Light-induced inhibition of sporangial formation of Phytophthora infestans on potato leaves

1975 ◽  
Vol 53 (22) ◽  
pp. 2680-2686 ◽  
Author(s):  
Yigal Cohen ◽  
Helena Eyal ◽  
Tova Sadon
Keyword(s):  
Phytophthora Infestans ◽  
Blue Light ◽  
Red Light ◽  
Continuous Light ◽  
Inhibitory Effect ◽  
Hill Reaction ◽  
Light Conditions ◽  
Temperature Dependent ◽  
Dimethyl Urea ◽  
The Hill

Phytophthora infestans failed to produce sporangia on infected potato leaves under continuous light conditions. Blue light (λmax = 450 nm) was most inhibitory, while red light (λmax = 650 nm) was ineffective in inhibiting sporangial formation. Low intensity of blue light (3.7 μEinstein m−2 s−1) induced about 85% inhibition. The inhibitory effect of blue light upon sporulation was temperature dependent: it increased with rise in the temperature from 10 °C to 25 °C. 3,3,4-Dichlorophenyl-1,1-dimethyl urea (DCMU), which blocks the Hill reaction of photosynthesis, did not enable the fungus to sporulate on leaves under light conditions. Preceding dark treatments did not remove the inhibitory effect of blue light; this suggested that sporulation of the fungus is not a 'dark induction phenomenon.'

Transducing mechanisms between circadian clock and overt rhythms in Gonyaulax

1969 ◽  
Vol 47 (2) ◽  
pp. 299-308 ◽  
Author(s):  
Beatrice M. Sweeney
Keyword(s):  
Electron Flow ◽  
Calvin Cycle ◽  
Continuous Light ◽  
Adenosine Diphosphate ◽  
Inhibitory Effect ◽  
Hill Reaction ◽  
Enzyme Preparations ◽  
Dimethyl Urea ◽  
The Hill

In Gonyaulax polyedra it is possible to measure overt rhythms in luminescence, photosynthesis, and cell division. A common endogenous oscillator appears to control all three processes. The question of concern here is the manner in which the information regarding period and phase is transduced from oscillator to overt rhythm. In the rhythm of photosynthetic capacity, the path of electron flow through systems I and II appears not to be the site of transduction, since there is no rhythm in cells in flashing light, in the Hill reaction, or in sensitivity to such specific inhibitors as dichlorophenyl dimethyl urea (DCMU), and carbonyl cyanide m-chlorophenylhydrazone (CCmP). The probable site of control is in the Calvin cycle, since the activity of the first enzyme in this cycle, ribulose diphosphate dicarboxylase, varies with the phase of the cells from which the enzyme is derived. The low activity of this enzyme in crude extracts from cells in the night phase in continuous light can be overcome by increasing the concentration of bicarbonate in the reaction mixture. In vivo also, increasing the concentration of bicarbonate decreases the amplitude of the rhythm markedly. The activity of mixtures of extracts prepared during the day and the night phase is intermediate between that of either enzyme preparation alone, suggesting that the differences in activity are not caused by the presence of activators or inhibitors. The activity of ribulose diphosphate carboxylase is reduced by high temperature and by the presence of parachloromercuribenzonate (pCMB) and both adenosine triphosphate (ATP) and adenosine diphosphate (ADP), but differences in sensitivity to inhibitors between "day" and "night" enzyme preparations are not observed. The concentration of ATP extractable from cells does not vary with the phase of the rhythm.Transduction in the luminescent rhythm appears to be via changes in the mechanism by which luminescence is stimulated in vivo, since it is possible to obtain large and almost equal amounts of light from cells throughout the rhythmic cycle by the addition of acid. Eliciting luminescence in this way appears to bypass the normal mechanism of stimulation. This conclusion is strengthened by the observation that the inhibitory effect of light on cell luminescence is also eliminated when acid is used.

scholarly journals Interactive Effects of Light Quality and Temperature on Arabidopsis Growth and Immunity

