Transcriptomic and metabolomic analysis between Rose varieties which are resistant or susceptible to Alternaria...

Alternaria alternata is a necrotrophic fungal pathogen with a wide host range, and the black spot disease it causes on Rosa hybrida is the most serious disease, severely limiting the normal growth of Rose. However, the mechanism of this effect in Rose is not fully understood. A resistant cultivar ('DK') and a susceptible cultivar ('OB') of Rose were selected and a combined physiological, transcriptomic and metabolomic approach was used to investigate the molecular mechanisms of plant resistance to A. alternata. In this study, we found that SOD and PAL levels of Rose increased significantly after A. alternata infection, and the changes were more pronounced in the 'DK'. Kyoto Encyclopedia of the Genome (KEGG) enrichment analyses showed that differentially expressed genes (DEGs) after A. alternata infestation were enriched in plant-pathogen interaction, plant hormone signal transduction, and metabolic pathways. Two-Way Orthogonal PLS (O2PLS) analysis revealed that flavonoids and phenolic acids had the greatest effect on DEGs. Weighted gene co-expression network analysis (WGCNA) and CCA analyses further demonstrated significant correlations between flavonoid pathways and DEGs. Among the highly correlated transcription factors screened in the green module (WRKY, ERF, NAC) may be involved in flavonoid pathway-mediated resistance to black spot disease in Rose. This study provides a potential transcriptional regulatory network and thus candidate genes for resistance breeding and metabolic engineering in Rose.