Fig 1.
Genes identified in the metabolism network of pigments, folic acid and ascorbic acid during strawberry fruit ripening.
Pathways, including anthocyanin, carotenoid, ascorbic acid and folic acid biosynthesis and chlorophyll degradation, are shown. Genes encoding enzymes with blue names were significantly differentially expressed among samples, and those encoding enzymes with purple names were identified as non-significantly differentially expressed. The chloroplast is separated from the plastid to clearly illustrate the chlorophyll breakdown pathway. Abbreviations: (anthocyanin biosynthetic pathway) 3-deoxy-7-phosphoheptulonate synthase, DAHPS; 3-dehydroquinate synthase, DHQS; 3-dehydroquinate dehydratase/shikimate dehydrogenase, DHD/SHD; Shikimate kinase, SK; 5-enolpyruvylshikimate-3-phosphate synthase, EPSPS; chorismate synthase, CS; chorismate mutase, CM; phenylalanine ammonia lyase, PAL; cinnamate 4-hydroxylase, C4H; p-coumarate ligase, 4CL; chalcone synthase, CHS; chalcone isomerase, CHI; flavanone 3-hydroxylase, F3H; dihydroflavonol 4-reductase, DFR; anthocyanidin synthase, ANS; glucosyltransferase, GT; (carotenoid biosynthetic pathway) 1-deoxy-D-xylulose-5-phosphate synthase, DXS; 1-deoxy-D-xylulose-5-phosphate reductoisomerase, DXR; 2-C-methyl-D-erythritol 4-phosphate cytidylyltransferase, CMS; 4-diphosphocytidyl-2-C-methyl-D-erythritol kinase, CMK; 2-C-methyl-D-erythritol 2,4-cyclodiphosphate synthase, MCS; isopentenyl-diphosphate delta-isomerase, IPI; geranyl diphosphate synthase, GGPS; geranylgeranyl reductase, GGR; phytoene synthase, PSY; phytoene desaturase, PDS; zeta-carotene isomerase, Z-ISO; zeta-carotene desaturase, ZDS; carotenoid isomerase, CRTISO; lycopene beta cyclase, LCYB; zeaxanthin epoxidase, ZEP; violaxanthin de-epoxidase, VDE; acetyl-CoA C-acetyltransferase, ACAT; hydroxymethylglutaryl-CoA synthase, HMGCS; mevalonate kinase, MVK; phosphomevalonate kinase, PMVK; farnesyl diphosphate synthase, FPPS. (Chlorophyll breakdown pathway) pheophorbide a oxygenase, PAO; red chlorophyll catabolite reductase, RCCR. (ascorbic acid biosynthetic pathway) glucose-6-phosphate isomerase, GPI; mannose-6-phosphate isomerase, MPI; phosphomannomutase, PMM; mannose-1-phosphate guanyltransferase, GMPPB; GDP-mannose 3,5-epimerase, GME; GDP-L-galactose phosphorylase, GGP; L-galactose dehydrogenase, GDH; L-galactono-1,4-lactone dehydrogenase, GLDH. (folate biosynthetic pathway) para-aminobenzoate synthase, pABS; dihydropteroate synthase, DHPS; gamma-glutamyl hydrolase, GGH. For the abbreviations of other metabolites, please refer to the manuscript.
Fig 2.
The effects of ABA and NDGA treatment on strawberry fruit ripening.
(A) Morphological evaluation of the strawberry fruit in response to ABA or NDGA treatment. Changes of secondary metabolites levels in the receptacle: (B) total anthocyanin content; (C) β-carotene content; (D) chlorophyll content; (E) total folate content; and (F) ascorbic acid content. Fourteen day-old strawberry fruits after anthesis (set as day 0) were injected with chemical solutions of ABA, NDGA and distilled water for pharmacological investigation. Error bars indicate the standard deviation (SD) of means (n = 3). Bar = 1 cm. Different lowercase letters represent statistical significance (P < 0.05).
Fig 3.
Differentially expressed genes involved in the anthocyanin biosynthesis pathway in response to ABA or NDGA treatment.
CK, ABA, and NDGA represent fruit treated with water, ABA, or NDGA, respectively. Only the receptacle samples were collected for RNA-seq analysis. Red and green colors mean up- and down-regulated expression of genes, respectively. The number in each sample name represents the collection day.
Fig 4.
Differentially expressed genes involved in the carotenoid and folate biosynthesis pathways and the chlorophyll degradation pathway in response to ABA or NDGA treatment.
(A) Gene expression in the carotenoid biosynthetic pathway. (B) Gene expression in the chlorophyll breakdown and folate biosynthetic pathways. CK, ABA, and NDGA represent fruit treated with water, ABA, or NDGA, respectively. Only the receptacle samples were collected for RNA-seq analysis. Red and green colors mean up- and down-regulated expression of genes, respectively. The number in each sample name represents the collection day.
Fig 5.
Differentially expressed genes involved in the ascorbic acid biosynthesis pathway.
CK, ABA, and NDGA represent fruit treated with water, ABA, or NDGA, respectively. Only the receptacle samples were collected for RNA-seq analysis. Red and green colors mean up- and down-regulated expression of genes, respectively. The number in each sample name represents the collection day.