Plant Materials and Growth Conditions

The Arabidopsis (Arabidopsis thaliana) Columbia-0 ecotype was used as the wild type. The following T-DNA insertion lines were described previously: pat10-1 (Zhou et al., 2013), cbl2 (Tang et al., 2012), cbl3 (Tang et al., 2012), cipk9-1 (Pandey et al., 2007), and tpk1-1 (Gobert et al., 2007). The mutant for CIPK17, cipk17 (SALK_062790), was obtained from the ABRC (http://abrc.osu.edu). Arabidopsis plant growth and transformation were as described (Zhou et al., 2013). For drought treatment, plants at 20 DAG were withheld water for 20 d. Chlorophyll (a + b) were extracted from the fourth pair of rosette leaves from plants that were not watered for 15 d. Rewatering was performed as described (Nelson et al., 2007). Measurement was performed as described (Zhao et al., 2016). Histochemical GUS staining was performed as described (Zhou et al., 2013).