Transcriptomics and metabolomics analysis reveal the key regulator in BTH-induced fruit resistance of banana

Benzothiadiazole (BTH) is a plant resistance inducer that effectively delays ripening and senescence in fruits. To understand its possible mechanism, transcriptomics and metabolomics analyses were performed on banana (Musa spp.) fruit treated with BTH after their inoculation with the fungal pathogen Colletotrichum musae. A total of 1,747 differentially expressed genes (DEGs) were identified, and 1,160 were up- and 587 downregulated between the BTH and control conditions. These DEGs were highly enriched in metabolic pathways related to disease resistance, such as phenylpropanoid biosynthesis, flavonoids, and starch and sucrose metabolism. A metabolome analysis identified 138 differentially accumulated metabolites (DAMs) of which 73 were upregulated and 65 downregulated between the BTH and control conditions. Flavonoids were significantly upregulated DAMs. Transcriptome and metabolome analyses showed that the lignin biosynthesis and flavonoid biosynthesis pathways played important roles in the disease resistance of banana fruit induced by BTH by upregulating the expression of PAL, 4CL, PER, CHS, FLS, and FL3H. Moreover, WRKY transcription factors (TFs) also played key roles in this process of resistance by mediating genes related to disease resistance, such as PR1, PR1c, TLPH, PTI5, and other genes. Our results suggested that the BTH treatment significantly changed the expression of transcripts and metabolites related to the hormone signaling, secondary metabolism, disease resistance, and key TFs, which induced the disease resistance and delayed the ripening process. The insights into these molecular mechanisms also provide potential targets for genetic or chemical approaches to further enhance fruit quality and resistance.