Fig. 1
Characterization of PbrADC1 gene involved in superficial scald development via regulating putrescine biosynthesis. a Alternation of putrescine metabolism upon superficial scald development in ‘Yali’ fruit. (a-i) Visual quality change. (a-ii) Putrescine level. (a-iii) Expression profiles of 21 putrescine-metabolism-related genes. ‘Yali’ fruit, with and without superficial scald, were sampled after -0.5 ℃ for 180 d followed by a 7-d shelf life at 20 ℃. b Putrescine content and PbrADC1 expression abundance in ‘Yali’ fruit of different superficial scald severities. (b-i) Putrescine content. (b-ii) PbrADC1 mRNA abundance. ‘Yali’ fruit, with different superficial scald severities (Hui et al. 2016), were sampled after -0.5 ℃ for 180 d followed by a 7-d shelf life at 20 ℃. The expression abundance of PbrADC1 in the unscalded fruit (Severity 0) was set as 1.0 for RT-qPCR assay. c Dynamic change of putrescine metabolism during cold storage of ‘Dangshansuli’ fruit. ‘Dangshansuli’ fruit were sampled every 60-d storage at 0.5 ℃ followed by a 7-d shelf life at 25 ℃. d Impact of exogenous putrescine treatment on superficial scald development in pear fruit. (d-i) Visual quality change. (d-ii) Superficial scald incidence and index. ‘Yali’ fruit were randomly divided into three groups for different treatments: 0.0 (H2O), 2.0-mM, and 5.0-mM putrescine immersion for 15 min before 210-d storage at -0.5 ℃ followed by a 7-d shelf life at 20 ℃. A total of 21 putrescine-metabolism-related genes were characterized from the P. bretschneideri Rehd. genome (Table S2). Data represent the mean values of three biological replicates, except for the transcriptome assay of the (un) scalded ‘Yali’ fruit (two replicate). Different lowercase letters meant significance between samples (p < 0.05). Color scale represented normalized log2-transformed (FPKM + 1), where red indicated a high level, blue represented a low level, and white indicated a medium level. Absolute correlation coefficients between attributes ≥ 0.8 were visualized in the heatmap, where red lines demonstrated extremely strong positive correlations, while green demonstrated extremely strong negative associations