show Abstracthide AbstractPenicillium oxalicum is an important biocontrol microbe in plants. A linear pentapeptide was isolated from P. oxalicum distributed in the Three Gorges river bank, and it had an extremely strong inhibitory effect on P. digitatum, a pathogen causing citrus rot. In order to explore the biosynthesis mechanism of linear pentapeptide, the cDNA libraries of three P. oxalicum strains (114-2, SG-4, SJ-3) with different pentapeptide contents were sequenced by the BGISEQ-500 platform, and the results were compared with the reference transcriptome.