Integrated transcriptomic and metabolomic analysis of Jinggang honey pomelo Yellow Spot Disease to reveal the disease defence mechanism

Jinggangshan honey pomelo, branded with "Jinggangshan," is a specialty fruit, but yellow spot disease severely affects its yield and quality. This study employed an integrated analysis of metabolomics and transcriptomics to investigate key differential metabolites (DAMs) and differentially expressed genes(DEGs) in two pomelo varieties, Jinlan (af) and Jinsha (js). A total of 1,681 DAMs were identified in the af variety, while 1,233 DAMs were identified in the js variety. The upregulated DAMs in both af and js were primarily flavonoid compounds. In the transcriptome analysis, there were 1,714 common DEGs between af and js. KEGG enrichment analysis indicated that these DEGs were significantly enriched in Plant hormone signal transduction, Plant-pathogen interaction, Phenylpropanoid biosynthesis, MAPK signaling pathway in plants, and flavonoid biosynthesis pathways. The joint analysis showed that the metabolic pathways commonly involved by DEMs and DAMs in both af and js were significantly enriched in Phenylpropanoid biosynthesis. The results revealed that in two varieties (af and js) of Jinggang honey pomelo infected with yellow spot disease, both metabolomic and transcriptomic data were enriched in the flavonoid metabolic pathway, suggesting that flavonoids may play a significant role in the defense mechanisms against this disease in Jinggang honey pomelo.