Spectral analysis on origination of the bands at 437 nm and 475.5 nm of chlorophyll fluorescence excitation spectrum in <i>Arabidopsis</i> chloroplasts

Zeng, Lizhang; Wang, Yongqiang; Zhou, Jun

doi:10.1002/bio.3022

Cited by 8 publications

(7 citation statements)

References 28 publications

(35 reference statements)

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“…The value of Fv/Fm was calculated by the formulas (Fm-Fo)/Fm. Chlorophyll was extracted by immersion in 90% ethanol at 65 °C for 2 h. The absorbance at 664 nm and 647 nm were determined with a Lambda 35 UV/VIS Spectrometer (Perkin-Elmer) 28 . The concentration per fresh weight of leaf tissue was calculated according to the formula: micromoles of chlorophyll per milliliter per gram fresh weight = 7.93(A664) + 19.53(A647).…”

Section: Photochemical Efficiency and Chlorophyll Content Measurementmentioning

confidence: 99%

Up-regulation of autophagy by low concentration of salicylic acid delays methyl jasmonate-induced leaf senescence

Yin

Liu

et al. 2020

Sci Rep

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Crosstalk between salicylic acid (SA) and jasmonic acid (JA) signaling plays an important role in regulation of plant senescence. our previous work found that SA could delay methyl jasmonate (MeJA)-induced leaf senescence in a concentration-dependent manner. Here, the effect of low concentration of SA (LCSA) application on MeJA-induced leaf senescence was further assessed. High-throughput sequencing (RNA-Seq) results showed that LCSA did not have dominant effects on the genetic regulatory pathways of basal metabolism like nitrogen metabolism, photosynthesis and glycolysis. the clusterone was applied to identify discrete gene modules based on protein-protein interaction (PPI) network. Interestingly, an autophagy-related (ATG) module was identified in the differentially expressed genes (DEGs) that exclusively induced by MeJA together with LCSA. RT-qPCR confirmed that the expression of most of the determined ATG genes were upregulated by LCSA. Remarkably, in contrast to wild type (Col-0), LCSA cannot alleviate the leaf yellowing phenotype in autophagy defective mutants (atg5-1 and atg7-2) upon MeJA treatment. Confocal results showed that LCSA increased the number of autophagic bodies accumulated in the vacuole during MeJAinduced leaf senescence. Collectively, our work revealed up-regulation of autophagy by LCSA as a key regulator to alleviate MeJA-induced leaf senescence. Senescence in green plants is a complex and orderly regulated process that is crucial for transiting from nutrient assimilation to nutrient remobilization 1-5. During senescence, the most visible characteristic is leaf yellowing, which is the consequence of a succession of changes in cellular physiology including chlorophyll degradation and photosynthetic activity reduction 3,4. Chloroplast as an early senescence signaling response organelle, its dismantling plays an important role in the major nitrogen source recycling and remobilization 6. The progression of leaf senescence can be prematurely induced by multiple environmental and endogenous factors, such as temperature, light, humidity and phytohormones 7. Hormone signaling pathways play roles at all the stages of leaf senescence, including the initiation, progression, and the terminal phases of senescence 7. Recent progresses show that senescence can be coordinately regulated by several phytohormones like cytokinins, ethylene, abscisic acid, salicylic acid (SA), and jasmonic acid (JA) 8-12. However, the detailed molecular mechanisms for these phytohormone signals in plant senescence remain poorly understood. JA has been known as a key plant hormone for promoting senescence, based on the findings that exogenously applied methyl jasmonate (MeJA, methyl ester of JA) leads to a rapid loss of chlorophyll content and accompany with reduction of photochemical efficiency 13,14. Studies with JA-insensitive mutant coronatine insensitive 1 (coi1) that exhibited defective senescence response to MeJA treatment 11 , supporting the notion that JA signaling pathway is crucial for leaf senescence. Some other evi...

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Section: Photochemical Efficiency and Chlorophyll Content Measurementmentioning

confidence: 99%

Up-regulation of autophagy by low concentration of salicylic acid delays methyl jasmonate-induced leaf senescence

Yin

Liu

et al. 2020

Sci Rep

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“…Fluorescence excitation spectra can provide useful information about light absorption and energy transfer by the antenna pigments, processes that could be affected by the PPs oxidation and the losses of PSII photochemical efficiency during the MV-oxidative stress. The excitation spectrum of control leaf discs shows two pronounced peaks, one at 420 that can be assigned to excitation of Chl-a, and the other at 484 nm, associated to the energy transfer from the accessory pigments chlorophyll-b and xanthophylls to chlorophyll-a (Zeng et al 2016) (Fig. 8a).…”

Section: Fluorescence Excitation Spectramentioning

confidence: 99%

Oxidation of polyphenols and inhibition of photosystem II under acute photooxidative stress

