Figure legends
Figure 1. Meteorological data of the experimental plot in Apple Research Institute, Gunwi (lat. 36.28°N, long. 128.47°E). (a) Change in daily minimum, mean, maximum temperature during May of 2018. (b) Comparison of daily mean temperature to 10-year annual mean.
Figure 2. Results of UPLC-QTOF-MS analysis of young apple fruit/pedicel mixed tissues undergoing abscission. (a) Volcano plot (positive : top, negative : bottom) (b) List of metabolites detected with a criteria ofp < .05 and |log2 fold change| > 1.
Figure 3. The morphological change of an excised Hongro/M9 apple tree subunit after ex-vivo cold shock followed by 168 hr of incubation at 25 °C. (a) Comparison of AZ containing pedicel tissues. (left: normal (before the incubation), middle: treatment (cold shock followed by the incubation), right: control (after the incubation). (b, c) Transmission electron microscopic images of the AZ cortical cells at proximal tissues in pedicel. Samples were observed with a LIBRA 120 transmission electron microscope at an acceleration voltage of 120 kV, magnification with 4 k (left, middle) and 6.3 k (right). (b) Treatment (168 hr of incubation following initial 2 hr of cold shock). (c) Control (168 hr after incubation without cold shock). Arrows indicate the development of cytoplasmic vesicles.
Figure 4. Spatial expression patterns of genes involved in ABA hormone biosynthesis, catabolism, and signal transduction in the cold-stressed apple subunit consisting of fruit, branch and pedicel.MDP0000336547 was used for reference gene. Data are mean ± standard error (6 ≤ n ≤ 8). * indicate significant difference in relative expression between cold treatment and control at p< .05.
Figure 5. Spatial expression patterns of genes involved in (a) cold, (b) drought, and (c) the AZ formation in the cold-stressed apple subunit consisting of a branch, pedicel and fruit. MDP0000336547 was used for reference gene. Data are mean ± standard error (6 ≤ n ≤ 8). * indicate significant difference in relative expression between cold treatment and control at p < .05.
Figure 6. Spatial expression patterns of genes involved in hormone metabolism: (a) ethylene, (b) auxin, and (c) gibberellin in the cold-stressed apple subunit consisting of branch, pedicel and fruit.MDP0000336547 was used for reference gene. Data are mean ± standard error (6 ≤ n ≤ 8). * indicate significant difference in relative expression between cold treatment and control at p< .05.
Figure 7. Spatial expression patterns of genes involved in the metabolic responses: (a) cold response, (b) ABA transport, (c) ethylene biosynthesis, and (d) cell wall modification in apple subunits consisting of a branch, pedicel and fruit. Samples were grouped by treatments as follows: Control (water); ABA (125 mg/L of ABA); Cold (initial cold shock at 4 °C for 2 hr); Cold + ABA (125 mg/L ABA followed by initial cold shock at 4 °C for 2 hr). MDP0000336547 was used for reference gene. Data are mean ± standard error (n = 6). Values with different letters differ significantly from each other atp < .05.
Figure 8. A scheme of the abscission signals induced by cold-stress in early developing apple.