Special issue in honour of Prof. Reto J. Strasser - Probing the photosynthetic efficiency of some European and Anatolian Scots pine populations under UV-B radiation using polyphasic chlorophyll a fluorescence transient

Abstract

The study was carried out to examine the photosynthetic efficiency of Scot pine populations, originated from various European countries and Anatolia in Turkey, exposed to UV-B radiation. Seeds were germinated and grown in the nursery; three-year-old seedlings were exposed to UV-B for two days, eight hours per day. The photosynthetic efficiency was probed by chlorophyll a fluorescence at 24 h after UV-B treatment and analysed by JIP-test. UV-B caused reduction in quantum yields and electron transport at both donor and acceptor sides of photosystems. The performance indexes of seedlings were also negatively affected by the treatment. Populations from France, England, and three provenances of Turkey showed sensitive responses, while the populations from Spain, Romania, and Ilgaz performed their photosynthesis better. We found that UV-B affected at different levels the photosynthetic functionality of populations. Chlorophyll a fluorescence technique is very useful to identify the UV-B tolerance of different Scots pine populations, however, further studies based on molecular analyses should be applied to explain their evolutionary history.

Comparative Analysis of Primary Photosynthetic Reactions Assessed by OJIP Kinetics in Three Brassica Crops after Drought and Recovery

“…Based on our results (Figure 2a,b), it could also be used as such, especially for drought-sensitive Brassica crops. The PI total decrease in droughtstressed plants is usually associated with the downregulation of electron transport [81]. This is corroborated by the decrease in φ P0 and ψ E0, together with its quantum yield, φ E0 , in drought-stressed Chinese and white cabbage, indicating the decline in electron transport further than Q A − [37], most probably due to the induction of Q B -non-reducing RCs upon the exposure to drought [82].…”

“…The ratio of variable fluorescence at times 0.3 and 2 ms (V K /V J ) is a reliable indicator of the restrictions at the PSII donor side [81,99] and can be used as a relative measure of OEC inactivation [102]. Drought stress did not induce significant changes in V K /V J in any Brassica variety (Figure 3d).…”

“…Kale showed no changes during the treatments of any parameter. An increase in the specific fluxes ABS/RC, TR 0 /RC, and DI 0 /RC is a usual response of plants exposed to drought [33,34,37,81]. Such increase is usually the result of damaged OEC and impaired electron transport further than Q A [71,86].…”

“…After recovery, there was a significant increase in the white cabbage compared to the control, while the Chinese cabbage and kale showed no significant changes. An increase in V K /V J is usually the result of the uncoupling of OEC [81,102]. It was reported recently that UV-B radiation could induce an increase in V K /V J in sensitive and moderately tolerant populations of Scots pine seedlings [81], in rice seedlings exposed to high light, salinity, and PEG−induced drought [99], as well as in Actinidia plants deprived of nitrogen [103].…”

Environmental stress - what can we learn from chlorophyll a fluorescence analysis in woody plants? A review

“…Chlorophyll fluorescence has been successfully used in applied research to evaluate the effects of stressors on tree seedlings and small plants and to screen genotypes adapted to specific environmental conditions ( Kuhlgert et al., 2016 ; Çiçek et al., 2020 ; Dimitrova et al., 2020 ). ChlF analysis has been used by Bantis et al.…”