Benzothiadiazole induced changes in the transcriptome and regulation of banana fruit ripening and disease resistance

Benzothiadiazole (BTH) induces plant disease resistance and delays fruit ripening, but its possible mechanism of action remains unclear. Therefore this study investigated the effects of BTH on ripening and disease incidence in banana (Musa spp.) fruit. Our results showed that using BTH delayed ripening and maintained fruit firmness by inhibiting the enzymes involved in softening. BTH also delayed and reduced the occurrence of anthracnose caused by Colletotrichum musae during the ripening process. Transcriptome analysis identified 10,430 differen-tially expressed genes (DEGs) during the ripening process compared with freshly harvested fruit. Many DEGs were identified between the BTH and control group or prochloraz treatment, but only a few DEGs were found in the prochloraz treatment compared to the control group. A Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that the DEGs induced by the BTH treatment were primarily enriched in the synthesis of terpenoid quinones, plant-pathogen interaction, plant hormone signal transduction, phenylpropanoid biosyn-thesis, phenylalanine metabolism, peroxisome, and fatty acid biosynthesis among other pathways. BTH also induced the expression of many transcription factor (TF) families, including those in the WRKY, NAC, MYB and bHLH families, with the WRKY family being the most enriched. The WRKY TF interacts with many ripening-and secondary metabolism-related genes to regulate fruit ripening and disease resistance. Our results showed that, compared with the fungicide prochloraz, BTH alters the transcripts of the genes related to hormone signalling, secondary metabolism and resistance in the banana peel, and key TFs, thereby delaying fruit ripening, enhancing fruit resistance, and maintaining fruit quality.

Automated summary

BTH delays fruit ripening and maintains fruit firmness by inhibiting enzymes involved in softening. It also delays and reduces the occurrence of anthracnose caused by Colletotrichum musae.