Tandem repeats in precursor protein stabilize transcript levels and production levels of the fungal ribosomally synthesized and post-translationally modified peptide ustiloxin B

•Core-peptide repeat number was varied in the ustiloxin precursor gene.•Ustiloxin B production increased quadratically with core-peptide repeat number.•Precursor transcript level increased linearly with core-peptide repeat number.•The intron in the ustiloxin precursor gene does not affect its transcript level.