Transcriptome Analysis Reveals Genes Involved in Responses of Eucalyptus to Gall Wasp Infestation

Leptocybe invasa is a gall wasp causing significant damage to Eucalyptus species. This study used RNA sequencing (RNA-seq) to identify differentially expressed genes (DEGs) associated with early L. invasa infestation in eucalyptus parents and their F1-progenies. A total of 14,648 significant DEGs were identified from U22-tolerant and C153-susceptible parents, and extremely tolerant and susceptible pools of their F1-progenies. A total of 324/632 and 182/205 DEGs specific for the tolerant group and the susceptible group were up-regulated, respectively. Expression analysis by qRT-PCR of the selected DEGs was comparable with the results of RNA-seq. Expression analysis of the selected genes using the top five progenies from each pool was consistent with that in the parents. Three genes (RCA, SUI1, GCN5) were up-regulated after infestation in all tested tolerant plants, suggesting their important roles in the tolerant phenotype. Using expression and STRING analysis, our results suggest that early response at three days after gall wasp infestation increased protein and terpenoid synthesis, and increased transportation of these molecules. In addition, wounding also increased photosynthesis and glycolysis. These processes involved the interaction of several plant hormones, such as JA, Auxin, and ABA. The information obtained from this study could be useful for future Eucalyptus breeding programs