Structural and functional disorder in the photosynthetic apparatus of radish plants under magnesium deficiency

2018 ◽  
Vol 45 (6) ◽  
pp. 668 ◽  
Author(s):  
Izabela A. Samborska ◽  
Hazem M. Kalaji ◽  
Leszek Sieczko ◽  
Vasilij Goltsev ◽  
Wojciech Borucki ◽  
...  
Keyword(s):  
Magnesium Deficiency ◽  
Photosynthetic Apparatus ◽  
Dissipated Energy ◽  
Reaction Centre ◽  
Variable Fluorescence ◽  
Mg Deficiency ◽  
Chl A ◽  
Chl A Fluorescence ◽  
Relative Variable ◽  
Relative Variable Fluorescence

Magnesium (Mg) is one of the significant macronutrients which is involved in the structural stabilisation of plant tissues and many enzymes such as PSII. The latter efficiency and performance were analysed, using chlorophyll (Chl) a fluorescence induction kinetics and microscopic images, to detect the changes in structure and function of photosynthetic apparatus of radish plants grown under Mg deficiency (Mgdef). Plants grown under Mgdef showed less PSII connectivity and fewer active primary electron acceptors (QA) oxidizing reaction centres than control plants. Confocal and electron microscopy analyses showed an increased amount of starch in chloroplasts, and 3,3ʹ-diaminobenzidine (DAB)-uptake method revealed higher H2O2 accumulation under Mgdef. Prominent changes in the Chl a fluorescence parameters such as dissipated energy flux per reaction centre (DIo/RC), relative variable fluorescence at 150 μs (Vl), and the sum of the partial driving forces for the events involved in OJIP fluorescence rise (DFabs) were observed under Mg deficiency. The latter also significantly affected some other parameters such as dissipated energy fluxes per cross-section (DIo/CSo), performance index for energy conservation from photons absorbed by PSII antenna until the reduction of PSI acceptors (PItotal), and relative variable fluorescence at 300 μs (Vk). This work emphasises the use of chlorophyll fluorescence in combination with microscopic and statistical analyses to diagnose the effects of nutrients deficiency stress on plants at an early stage of its development as demonstrated for the example of Mgdef. Due to the short growth period and simple cultivation conditions of radish plant we recommend it as a new standard (model) plant to study nutrients deficiency and changes in plant photosynthetic efficiency under stress conditions.

scholarly journals Leaf Gas Exchange and Chlorophyll a Fluorescence Imaging of Rice Leaves Infected with Monographella albescens

2015 ◽  
Vol 105 (2) ◽  
pp. 180-188 ◽  
Author(s):  
Sandro Dan Tatagiba ◽  
Fábio Murilo DaMatta ◽  
Fabrício Ávila Rodrigues
Keyword(s):  
Gas Exchange ◽  
Fluorescence Imaging ◽  
Leaf Gas Exchange ◽  
Photosynthetic Pigment ◽  
Photochemical Efficiency ◽  
Photosynthetic Apparatus ◽  
Photochemical Quenching ◽  
Chl A ◽  
Chl A Fluorescence ◽  
Rice Leaves

This study was intended to analyze the photosynthetic performance of rice leaf blades infected with Monographella albescens by combining chlorophyll (Chl) a fluorescence images with gas exchange and photosynthetic pigment pools. The net CO2 assimilation rate, stomatal conductance, transpiration rate, total Chl and carotenoid pools, and Chl a/b ratio all decreased but the internal CO2 concentration increased in the inoculated plants compared with their noninoculated counterparts. The first detectable changes in the images of Chl a fluorescence from the leaves of inoculated plants were already evident at 24 h after inoculation (hai) and increased dramatically as the leaf scald lesions expanded. However, these changes were negligible for the photosystem II photochemical efficiency (Fv/Fm) at 24 hai, in contrast to other Chl fluorescence traits such as the photochemical quenching coefficient, yield of photochemistry, and yield for dissipation by downregulation; which, therefore, were much more sensitive than the Fv/Fm ratio in assessing the early stages of fungal infection. It was also demonstrated that M. albescens was able to impair the photosynthetic process in both symptomatic and asymptomatic leaf areas. Overall, it was proven that Chl a fluorescence imaging is an excellent tool to describe the loss of functionality of the photosynthetic apparatus occurring in rice leaves upon infection by M. albescens.

