Expression of highly differentially expressed genes (DEGs; fold-change > 4, FDR < 0.001) involved in photosynthesis and photorepair identified in Karlodinium veneficum treated with a combination of putrescine and ammonium (Both). Con., control; NH4, ammonium; Putr., putrescine. Gene expression was measured as TPM (transcripts per million) and normalized using the TMM (trimmed mean of M values) method, generated by Salmon (v0.11.2) [53] and embedded in Trinity (v2.8.5) [54,55]. ChlM, magnesium-protoporphyrin IX methyltransferase; FCP, fucoxanthin-chlorophyll a-c binding protein; PP264, protein LOW PHOTOSYNTHETIC EFFICIENCY 1; PAPP5, Serine/threonine-protein phosphatase 5; ChlH, magnesium-chelatase subunit ChlH; DEGP2, protease Do-like 2. SOD, superoxide dismutase. Asterisk “*” indicates the gene was also identified as a DEG in K. veneficum treated with putrescine alone. Sequences are listed in Supplementary File S5.