Figure 5.

FvMAPK3 is a downstream component of low-temperature-repressed anthocyanin accumulation. A, FvMAPK3 protein levels increase upon exposure of white FvMAPK3-OE fruits to 4°C for 60 min. B, Phenotypes of detached EV-OE and FvMAPK3-OE-L1 and -L4 strawberry fruits cultivated at 10°C for the indicated number of days. Bar, 0.5 cm. C, Phenotypes of attached EV-cr and FvMAPK3-cr-C15 and -C16 strawberry fruits cultivated at 10°C for the indicated number of days. Bar: 0.5 cm. D, Relative expression levels of reported regulators involved in anthocyanin biosynthesis in detached white strawberry fruits from EV-OE and FvMAPK3-OE-L1 and -L4 plants exposed to 4°C for 24 h. Values are means ± sem of three biological replicates. Statistical significance was determined by Student’s t test (*P < 0.05, **P < 0.01). E, Relative expression levels of reported regulators involved in anthocyanin biosynthesis in detached white strawberry fruits from EV-cr and FvMAPK3-cr-C15, and -C16 plants exposed to 4°C for 24 h. Values are means ± sem of three biological replicates. Statistical significance was determined by Student’s t test (*P < 0.05, **P < 0.01). F, ABA content in detached white strawberry fruits (F. vesca, cv Fragola di Bosco) cultivated at 25°C (control conditions) or exposed to 4°C for 12, 36, or 60 h. Values are means ± sem of three biological replicates. Statistical significance was determined by Student’s t test (*P < 0.05, **P < 0.01). G, Cold-related DEGs between strawberry fruits of FvMAPK3-OE-L4 and EV-OE plants. Log₂ fold-change was used to evaluate the alteration in gene expression and direction between the two genotypes. H, FvMAPK3 interacts with FvICE1 in a Y2H assay.