Transcriptome Changes in Barley Chromosome Addition Lines of Common Wheat Caused by Gall-Inducing Leafhopper Feeding

Maize orange leafhopper feeding induces galls in various Poaceae, including wheat, but not in barley. Previously, we investigated the effects of barley chromosome addition on the susceptibility of wheat to leafhopper feeding. The results showed that the barley chromosome 3H reduced the degree of gall induction, while chromosome 5H promoted more severe gall induction than that by normal wheat (‘Chinese Spring’ [CS]). To better understand the mechanism(s) of gall induction in wheat, we conducted transcriptome analysis after leafhopper feeding in the barley (‘Betzes’) chromosome addition lines of wheat (CS). Seedlings of CS and barley chromosome addition lines were exposed to 5 leafhoppers for 24 h. Furthermore, CS was exposed to 2, 4, 8, and 16 leafhoppers to examine the density effect of leafhoppers. As the control, CS was exposed to 5 planthoppers, which do not induce gall in wheat. Total RNAs were extracted from seedlings containing shoot apex. To obtain the overall gene expression profiles, a wheat oligo-DNA microarray was used. Of the 43,803 probes in the microarray, 10,504 probes showed more than two-fold changes in the expression levels after leafhopper feeding. The number of up-regulated genes after leafhopper feeding was greater than that of down-regulated genes. In the susceptible lines (4H, 5H, and 7H), the number of down-regulated genes was greater than that in the resistant lines. Some gene expressions that were related to degrees of gall induction were annotated as transcription factors, implying that these genes play regulating roles in gall induction in wheat.