Abstract
Dickeya solani causes soft rot in potato (Solanum tuberosum L.) tubers. We used bulk RNA-seq to compare the early transcriptional responses of the diploid F(1) genotypes from the mapping population that varied in tuber resistance to D. solani. RNA was collected from wounded tubers inoculated with D. solani (B), wounded tubers treated with sterile water (W), and non-treated tubers (NT) at 8, 24, and 48 hours post-inoculation (hpi). The largest transcriptional divergence between resistant (R) and susceptible (S) genotypes occurred at 8 hpi, with R tubers showing stronger induction of phenylpropanoid biosynthesis, phenylalanine and tyrosine metabolism, amino sugar and nucleotide sugar metabolism, isoquinoline alkaloid biosynthesis, and glutathione metabolism. Phenylpropanoid biosynthesis was dominant in R tubers, in 17 differentially expressed genes (DEGs), consistent with rapid suberin and lignin deposition as a physical barrier. RT-qPCR of nine defence-related genes corroborated the RNA-seq trends. The suberisation-associated anionic peroxidase POPA was located within a QTL for D. solani resistance on chromosome II, supporting its role as a candidate for future functional studies. This is the first transcriptome-based comparison of R and S potato genotypes challenged with D. solani, providing candidate pathways and genes that may guide future molecular breeding once their roles are validated.