Recent Advances in the Role of Light Quality and Phytochrome in Plant Defense Resistance Against Environmental Stresses Timing of Photoperiodic Flowering: Light Perception and Circadian Clock Recent Advances in the Role of Light Quality and Phytochrome in Plant Defense Resistance Against Environmental Stresses Advances of Mechanism of Nuclear Accumulation in Plant Phytochromes The Role of Phytochrome in Stress Tolerance