scholarly journals Ascorbic Acid-Induced Photosynthetic Adaptability of Processing Tomatoes to Salt Stress Probed by Fast OJIP Fluorescence Rise

2021 ◽  
Vol 12 ◽  
Author(s):  
Xianjun Chen ◽  
Yan Zhou ◽  
Yundan Cong ◽  
Pusheng Zhu ◽  
Jiayi Xing ◽  
...  
Keyword(s):  
Ascorbic Acid ◽  
Salt Stress ◽  
Excitation Energy ◽  
Fluorescence Intensity ◽  
Heat Dissipation ◽  
Variable Fluorescence ◽  
Fluorescence Rise ◽  
Relative Variable ◽  
Relative Variable Fluorescence ◽  
Processing Tomatoes

In this study, the protective role of exogenous ascorbic acid (AsA) on salt-induced inhibition of photosynthesis in the seedlings of processing tomatoes under salt stress has been investigated. Plants under salt stress (NaCl, 100 mmol/L) were foliar-sprayed with AsA (0.5 mmol/L), lycorine (LYC, 0.25 mmol/L, an inhibitor of key AsA synthesis enzyme l-galactono-γ-lactone dehydrogenase activity), or AsA plus LYC. The effects of AsA on fast OJIP fluorescence rise curve and JIP parameters were then examined. Our results demonstrated that applying exogenous AsA significantly changed the composition of O-J-I-P fluorescence transients in plants subjected to salt stress both with and without LYC. An increase in basal fluorescence (Fo) and a decrease in maximum fluorescence (Fm) were observed. Lower K- and L-bands and higher I-band were detected on the OJIP transient curves compared, respectively, with salt-stressed plants with and without LYC. AsA application also significantly increased the values of normalized total complementary area (Sm), relative variable fluorescence intensity at the I-step (VI), absorbed light energy (ABS/CSm), excitation energy (TRo/CSm), and reduction energy entering the electron transfer chain beyond QA (ETo/CSm) per reaction centre (RC) and electron transport flux per active RC (ETo/RC), while decreasing some others like the approximated initial slope of the fluorescence transient (Mo), relative variable fluorescence intensity at the K-step (VK), average absorption (ABS/RC), trapping (TRo/RC), heat dissipation (DIo/RC) per active RC, and heat dissipation per active RC (DIo/CSm) in the presence or absence of LYC. These results suggested that exogenous AsA counteracted salt-induced photoinhibition mainly by modulating the endogenous AsA level and redox state in the chloroplast to promote chlorophyll synthesis and alleviate the damage of oxidative stress to photosynthetic apparatus. AsA can also raise the efficiency of light utilization as well as excitation energy dissipation within the photosystem II (PSII) antennae, thus increasing the stability of PSII and promoting the movement of electrons among PS1 and PSII in tomato seedling leaves subjected to salt stress.

scholarly journals The effect of storage temperature of cucumber fruit on chlorophyll fluorescence

2013 ◽  
Vol 53 (1) ◽  
pp. 57-64
Author(s):  
Ryszard Kosson
Keyword(s):  
Chlorophyll Fluorescence ◽  
Storage Temperature ◽  
Optimum Level ◽  
Variable Fluorescence ◽  
Fluorescence Measurements ◽  
Cucumber Fruit ◽  
Variable Chlorophyll Fluorescence ◽  
Relative Variable ◽  
Temperature Levels ◽  
Relative Variable Fluorescence

