The Chl b Biosynthetic Pathway:Intermediary Metabolism - Chlorophyll Biosynthesis and Technological Applications - page 300

Fig. 13.16 Biosynthesis of MV Chl b via routes 12 and 14 in greening DMV-LDV-LDMV plants
during the light phases of the photoperiod (Adapted from Fig. 6.4 of Chap. 6 )
MV Chl b accumulation, monitored by sensitive fluorescence techniques
(Rebeiz 2002 ) is observed after 15-30 min of dark-incubation. We propose that
the biosynthesis of this MV Chl b originates in routes 12 and 14.
In route 12, MV Chl b would be formed from MV Chl a which is formed in turn
from MV Pchlide a and MV Chlide a (Fig. 13.16 ). Under the same conditions,
conversion of MV Chl a to MV Chl b by route 12 appeared to be low, and amounted
to a maximum of 5 % after 7 h of greening (Rebeiz et al. 1999 ). These results
indicated that under these conditions, the fate of the nascent MV Chlide a was
conversion to MV Chl b by way of MV Chlide b rather than conversion to MV Chl
b via MV Chl a . After 7 h of greening, the rate of MV Chl b formation from MV
Chlide a and b increased to 56-68 % (Rebeiz et al. 1999 ).
Since during the initial phases of greening of etiolated tissues, most of the Chl
consists of MV Chl, located in PSI and PSII (Akoyunoglou 1978 ; Akoyunoglou
et al. 1981 ; Alberte et al. 1972 ), we propose that the MV Chl b formed via routes