Chlorophyll a fluorescence and photosystem activities in the trangenics
Chl a fluorescence has been used as a non-invasive signature of photosynthesis, particularly of PSII (Krause and Weis, 1991; Strasser and Srivastava, 1995; Papageorgiou and Govindjee (eds), 2004; Baker, 2008; Stirbet et al., 2018). When a dark-adapted photosynthetic organism is exposed to blue light (λ- 460 mm), Chl a fluorescence rises from a low initial minimum level (F o) to a high level (F m) (Munday and Govindjee, 1969a; Munday and Govindjee, 1969b). The CA over-expressers had higherF o (Table 2 ) partly due to higher Chl content. However, there could be several other reasons to have higherF o in the transgenics, e.g., higher concentration of QB- in dark-adapted samples (Schreiber and Armond, 1978; Cao and Govindjee, 1990; Yamane et al., 1997). However, the maximum primary photochemical efficiency of PSII, as inferred fromF v/F m in dark-adapted leaves, was ~5% higher in the transgenic plants demonstrating higher efficiency of PSII (Genty et al., 1992; Baker et al., 2007).