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a
biosynthetic route or the results of a sluggish DV Pchlide
a
biosynthetic route
coupled to an active MV Pchlide
a
biosynthetic route coupled to a rapid photocon-
version of the nascent MV Pchlide
a
to MV Chlide
a
. This issue was investigated as
described below.
14.3.1 The Dark-Monovinyl/Light-Divinyl/Light-Dark
Monovinyl/Greening Group of Plants
In order to determine whether the Pchlide
a
detected in the light was the manifesta-
tion of an overly active DV Pchlide
a
biosynthetic route or the results of a sluggish
DV Pchlide
a
biosynthetic route coupled to an active MV Pchlide
a
biosynthetic
route and a rapid photoconversion of the nascent MV Pchlide
a
to MV Chlide
a
, the
following experimental strategy was devised.
Corn seedlings that exhibited DV Pchlide
a
accumulation in the light, were
transferred to darkness for various periods of time after 8 h of light during the light
phase of the photoperiod, and the MV and DV Pchlide
a
content of the Pchlide
a
pool were determined immediately after transfer to darkness and after various
period of time in darkness.
As shown in Fig.
14.1
, immediately after transfer to darkness, the rate of MV
Pchlide
a
started to increase sharply while the content of DV Pchlide
a
content
decreased significantly indicating a sluggish DV Pchlide
a
biosynthetic route.
Consequently this greening group of plants was called a Dark Monovinyl/Light-
Divinyl/Light-dark Monovinyl/Greening group.
14.3.2 The Dark-Divinyl/Light-Divinyl/Light-Dark
Divinyl Greening Group of Plants
The functional Pchlide
a
biosynthetic route was investigated in the same manner in
Dark Divinyl-Light Divinyl plants. After 8 h into the light phase of the photoperiod,
cucumber seedlings were moved to darkness and the DV and MV Pchlide
a
content
of the green cotyledons was investigated after various times in darkness.
As shown in Fig.
14.2
, the rate of DV Pchlide
a
biosynthesis increased sharply while
the rate ofMVPchlide formation dropped continuously. This in turn strongly suggested
that in these plants the functional Pchlide
a
biosynthetic route was a DV route.
This greening group of plants was designated as a Dark Divinyl/Light-Divinyl/
Light-dark Divinyl/Greening group.
14.3.3 The Dark Monovinyl/Light-Monovinyl/Light-Dark
Monovinyl Greening Group of Plants
DMV-LMV monocotyledonous plants such as johnsongrass differ from monocoty-
ledonous DMV-LDV plants such as oat and barley by the amounts of DV and MV
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