The response of the poplar transcriptome to wounding and subsequent infection by a viral pathogen

The Populus-Poplar Mosaic Virus (PopMV) pathosystem is the best characterized of all forest tree-virus interactions. The details of the host response to this virus are completely unknown. The transcript abundance for approximately 10 000 Populus genes was simultaneously interrogated using spotted cDNA microarrays. Relative transcript abundance was compared for RNA extracted from Populus leaves that were untreated, mock-inoculated leaves that were wounded by leaf abrasion and inoculated leaves that were abraded and then infected by virus. Statistical analysis of the microarray data identified suites of genes that exhibited increased or decreased transcript abundance in response to wounding, systemic PopMV infection or both together. Genes implicated in programmed cell death, and cell wall reinforcement were a major feature of the wound response, whereas genes encoding metallothionein-like proteins, and proteins implicated in cell wall remodelling were a major feature of the PopMV response. The identification of wound- and PopMV-regulated genes opens the door for future studies aimed at testing specific hypotheses related to the mechanisms used by forest trees to contend with stress.