Light signals, phytochromes and cross-talk with other environmental cues

Plants have evolved highly complex sensory mechan-isms to monitor their surroundings and adapt their growth and development to the prevailing environ-mental conditions. The integration of information from multiple environmental cues enables the co-ordination of development with favourable seasonal conditions and, ultimately, determines plant form. Light signals, perceived via the phytochrome, crypto-chrome and phototropin photoreceptor families, are especially important environmental signals. Redundancy of function among phytochromes and their interaction with blue light photoreceptors enhance sensitivity to light signals, facilitating the accurate detection of, and response to, environmen-tal ¯uctuations. In this review, current understanding of Arabidopsis phytochrome functions will be sum-marized, in particular, the interactions among the phytochromes and the integration of light signals with directional and temperature sensing mechan-isms. Key words: Arabidopsis, environmental cues, light signals, photoreceptors, temperature sensing mechanisms