The effect of three storage temperature levels: 12,5°C, 20°C, and 1,5°C on basic indexes of chlorophyll fluorescence of cucumber fruits was studied. The greenhouse grown cucumber fruits cv. Wiktor F1 were stored in perforated polyethylene bags or without packages. The minimum chlorophyll fluorescence (Fo), maximum chlorophyll fluorescence (Fm), variable chlorophyll fluorescence (Fv) and relative variable fluorescence (Fv/Fm) of the cucumber peel were measured. Relative variable fluorescence was decTeasing when cucumbers were stored at temperature lower or higher than optimum level. The chlorophyll fluorescence measurements can be helpful for determination of appropriate temperature parameters of cucumber storage.

A Poisson-Pareto model of Chl-a fluorescence signals in marine environments

2015 ◽  
Vol 55 ◽  
pp. 373
Author(s):  
Stephen Woodcock ◽  
Bojana Manojlovic ◽  
Mark Baird ◽  
Peter Ralph
Keyword(s):  
Marine Environments ◽  
Chl A ◽  
Chl A Fluorescence ◽  
Pareto Model

Non-photochemical quenching of chlorophyll a fluorescence: early history and characterization of two xanthophyll-cycle mutants of Chlamydomonas reinhardtii

2002 ◽  
Vol 29 (10) ◽  
pp. 1141 ◽  
Author(s):  
Govindjee ◽  
Manfredo J. Seufferheld
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Oxygen Evolution ◽  
Xanthophyll Cycle ◽  
Photochemical Quenching ◽  
Chl A ◽  
Fluorescence Transient ◽  
Chl A Fluorescence ◽  
Non Photochemical Quenching

This paper deals first with the early, although incomplete, history of photoinhibition, of 'non-QA-related chlorophyll (Chl) a fluorescence changes', and the xanthophyll cycle that preceded the discovery of the correlation between non-photochemical quenching of Chl a fluorescence (NPQ) and conversion of violaxanthin to zeaxanthin. It includes the crucial observation that the fluorescence intensity quenching, when plants are exposed to excess light, is indeed due to a change in the quantum yield of fluorescence. The history ends with a novel turn in the direction of research — isolation and characterization of NPQ xanthophyll-cycle mutants of Chlamydomonas reinhardtii Dangeard and Arabidopsis thaliana (L.) Heynh., blocked in conversion of violaxanthin to zeaxanthin, and zeaxanthin to violaxanthin, respectively. In the second part of the paper, we extend the characterization of two of these mutants (npq1, which accumulates violaxanthin, and npq2, which accumulates zeaxanthin) through parallel measurements on growth, and several assays of PSII function: oxygen evolution, Chl a fluorescence transient (the Kautsky effect), the two-electron gate function of PSII, the back reactions around PSII, and measurements of NPQ by pulse-amplitude modulation (PAM 2000) fluorimeter. We show that, in the npq2 mutant, Chl a fluorescence is quenched both in the absence and presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU). However, no differences are observed in functioning of the electron-acceptor side of PSII — both the two-electron gate and the back reactions are unchanged. In addition, the role of protons in fluorescence quenching during the 'P-to-S' fluorescence transient was confirmed by the effect of nigericin in decreasing this quenching effect. Also, the absence of zeaxanthin in the npq1 mutant leads to reduced oxygen evolution at high light intensity, suggesting another protective role of this carotenoid. The available data not only support the current model of NPQ that includes roles for both pH and the xanthophylls, but also are consistent with additional protective roles of zeaxanthin. However, this paper emphasizes that we still lack sufficient understanding of the different parts of NPQ, and that the precise mechanisms of photoprotection in the alga Chlamydomonas may not be the same as those in higher plants.

scholarly journals On the origin of the increased tissue iron content in graded magnesium deficiency states in the rat

