Transcriptomic profiling of interspecific hybrid in response to Phytophthora nicotianae infection in betelvine

Phytophthora nicotianae is highly pathogenic and major constraint in betelvine crop production. To examine the resistance of 13 interspecific hybrids to P. nicotianae , revealing significant variability in disease severity. IIHRPBIH9 exhibited the lowest disease severity and infection rate, whereas the IIHRBV170 was susceptible to infection. RNA sequencing was employed in IIHRPBIH9 and IIHBV170, which generated 6.62 GB of data, yielding 27,774 refined transcripts and 16,329 contigs. The leaf samples for RNA isolation were collected at 0 and 72 hours after inoculation (hai). 8561 and 10188 differentially expressed genes (DEGs) were identified in uninoculated and inoculated resistant (IIHRPBIH9) interspecific hybrid and susceptible variety, respectively. Gene ontology (GO) enrichment and KEGG pathway analyses highlighted key defense-related pathways, such as superoxide radicals degradation and jasmonic acid biosynthesis. Up-regulated genes included peroxidase 5-like protein and pathogenesis-related proteins, while down-regulated genes like LRR receptor-like kinase suggested susceptibility mechanisms. Heat maps revealed significant up-regulation of defense genes in inoculated resistant samples. The putative candidate genes were validated through qRT-PCR, confirming significant up-regulation of selected defense genes, and elucidating the molecular mechanisms of resistance and susceptibility. The transcriptome profile and putative candidate resistant and susceptible genes identified can be explored in breeding betelvine for P. nicotianae resistance.