Physicochemical differences between the PR and PFR forms of phytochrome



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Texas Tech University


Light is one of the most important environmental factors that influences the life of plants. Plants utilize light energy to produce glucose through the process of photosynthesis for survival. In addition to the photosynthetic energy conversion process, plants respond developmentally to light in various ways. Phototropism and photomorphogenesis are typical examples of the response to light by plants. Phototropism is the phenomenon in which plants or plant organs bend toward light. By photomorphogenesis we refer to the light mediated changes in growth and differentiation of plants.

Phototropism and photomorphogenesis involve specific regulatory photoreceptors for the perception of light signal. Although the photoreceptor for phototropism has not yet been identified, the photoreceptor for photomorphogenesis is relatively well characterized. The most important regulatory photoreceptor involved in photomorphogenesis is phytochrome. This photoreceptor plays a central role in controlling plant growth and development during every phase of the life cycle of plants. Some examples of the control include seed germination, stem elongation, plastidogenesis, biosynthesis of chlorophylls, carotenoids and anthocyanines, flowering, dormancy and senescence.