Analysis of transcriptome differences between two clones of <i>Populus</i> section <i>Aigeiros</i> after insect infestation

Insect resistance is an inherent characteristic of plants and determined by genotypic differences across plants. In this study, we determined differences in the gene expression patterns between two clones of Populus section Aigeiros after insect infestation and elucidated the mechanism of resistance induced by insect feeding. We performed differential gene expression (DEG) analysis by using Illumina Hiseq 2000 high-throughput sequencing of leaf samples from the upper, middle, and lower parts of Populus euramericana cv. ‘Neva’ (“P107”) and P. deltoids ‘Chuangxin’ (“P17-2”) infested with the insect. We selected 3,462 DEGs through a comparison between “P107” and “P17-2” (A vs. B). Based on the gene ontology analysis, the identified DEGs were functionally annotated, which revealed 20, 23, and 22 functional categories of “biological process”, “cellular component”, and “molecular function”, with enrichment mainly in “cellular process”, “cell part”, and “binding functions”, respectively. After insect feeding, the damaged leaves of “P107” and “P17-2” showed different degrees of resistance, along with upregulated defense gene expressions, reduced nutrient accumulation and photosynthesis, and enhanced secondary metabolite biosynthesis. This study provides a molecular basis for understanding the mechanism underlying insect resistance in plants.