Fig. 6: A working model of CBL1/9-CIPK1-PYLs module regulating plant drought stress responses. | Nature Communications

Fig. 6: A working model of CBL1/9-CIPK1-PYLs module regulating plant drought stress responses.

From: The CBL1/9-CIPK1 calcium sensor negatively regulates drought stress by phosphorylating the PYLs ABA receptor

Fig. 6

A proposed model illustrating how the phosphorylation of ABA receptors by CIPK1 acts as a negative regulator of drought stress responses in plants. Under normal conditions, CIPK1 acts to suppress the activation of ABA responses by phosphorylating PYL4 at Ser129, which inactivates the ABA receptor and prevents it from inhibiting the phosphatase activities of ABI1/PP2Cs. This results in a lack of downstream ABA signaling. However, under drought stress conditions, ABA inhibits CBL1/9-CIPK1-mediated phosphorylation of PYR1/PYL1-6, and active ABA receptors interact with ABI1/PP2Cs to inhibit their phosphatase activity, leading to the activation of downstream ABA signaling. This response enables plants to survive under drought stress. Positive regulation is indicated by arrows with solid lines, while strong negative regulation is represented by a solid line with a horizontal bar.

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