1997 ◽  
Vol 77 (3) ◽  
pp. 475-490 ◽  
Author(s):  
Klaus Schumann ◽  
Annette Lebeau ◽  
Ursula Gresser ◽  
Theodor Gunther ◽  
Jürgen Vormann
Keyword(s):  
Haemolytic Anaemia ◽  
Rapid Growth ◽  
Magnesium Deficiency ◽  
Erythropoietic Activity ◽  
Mg Deficiency ◽  
Adequate Diet ◽  
Fe Content ◽  
High Degree

To investigate the mechanism of tissue Fe accumulation in graded Mg deficiency rats were fed on diets of different Mg contents (70, 110, 208, 330, and 850 mg Mg/kg) for 10, 20, and 30 d during rapid growth. There was no significant impact of Mg deficiency or high luminal Mg concentrations on intestinal59Fe transferin vitroorin vivo. Plasma Mg concentrations and body weight started to decrease after 10 d. Significant haemolytic anaemia was observed after 20 d with siderosis in liver and spleen developing in parallel. Anaemia showed no features of Fe deficiency or infiammation. Comparison between the 70 mg Mg/kg group and animals that received the same quantity of a Mg-adequate diet (850 mg Mg/kg) permitted estimation of quantities of Fe liberated by haemolysis and the increased Fe content in liver and spleen. Both variables showed a high degree of correlation, indicating that the excess of liberated haemoglobin Fe was stored in the tissue. The erythropoietic activity was high during rapid growth, i.e. at days 10 and 20 and decreased significantly after 30 d in all except the most Mg-deficient groups. However, haemolytic anaemia developed because even the high erythropoietic activity in the 70 and 110 mg Mg/kg groups was not sutlicient to recycle all haemoglobin Fe liberated by haemolysis. After 30 d of Mg-deficient feeding the erythrocyte Mg content had decreased to 40% of control values. According to the literature Mg-deficient erythrocytes have a decreased survival time which is likely to be the cause of the observed haemolysis.

scholarly journals From the shape of the vertical profile of in vivo fluorescence to Chlorophyll-<i>a</i> concentration

2011 ◽  
Vol 8 (8) ◽  
pp. 2391-2406 ◽  
Author(s):  
A. Mignot ◽  
H. Claustre ◽  
F. D'Ortenzio ◽  
X. Xing ◽  
A. Poteau ◽  
...  
Keyword(s):  
Mixed Layer ◽  
Mixed Layer Depth ◽  
Homogeneous Layer ◽  
Fluorescence Signal ◽  
Vertical Profiles ◽  
Shape Parameters ◽  
Chl A ◽  
In Vivo Fluorescence ◽  
Chl A Fluorescence

Abstract. In vivo fluorescence of Chlorophyll-a (Chl-a) is a potentially useful property to study the vertical distribution of phytoplankton biomass. However the technique is presently not fully exploited as it should be, essentially because of the difficulties in converting the fluorescence signal into an accurate Chl-a concentration. These difficulties arise noticeably from natural variations in the Chl-a fluorescence relationship, which is under the control of community composition as well as of their nutrient and light status. As a consequence, although vertical profiles of fluorescence are likely the most recorded biological property in the open ocean, the corresponding large databases are underexploited. Here with the aim to convert a fluorescence profile into a Chl-a concentration profile, we test the hypothesis that the Chl-a concentration can be gathered from the sole knowledge of the shape of the fluorescence profile. We analyze a large dataset from 18 oceanographic cruises conducted in case-1 waters from the highly stratified hyperoligotrophic waters (surface Chl-a = 0.02 mg m−3) of the South Pacific Gyre to the eutrophic waters of the Benguela upwelling (surface Chl-a = 32 mg m−3) and including the very deep mixed waters in the North Atlantic (Mixed Layer Depth = 690 m). This dataset encompasses more than 700 vertical profiles of Chl-a fluorescence as well as accurate estimations of Chl-a by High Performance Liquid Chromatography (HPLC). Two typical fluorescence profiles are identified, the uniform profile, characterized by a homogeneous layer roughly corresponding to the mixed layer, and the non-uniform profile, characterized by the presence of a Deep Chlorophyll Maximum. Using appropriate mathematical parameterizations, a fluorescence profile is subsequently represented by 3 or 5 shape parameters for uniform or non-uniform profiles, respectively. For both situations, an empirical model is developed to predict the "true" Chl-a concentration from these shape parameters. This model is then used to calibrate a fluorescence profile in Chl-a units. The validation of the approach provides satisfactory results with a median absolute percent deviation of 33 % when comparing the HPLC Chl-a profiles to the Chl-a-calibrated fluorescence. The proposed approach thus opens the possibility to produce Chl-a climatologies from uncalibrated fluorescence profile databases that have been acquired in the past and to which numerous new profiles will be added, thanks to the recent availability of autonomous platforms (profiling floats, gliders and animals) instrumented with miniature fluorometers.

