Comparative transcriptome analysis of Aspergillus niger revealed its biocontrol mechanisms in response to the guava wilt pathogen Fusarium oxysporum f. sp. psidii

Wilt is one of the major destructive diseases in guava cultivation worldwide. Biocontrol agent Aspergillus niger been recognized for its efficacy against various plant pathogens including guava wilt disease. This biocontrol fungus has been widely studied for its mycoparasitic and antibiosis mechanisms. Still, a notable gap exists in literature regarding the molecular mechanisms and biosynthetic pathways underlying biocontrol activity when challenged with guava wilt pathogen. In this investigation, we conducted comprehensive global RNA sequencing, which generated a total of 35.16 GB data, comprising 18-22 million reads having 52-54 % GC content. Over 55,464 transcripts displayed differential expression profiles during the interaction of biocontrol and the pathogen, out of that 5285 transcripts were expressed at FC2 and Pval 0.05. They were mainly associated with catalytic activity (48.45 %), protein or DNA binding activity (44.9 %), transporter activity (8.2 %), and transcription regulator activity (5.5 %). In the biological process category, 36.5 % and 34.7 % of transcripts were linked to "metabolic" and "cellular processes," respectively. The upregulated DEGs were predominantly linked hydrolytic activity and secondary metabolite production, encompassing AB hydrolases, cyanate hydratase, Isochorismatase hydrolase, galacturan 1,4-alpha-galacturonidase B, Esterase/Lipase, MFS monosaccharide transporter, ATP-binding cassette transporter, polyamine transporter 3, endoglucanase A, and non-ribosomal siderophore peptide synthase (SidC). Our investigation highlighted that the biocontrol mechanism primarily involves the active participation of hydrolytic enzymes, transporters, transcription factors, and secondary metabolites. Additionally, the data were validated using RT-qPCR, affirming the consistency of RNA-seq findings. This study represents the inaugural effort to elucidate the biocontrol mechanism of A. niger against F. oxysporum f. sp. psidii using the RNA-seq approach. The findings shed light on the antagonistic mechanisms of A. niger at molecular level, enhancing our comprehension of A. niger as a biocontrol agent and deepening our exploration biocontrol and pathogen interactions.