Samson

Cerović

Rouby

et al. 2019

Planta

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Main conclusionWe observed a close correlation between the inhibition of photosystem II and the oxidation of polyphenols during an acute oxidative stress in sunflower leaf discs.To assess the physiological significance of polyphenols as antioxidants in planta, we compared the kinetics of polyphenols oxidation with the inhibition of the photosynthetic apparatus in sunflower leaf discs exposed to an acute photooxidative stress. Illumination of leaf discs in presence of methyl viologen induced a rapid and large non-photochemical quenching of chlorophyll-a fluorescence, which was reversed after four hours of treatment as indicated by the ≈30% increases of the steady-state (Fs) and maximal (Fm') levels of chlorophyll-a fluorescence relative to the first hour of treatment. This event coincided with the accelerated decreases of the maximum (Fv/Fm) and effective (ΔF/Fm') quantum yields of photosystem II, and also with the beginning of polyphenols oxidation, estimated by the UV absorbance of methanolic leaf extracts, and supported by the Folin-Ciocalteu method and cyclic voltammetry. The decreases of Fv/Fm and the concentrations of reducing polyphenols were highly correlated (R 2 = 0.877) during the experiment. Coherent with the decrease of UV absorbance of methanolic extracts, polyphenols oxidation resulted in a marked decrease of UV-absorbance of leaf epidermis. Also, polymerization of oxidized polyphenols caused the accumulation of brown pigments in the MVtreated leaf discs, decreasing leaf reflectance, especially at 550 and 740 nm. Fluorescence intensities were also decreased during the MV-treatment. Interestingly, the emission fluorescence ratio F 740 /F 684 (excitation at 550 nm) decreased similarly to Fv/Fm (R 2 = 0.981) due to the brown pigments. Moreover, the excitation fluorescence ratio F 484 /F 680 (emission at 740 nm) was linearly correlated (R 2 = 0.957) to ΔF/Fm', indicating a decrease of efficiency of energy transfer between the antenna pigments to the photosystem II reaction center during the oxidative stress. These results support the view that polyphenols can be effective antioxidants protecting the plants against reactive oxygen species.

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“…Total Chlorophyll was determined as reported by Coombs et al (1987). Chlorophyll was extracted by immersion in 90% ethanol at 65 °C for 2 h. The absorbance at 664 nm and 647 nm were determined with a Lambda 35 UV/VIS Spectrometer (Perkin-Elmer) (Zeng et al, 2016). The concentration per fresh weight of leaf tissue was calculated according to the formula: micromoles of chlorophyll per milliliter per gram fresh weight = 7.93(A664) + 19.53(A647).…”

Section: Photochemical Efficiency and Chlorophyll Content Measurementsmentioning

confidence: 99%

Up-regulation of autophagy by low concentration of salicylic acid delays methyl jasmonate-induced leaf senescence

Yin

Liu²,

et al. 2019

Preprint

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Crosstalk between salicylic acid (SA) and jasmonic acid (JA) signaling plays an important role in molecular regulation of plant senescence. Our previous works found that SA could delay methyl jasmonate (MeJA)-induced leaf senescence in a concentration-dependent manner. Here, the effect of low concentration of SA (LCSA) application on MeJA-induced leaf senescence was further assessed. High-throughput sequencing (RNA-Seq) results showed that LCSA did not have dominant effects on the genetic regulatory pathways of basal metabolism like nitrogen metabolism, photosynthesis and glycolysis. The ClusterONE was applied to identify discrete gene modules based on protein-protein interaction (PPI) network. Interestingly, an autophagy-related (ATG) module was identified in the differentially expressed genes (DEGs) that exclusively induced by MeJA together with LCSA. RT-qPCR confirmed that the expression of most of the determined ATG genes were upregulated by LCSA. Remarkably, in contrast to wild type (Col-0), LCSA cannot alleviate the leaf yellowing phenotype in autophagy defective mutants (atg5-1 and atg7-2) upon MeJA treatment. Confocal results showed that LCSA increased the number of autophagic bodies accumulated in the vacuole during MeJA-induced leaf senescence. Collectively, our work revealed up-regulation of autophagy by LCSA as a key regulator to alleviate MeJA-induced leaf senescence.

show abstract

Spectral analysis on origination of the bands at 437 nm and 475.5 nm of chlorophyll fluorescence excitation spectrum in Arabidopsis chloroplasts

Cited by 8 publications

References 28 publications

Up-regulation of autophagy by low concentration of salicylic acid delays methyl jasmonate-induced leaf senescence

Up-regulation of autophagy by low concentration of salicylic acid delays methyl jasmonate-induced leaf senescence

Oxidation of polyphenols and inhibition of photosystem II under acute photooxidative stress

Up-regulation of autophagy by low concentration of salicylic acid delays methyl jasmonate-induced leaf senescence

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