Cyclic electron flow in hpr1 mutants. Cyclic electron flow in hpr1 mutants. The plot shows vH+ versus LEF (measured by chlorophyll fluorescence quenching analysis). The error bars indicate sd. The linear regressions were y = 0.0037x − 0.025, R2 = 0.9997 for Col-0 (white squares/black line), y = 0.0053x – 0.0064, R2 = 0.995 for hpr1-1 (upward triangles, light gray line), and y = 0.0063x – 0.065, R2 = 0.97 for hpr1-2 (downward triangles, dark gray line). Jiying Li et al. Plant Physiol. 2019;180:783-792 ©2019 by American Society of Plant Biologists