Transcriptomic Insights into the Physiological Aspects of the Saprotrophic Fungus Penicillium citrinum During the Spoilage of Tobacco Leaves

Abstract

Penicillium citrinum is one of the most prevalent tobacco spoilage fungi. However, the mechanisms underlying fungal growth on tobacco leaves remain largely unknown. In this study, transcriptomic analyses were performed to reveal the genome-wide expression profiles of P. citrinum growing on tobacco leaves. First, a comparative analysis was conducted between two sets of transcriptomic data from P. citrinum growing on chemically defined media and tobacco leaves. Enrichment analyses showed that differentially regulated genes were mainly associated with carbohydrate degradation (e.g., cellulose, pectin, and xylan) and the catabolism of fatty acids and aromatic compounds. Comparative transcriptomic analyses between different time points indicated that the fungal transcriptome varied dynamically during the spoilage process, and the enriched terms were associated with small-molecule degradation and fungal development. Enrichment analyses indicated that more up-regulated genes appeared in all enriched Gene Ontology terms. Notably, more organelles significantly contributed to further fungal growth on tobacco leaves. In conclusion, P. citrinum activates a comprehensive transcriptome that changes dynamically when causing tobacco mildew.