Fig. 1.

Overexpression (OE) of sucrose non‐ferment 1 related protein kinase 2 MdSnRK2.4 and MdSnRK2.9 promotes ethylene (ETH) production and fruit ripening in apple [Correction after first publication 22 March 2022: the gene name in the preceding sentence has been corrected.]. (a) Relative expression of MdSnRK2s family genes during apple fruit development and ripening. (b) Screening for MdSnRK2 family members involved in regulating ETH production. MdSnRK2 genes were overexpressed in apple callus cells. ETH content was determined at 0, 12 and 24 h post‐infection with Agrobacterium. EV, empty vector. (c) Immunoblot analysis of MdSnRK2.4 and MdSnRK2.9 protein levels using specific antibodies to MdSnRK2.4 and MdSnRK2.9. Actin levels were used as an input control. (d) Phosphorylation level of MdSnRK2.4/2.9 throughout apple fruit development and ripening. Protein extracts were separated in a phos‐tag gel. Phosphorylated and nonphosphorylated MdSnRK2.4/2.9 were detected with anti‐MdSnRK2.4/2.9 antibody and quantitated by densitometry using ImageJ. In (a, b), values are means ± SD of three biological replicates. Different letters in (a) indicate significant differences according to Tukey’s honestly significant difference (HSD) test (P < 0.01). The asterisks in (b) indicate significant differences compared with the EV control (*, P < 0.05; **, P < 0.01; Student’s t‐test). DPA, d post‐anthesis. See also Supporting Information Figs S1 and S2.