Molecular and physiological mechanisms underlying magnesium-deficiency-induced enlargement, cracking and lignification of Citrus sinensis leaf veins

2020 ◽  
Vol 40 (9) ◽  
pp. 1277-1291 ◽  
Author(s):  
Xin Ye ◽  
Xu-Feng Chen ◽  
Li-Ya Cai ◽  
Ning-Wei Lai ◽  
Chong-Ling Deng ◽  
...  
Keyword(s):  
Cell Wall ◽  
Citrus Sinensis ◽  
Molecular Mechanisms ◽  
Rho Gtpase ◽  
Magnesium Deficiency ◽  
Lignin Biosynthesis ◽  
Starch Accumulation ◽  
Ascorbate Oxidase ◽  
Mg Deficiency ◽  
Leaf Veins

Abstract Little is known about the physiological and molecular mechanisms underlying magnesium (Mg)-deficiency-induced enlargement, cracking and lignification of midribs and main lateral veins of Citrus leaves. Citrus sinensis (L.) Osbeck seedlings were irrigated with nutrient solution at a concentration of 0 (Mg-deficiency) or 2 (Mg-sufficiency) mM Mg(NO3)2 for 16 weeks. Enlargement, cracking and lignification of veins occurred only in lower leaves, but not in upper leaves. Total soluble sugars (glucose + fructose + sucrose), starch and cellulose concentrations were less in Mg-deficiency veins of lower leaves (MDVLL) than those in Mg-sufficiency veins of lower leaves (MSVLL), but lignin concentration was higher in MDVLL than that in MSVLL. However, all four parameters were similar between Mg-deficiency veins of upper leaves (MDVUL) and Mg-sufficiency veins of upper leaves (MSVUL). Using label-free, liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis, we identified 1229 and 492 differentially abundant proteins (DAPs) in MDVLL vs MSVLL and MDVUL vs MSVUL, respectively. Magnesium-deficiency-induced alterations of Mg, nonstructural carbohydrates, cell wall components, and protein profiles were greater in veins of lower leaves than those in veins of upper leaves. The increased concentration of lignin in MDVLL vs MSVLL might be caused by the following factors: (i) repression of cellulose and starch accumulation promoted lignin biosynthesis; (ii) abundances of proteins involved in phenylpropanoid biosynthesis pathway, hormone biosynthesis and glutathione metabolism were increased; and (iii) the abundances of the other DAPs [viz., copper/zinc-superoxide dismutase, ascorbate oxidase (AO) and ABC transporters] involved in lignin biosynthesis were elevated. Also, the abundances of several proteins involved in cell wall metabolism (viz., expansins, Rho GTPase-activating protein gacA, AO, monocopper oxidase-like protein and xyloglucan endotransglucosylase/hydrolase) were increased in MDVLL vs MSVLL, which might be responsible for the enlargement and cracking of leaf veins.

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