Chlorophyll a Biosynthetic Heterogeneity

Light and dark modulation of chlorophyll biosynthetic genes in response to temperature

“…Biosynthesis of porphyrins and particularly that of Chl during early greening stages of seedlings has been elucidated in detail (for recent reviews, see Rebeiz et al 1994;Von Wettstein et al 1995;Porra 1997;Grimm 1998;Eckhardt et al 2004). We have previously analyzed physiological responses of cucumber and wheat seedlings to chill-and heat-stress Tripathy 1998, 1999).…”

Pigment Biosynthesis: Chlorophylls, Heme, and Carotenoids

“…Variations in both chlorophyll a and chlorophyll b structure resulting from modifications introduced at different locations within the porphyrin ring or phytol tail have also been observed in some species (Rebeiz et al, 1994). It is not known at which steps during chlorophyll b biosynthesis that the observed modifications to the porphyrin ring or phytol tail take place, nor what possible functional significance these modifications may have.…”

“…It was originally thought that vinyl reduction occurred at the protochlorophyllide stage, with 3,8-divinyl protochlorophyllide being reduced to 3-monovinyl protochlorophyllide by an 8-vinyl reductase (Whyte and Griffiths, 1993). However, the results from a number of studies showed that other chlorophyll biosynthetic intermediates, including 1X, Mg-PME, and 3,8-divinyl chlorophyllide, can also serve as substrates for vinyl reduction (Richards et al, 1993;Rebeiz et al, 1994). Whether one 8-vinyl reductase with broad specificity or several 8-vinyl reductases are involved in the conversion of 3,8-divinyl tetrapyrroles to 3-monovinyl tetrapyrroles is not known.…”

“…In most plants, algae, and photosynthetic bacteria, (bacterio)chlorophyll a exists as a heterogeneous mixture of monovinyl and divinyl forms of the molecule with the final composition of the chlorophyll pool dependent upon the species, growth conditions, and stage of development (Rebeiz et al, 1994). The divinyl forms of chlorophyll a (or its biosynthetic intermediates after Mg-PME) contain vinyl groups at the 3-and 8-positions in rings A and B, respectively, whereas the monovinyl forms contain a vinyl group in the 3-position of ring A and an ethyl group at the 8-position on ring B (Fig.…”

An Overview of Chlorophylls and Bacteriochlorophylls: Biochemistry, Biophysics, Functions and Applications

“…Structural variants are found in most photosynthetic organisms, often only in small amounts, and their functions are not always known. Some have been established as biosynthetic precursors or products of (bio) degradation and include pigments esterifi ed with terpenoid alcohols other than phytol including phytadi-, tri-or tetra-ene alcohols (Schoch et al, 1977;Shioi, 1991), and also phytochlorin-pigments bearing a C-8 vinyl rather than an ethyl substituent (Rebeiz et al, 1994). However, many of these unusual Chls are functional in photosynthesis.…”