ABSTRACT
A host of environmental factors is involved in the regulation of metabolite biosynthesis in plants. The need for this control of synthesis stems from the fact that plants must be able to adjust the production of metabolites according to changing factors if they are to survive. Light is obviously a key factor in the ultimate production of many compounds, because it supplies the energy needed to fix carbon. It is also more directly necessary for the biosynthesis of compounds, such as chlorophylls, as mentioned in Chapter 2. Here, photons trigger the enzymatic conversion of protochlorophyllide and phytol to chlorophylls
a
and
b
and, hence, to chlorophyll-protein complexes in chloroplasts (Mohr and Schopfer, 1995). Light also catalyzes the synthesis of anthocyanin pigment, via the plant pigment
phytochrome
, in many tissues of many plants, such as cotyledon (seed leaf) epidermal cells and hypocotyl (stem portion below the cotyledons) subepidermal cells in mustard seedlings (Mohr and Schopfer, 1995).
