Photosynthetic phenotyping requires quick characterization of dynamic traits when measuring large plant numbers in a fluctuating environment. Here, we evaluated the light-induced fluorescence transient (LIFT) method for its capacity to yield rapidly fluorometric parameters from 0.6 m distance. The close approximation of LIFT to conventional chlorophyll fluorescence (ChlF) parameters is shown under controlled conditions in spinach leaves and isolated thylakoids when electron transport was impaired by anoxic conditions or chemical inhibitors. The ChlF rise from minimum fluorescence ( F o ) to maximum fluorescence induced by fast repetition rate ( F m−FRR ) flashes was dominated by reduction of the primary electron acceptor in photosystem II (Q A ). The subsequent reoxidation of Q A − was quantified using the relaxation of ChlF in 0.65 ms ( F r1 ) and 120 ms ( F r2 ) phases. Reoxidation efficiency of Q A − ( F r1 / F v , where F v = F m−FRR − F o ) decreased when electron transport was impaired, while quantum efficiency of photosystem II ( F v / F m ) showed often no significant effect. ChlF relaxations of the LIFT were similar to an independent other method. Under increasing light intensities, F r2 ′/ F q ′ (where F r2 ′ and F q ′ represent F r2 and F v in the light-adapted state, respectively) was hardly affected, whereas the operating efficiency of photosystem II ( F q ′/ F m ′) decreased due to non-photochemical quenching. F m−FRR was significantly lower than the ChlF maximum induced by multiple turnover ( F m−MT ) flashes. However, the resulting F v / F m and F q ′/ F m ′ from both flashes were highly correlated. The LIFT method complements F v / F m with information about efficiency of electron transport. Measurements in situ and from a distance facilitate application in high-throughput and automated phenotyping. Electronic supplementary material The online version of this article (10.1007/s11120-018-0594-9) contains supplementary m...

The adaptive response of Sorghum bicolor landraces from Egypt to drought stress and following recovery was analyzed using two-dimensional difference gel electrophoresis, 2D-DIGE. Physiological measurements and proteome alterations of accession number 11434, drought tolerant, and accession number 11431, drought sensitive, were compared to their relative control values after drought stress and following recovery. Differentially expressed proteins were analysed by Matrix assisted laser desorption ionisation time-of-flight mass spectrometry, MALDI-TOF-MS. Alterations in protein contents related to the energy balance, metabolism (sensu Mewes et al. 1997), and chaperons were the most apparent features to elucidate the differences between the drought tolerant and sensitive accessions. Further alterations in the levels of proteins related to transcription and protein synthesis are discussed.

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The impact of (long-term) drought acclimation and (short-term) heat stress and their combination on fast chlorophyll fluorescence induction curves (OJIP) and grain yield was tested using pot-grown plants of wild barley (Hordeum spontaneum) originating from Northern Egypt. Concerning agronomic traits, the main effect of drought was decreased biomass accumulation and grain yield, while heat specifically affected floral development. The treatments caused specific inhibitions of photosystem II (PSII) functionality. While heat stressed plants showed a reduction of maximum quantum efficiency of PSII (φP0), an indication of effects on oxygen evolving complex (OEC) functionality, and the connectivity of PSII units, these features were entirely missing in drought acclimated plants. Drought caused a reduction of the Performance Index (PIabs) and of the relative amplitude of the IP-phase of the OJIP induction curve (ΔVIP). Individuals suffering from a combination of drought and heat showed a better ability to recover photosynthetic electron transport after the relief of stress in comparison to heat stressed plants. However, this improved capacity to recover was not accompanied by an increased grain yield. Thus, we conclude that chlorophyll fluorescence measurements provide valuable physiological data; however, their use in agronomic studies for the prediction of agronomic traits should be done with some precaution.