The photoreceptor interaction network.

CASAL, JORGE J.

Photomorphogenesis in Plants and Bacteria: Function and Signal Transduction Mechanisms.

Kluwer Academic Pub

Año: 2006; p. 407 - 437

Plants are exposed to stressful conditions including the aggressive transition between belowground and aboveground environments, the presence of competitors, and seasons with extreme temperatures or shortage of water. Specific combinations of irradiance, spectral composition, duration of the daily photoperiod and angle of incidence of light are tightly linked to these threats and very often anticipate their impending occurrence (Figure 1). When an organ emerges from the soil, it experiences a transition between full darkness and daily light cycles. The ratio between red light and far-red light (R:FR) is inversely related to the presence, size and position of neighbour plants that can compete for resources, because green leaves reflect and transmit much more far-red than red light (see Chapter 22). The photoperiod correlates with time of the year. The angle of incidence depends on the position of neighbours and soil aggregates or stones. The perception and transduction of these signals by the network formed by phytochromes, cryptochromes, phototropins and their downstream signalling elements leads to changes in plant growth and development that favour adjustment to the associated stressful conditions.