and down-regulated in response to D. noxia feeding on tolerant barley plants, indicating that specific peroxidases could be important for the tolerant process. These findings imply that the ability to elevate and sustain levels of ROS-scavenging enzymes along with other changes in plant metabolism could account for the survival of a tolerant genotype under high aphid pressure.