Chlorophyll a fluorescence as a tool to monitor physiological status of plants under abiotic stress conditions (original) (raw)
Related papers
2015
Analyzing the changes that occur in the photosynthetic machinery of plants is one of the most informative approaches for evaluation of the plant physiological state, their stress reactions, productivity and the adaptive mechanisms that develop in order to protect the plant in a changing environment. An informative method for detection and analyzing of the photosynthetic process is measuring the chlorophyll a fluorescence emitted from leaves. Illumination of a plant sample induces a rise in the chlorophyll a fluorescence that draws characteristic induction curves which carry broad spectrum of data about every step of the photosynthetic process. Chlorophyll a fluorescence gives two types of signals – prompt (PF) and delayed chlorophyll fluorescence (DF). The Multifunctional Plant Efficiency Analyzer (MPEA), developed by Hansatech is constructed to measure both simultaneously in only one measurement, but as the initial steps of their kinetics overlap they cannot be recorded together wh...
Photosynthetica, 2005
A flash-lamp chlorophyll (Chl) fluorescence imaging system (FL-FIS) is described that allows to screen and image the photosynthetic activity of several thousand leaf points (pixels) of intact leaves in a non-destructive way within a few seconds. This includes also the registration of several thousand leaf point images of the four natural fluorescence bands of plants in the blue (440 nm) and green (520 nm) regions as well as the red (near 690 nm) and far-red (near 740 nm) Chl fluorescence. The latest components of this Karlsruhe FL-FIS are presented as well as its advantage as compared to the classical single leaf point measurements where only the fluorescence information of one leaf point is sensed per each measurement. Moreover, using the conventional He-Ne-laser induced two-wavelengths Chl fluorometer LITWaF, we demonstrated that the photosynthetic activity of leaves can be determined measuring the Chl fluorescence decrease ratio, R Fd (defined as Chl fluorescence decrease F d from maximum to steady state fluorescence F s : F d /F s), that is determined by the Chl fluorescence induction kinetics (Kautsky effect). The height of the values of the Chl fluorescence decrease ratio R Fd is linearly correlated to the net photosynthetic CO 2 fixation rate P N as is indicated here for sun and shade leaves of various trees that considerably differ in their P N. Imaging the R Fd-ratio of intact leaves permitted the detection of considerable gradients in photosynthetic capacity across the leaf area as well as the spatial heterogeneity and patchiness of photosynthetic quantum conversion within the control leaf and the stressed plants. The higher photosynthetic capacity of sun versus shade leaves was screened by Chl fluorescence imaging. Profile analysis of fluoresence signals (along a line across the leaf area) and histograms (the signal frequency distribution of the fluorescence information of all measured leaf pixels) of Chl fluorescence yield and Chl fluorescence ratios allow, with a high statistical significance, the quantification of the differences in photosynthetic activity between various areas of the leaf as well as between control leaves and water stressed leaves. The progressive uptake and transfer of the herbicide diuron via the petiole into the leaf of an intact plant and the concomitant loss of photosynthetic quantum conversion was followed with high precision by imaging the increase of the red Chl fluorescence F 690. Differences in the availability and absorption of soil nitrogen of crop plants can be documented via this flash-lamp fluorescence imaging technique by imaging the blue/red ratio image F 440 /F 690 , whereas differences in Chl content are detected by collecting images of the fluorescence ratio red/far-red, F 690 /F 740 .
