Light Sensing at the Plasma Membrane

Abstract

Light is one of the most important environmental factors controlling plant development and its perception is achieved through a suite of photoreceptor proteins. Like photoreceptors associated with our vision, plant photosensors can detect the presence, intensity, direction and color of light, and in turn, utilize this information to direct their growth accordingly. To date, four different types of photoreceptors have been identified in plants, namely the phytochromes, cryptochromes, phototropins and members of the Zeitlupe (ZTL) family. Phytochromes are photoreversible red/far-red photoreceptors whereas cryptochromes, phototropins and members of the ZTL family specifically absorb UV-A/blue wavelengths. Plants also respond to UV-B and green light, but the photosensors responsible for their detection remain elusive. A summary of light-regulated events that are known to occur at the plant plasma membrane will be discussed, as will the biochemical and photochemical properties of the photoreceptor proteins involved.

Two Distinct Molecular Types of Phytochrome A in Plants: Evidence of Existence and Implications for Functioning

“…The integration between the phytochrome A and phototropin regulatory pathways involves Phytochrome Kinase Substrate 1 (PKS1)-a protein associated with the plasma membrane, which interact with both PHYA and PHOT1 [179,180]. The effects of phytochrome on hypocotyl growth [176] involve an integral membrane-bound protein associated with auxin transport [181] (see review [182]). The control of translation of PORA mRNA is also mediated by cytoplasmic phyA: phyA in the active Pfr state binds to PENTA 1 (PNT1) and represses the translation of mRNAs [28,29].…”