Functions Of Arabidopsis Development : Plant Stems Grow Towards Bright Lateral Light
4962 Words Feb 22nd, 2016 20 Pages
Plant stems grow towards bright lateral light. This is known to involve three main families of transducing photoreceptors the red and far red light absorbing phytochromes and the UV-A/ blue light absorbing cytochromes and the phototropism. The phytochrome family are reversible photocrhomatic biliproteins. These exists as dimers with each monomer comprising an apoprotein covalently attached to a light absorbing linear tetrapyyrrole chromophore and phytochrombolin. Phytochromes are syntheisized in the dark in its inactive Absorbing Pr form. Biological activity is acquired upon photo conversion to the far red ligh absorbing Pfr form in a reaction optimized at red wavelengths. Photo conversion of Pfr back to the inactive Pr form is optimized at Fr wavelengths leading to an equilibrium in Pfr and PR forms.
Plants contains many different types of phytochromes which are present in angiosperms. Phytchromes have been identified in dicotyledonous which represent the products of recent gene duplications. In Arabidopsis five genes encoding phytochrome apoprotiens have been identified and sequenced. Such as the PHY B showing the greatest similarity to PHYD about 80% and forms an evolutionary subgroup with PHYE relate to PHYC the phyA photoreceptor displays unique properties in contrast to other phytochromes. PHYA displays rapid lability in the Pfr form and can signal between photo conversion between Pr and Pfr PHY A is the predominant…