Identification of CSU3. (A and B) CSU3 encodes PINOID protein kinase. The gene structure of CSU3 is shown. Black blocks indicate exons, and the intron is represented by a black line. The point mutation in csu3/pid-15 is shown in red. (B) The protein structure of PID and PID-15. a.a., amino acids. (C) Complementation test. The adult phenotypes of Col, cop1-6, csu3 cop1-6, csu3, PID-CFP csu3 cop1-6, and PID-GFP csu3 cop1-6 were grown under long-day (16-h light/8-h dark) conditions for 8 wk.