Typesetter to place Table 2 here
Fo : The F o was
measured in dark adapted leaves as the initial minimum fluorescence. As
compared to the VC, CAx3 and CAx5 plants had ~8% and
~11% higher F o values, but this
must be simply due to higher [Chl] in the transgenics (Table
2); there was no difference in the values ofF o/Chl.
Fm : Maximal fluorescence was measured
during the first saturation pulse, after dark adaptation (see Material
and Methods). The F m values of CAx3 and CAx5
plants are observed to be higher by ~18% and
~25% (Table 2); theF m/Chl values are 6%-9% higher in the
transgenics than in the VC.
Fv /Fm : This
ratio is an estimate of the maximum potential quantum efficiency of
Photosystem II, if all the reaction centers are open.; this is usually
the case when dark-adapted samples are used, as was the case in our
experiments; this ratio increased only slightly (~4%)
in the transgenic plants (Table 2).
Area over the OJIP curve: This area is betweenF o and F m, and is
proportional to the size of the pool of the electron acceptors in PSII,
mainly the plastoquinone molecules (Malkin and Kok, 1966); we observe it
to be higher (19%-22%) in CAx3 and CAx5 than in the VC (Table
2).
Fv/ Fo: This
ratio, which is known to reflect the efficiency of the (electron) donor
side of PSII, i.e., the activity of the oxygen-evolving (or the
water-splitting) complex (Burke, 1990), was higher (11%- 16%) in the
transgenics than in the VC (Table 2).
PI, the performance index: The calculated PI
(Tsimilli-Michael et al., 2000) was higher (10%- 20%) in the
transgenics than in the VC (Table 2).
Non Photochemical quenching (NPQ): NPQ of the excited state of
Chl increased with light intensity. At high light intensity (540 μmol
photons m-2 s-1), the NPQ in CAx3
and CAx5 transgenic lines is slightly lower (5% - 9%) than in the VC