CsFtsH5’s interaction with CsCIPK11. (a) The expression patterns of CsCIPK11 in tea plant tissues, including bud, 1st L, 2nd L, 3rd L, mature L, stem, flower, seed, and root. Samples were collected on April 2020 and October 2020. (b) The CsCIPK11 expression in tea plants under 22 °C and 4 °C treatments for 1, 3, 6, and 12 h, as well as 1, 2, and 3 d. Data are shown as the mean ± SEM (n = 3). Asterisks indicate significant differences according to t-tests (** p < 0.01). (c) The expression patterns of CsCIPK11 in leaves of ZC604 cultivar and ZH1 cultivar under 100% and 10% sunlight conditions. Means of three replicates and standard errors are presented; different letters above the column indicate significant difference at p < 0.05 using LSD’s test. Values in (a,c) are expressed relative to the expression levels of reference gene using formula 2−ΔCt. Values in (b) are expressed relative to the expression levels of 22 °C group using formula 2−ΔΔCt. CsPTB was used as a reference gene in expression analysis. (d) Y2H assay of pGBKT7-CsCIPK11 and pGADT7-CsFtsH5 in AH109 strain. DDO, SD/−Leu/−Trp; QDO, SD/−Leu/−Trp/−His/−Ade; X, X-α-gal. pGBKT7-53 and pGADT7-T acted as the positive control, while pGBKT7-lam and pGADT7-T served as the negative control. (e) Luciferase complementation imaging analysis of CsCIPK11-nLuc and CsFtsH5-cLuc in Nicotiana benthamiana leaves. CsCIPK11-nLuc with cLuc, nLuc with CsFtsH5-cLuc, and nLuc with cLuc served as controls.