Phenotyping Plant Responses to Biotic Stress by Chlorophyll Fluorescence Imaging
Frontiers in Plant Science
Photosynthesis is a pivotal process in plant physiology, and its regulation plays an important role in plant defense against biotic stress. Interactions with pathogens and pests often cause alterations in the metabolism of sugars and sink/source relationships. These changes can be part of the plant defense mechanisms to limit nutrient availability to the pathogens. In other cases, these alterations can be the result of pests manipulating the plant metabolism for their own benefit. The effects of biotic stress on plant physiology are typically heterogeneous, both spatially and temporarily. Chlorophyll fluorescence imaging is a powerful tool to mine the activity of photosynthesis at cellular, leaf, and whole-plant scale, allowing the phenotyping of plants. This review will recapitulate the responses of the photosynthetic machinery to biotic stress factors, from pathogens (viruses, bacteria, and fungi) to pests (herbivory) analyzed by chlorophyll fluorescence imaging both at the lab and field scale. Moreover, chlorophyll fluorescence imagers and alternative techniques to indirectly evaluate photosynthetic traits used at field scale are also revised.
Plant and Cell Physiology, 2000
Parallel measurements of CO 2 assimilation, Chi fluorescence and 800 nm transmittance were carried out on intact leaves of wild type and cytochrome b 6 /f deficient transgenic tobacco grown at two different light intensities and temperatures, with the aim to diagnose processes limiting quantum yield of photosynthesis and investigate their adaptations to growth conditions. Relative optical crosssections of PSII and PSI antennae were calculated from measured gas exchange rates and fluorescence-related losses at PSII and P700 oxidation-related losses at PSI. In nonstress conditions (high light grown wild type and low light grown antisense type) optimal relative optical cross-section of PSII (fl n) was 0.48-0.51 and that of PSI («i) was 0.38-0.40, leaving a non-photosynthetic absorption cross-section (a 0) of 0.09-0.14 for nitrite assimilation and absorption in PSII/? and other photosynthetically inactive pigments. Stress conditions (low light grown wild type and high light grown antisense type, elevated growth temperatures) tend to increase a 0 and decrease PSII antenna crosssection more than that of PSI antenna, but this rule is reversed during senescence.
Biochimica et Biophysica Acta (BBA) - Bioenergetics, 2002
Green leaves illuminated with photosynthetically active light emit red fluorescence, whose time-dependent intensity variations reflect photosynthetic electron transport (the Kautsky effect). Usually, fluorescence variations are discussed by considering only the contribution of PSII-associated chlorophyll a, although it is known that the fluorescence of PSI-associated chlorophyll a also contributes to the total fluorescence [Aust. J. Plant Physiol. 22 (1995) 131]. Because the fluorescence emitted by each photosystem cannot be measured separately by selecting the emission wavelength in in vivo conditions, the contribution of PSI to total fluorescence at room temperature is still in ambiguity. By using a diode array detector, we measured fluorescence emission spectra corresponding to the minimal (F O) and maximal (F M) fluorescence states. We showed that the different shapes of these spectra were mainly due to a higher contribution of PSI chlorophylls in the F O spectrum. By exciting PSI preferentially, we recorded a reference PSI emission spectrum in the near far-red region. From the F O and F M spectra and from this PSI reference spectrum, we derived specific PSI and PSII emission spectra in both the F O and F M states. This enables to estimate true value of the relative variable fluorescence of PSII, which was underestimated in previous works. Accurate separation of PSI-PSII fluorescence emission spectra will also enable further investigations of the distribution of excitation energy between PSI and PSII under in vivo conditions.
Annali di Botanica, 2016
Chlorophyll (Chl) a fluorescence is a widely used tool to monitor the photosynthetic process in plants subjected to environmental stresses. this review reports the theoretical bases of Chl fluorescence, and the significance of the most important Chl fluorescence parameters. it also reports how these parameters can be utilised to estimate changes in photosystem (Ps) ii photochemistry, linear electron flux and dissipation mechanisms. the relation between actual Psii photochemistry and Co 2 assimilation is discussed, as is the role of photochemical and non-photochemical quenching in inducing changes in Psii activity. the application of Chl fluorescence imaging to study heterogeneity on leaf lamina is also considered. this review summarises only some of the results obtained by this methodology to study the effects of different environmental stresses, namely water availability, nutrients, pollutants, temperature and salinity.