2020 ◽  
Vol 61 (5) ◽  
pp. 933-941
Author(s):  
Xiaoying Liu ◽  
Chunmei Xue ◽  
Le Kong ◽  
Ruining Li ◽  
Zhigang Xu ◽  
...  
Keyword(s):  
Disease Resistance ◽  
Blue Light ◽  
Light Quality ◽  
Red Light ◽  
Complex Interaction ◽  
Hypocotyl Elongation ◽  
Interactive Effects ◽  
Phytochrome B ◽  
Light Conditions ◽  
Effects Of Temperature

Abstract We report here the interactive effects of three light qualities (white, red and blue) and three growth temperatures (16�C, 22�C and 28�C) on rosette growth, hypocotyl elongation and disease resistance in Arabidopsis thaliana. While an increase in temperature promotes hypocotyl elongation irrespective of light quality, the effects of temperature on rosette growth and disease resistance are dependent on light quality. Maximum rosette growth rate under white, red and blue light are observed at 28�C, 16�C and 22�C, respectively. The highest disease resistance is observed at 16�C under all three light conditions, but the highest susceptibility is observed at 28�C for white light and 22�C for red and blue light. Interestingly, rosette growth is inhibited by phytochrome B (PHYB) under blue light at 28�C and by cryptochromes (CRYs) under red light at 16�C. In addition, disease resistance is inhibited by PHYB under blue light and promoted by CRYs under red light. Therefore, this study reveals a complex interaction between light and temperature in modulating rosette growth and disease resistance as well as the contribution of PHYB and CRY to disease resistance.

scholarly journals EFFECT OF COLOUR

2014 ◽  
Vol 2 (3SE) ◽  
pp. 1-5
Author(s):  
Lucky Tonk
Keyword(s):  
Blue Light ◽  
Red Light ◽  
Web Design ◽  
Light Conditions ◽  
Emotional Factor

Colours can stimulate and excite people, increase their appetite, make them feel warm or make them feel tranquil. Red simply makes you excited according to those who study chromo dynamics. Coke’s website is red – it gives you a feel of a lazy, hot summer day – just when you feel the need to drink Coke.There’s more to colours in web design than just the emotional factor. People tend to gamble more under red light conditions than under blue light. Colours have impact on performance. Red lights make people act quicker and feel more powerful, which is not always beneficial, while blue makes people think more before acting. There is a reason STOP signs are red – you need to act right away and stop the vehicle you drive, otherwise you are in danger.

Involvement of Two Different Photoreceptors in the Light Regulation of Glutamine Synthetase Activity in a Chlorophyll-Free Chlorella Mutant

1994 ◽  
Vol 49 (11-12) ◽  
pp. 757-762 ◽  
Author(s):  
Gudrun Meya ◽  
Wolfgang Kowallik
Keyword(s):  
Glutamine Synthetase ◽  
Blue Light ◽  
Red Light ◽  
Light Regulation ◽  
Continuous Light ◽  
Light Irradiation ◽  
Synthetase Activity ◽  
Glutamine Synthetase Activity ◽  
Continuous Irradiation ◽  
Photosynthetic Mutant

Glutamine synthetase (EC 6.3.1.2) activity of a non-photosynthetic mutant of Chlorella kessleri is markedly enhanced under blue and slightly increased under red light. In both cases, the effect is largest after 6 h of irradiation. In blue light, saturation is reached at about 10 μEm-2 s-1; in red light, it is not even indicated at 62 μE m-2 s-1.Semilogarithmic plots of both intensity dependencies reveal different slopes, indicating envolvement of two separate photoreceptors. This feature is supported by different effects of pulse irradiation: The response to 15 min of red light irradiation (λmax 650 nm) increases in subsequent darkness. It reaches the same value as in continuous light after 6 h. The response to 15 min of blue light irradiation (λmax 441 nm) increases also in subsequent darkness. However, after 6 h it reaches only 30% of the value obtained by continuous irradiation.It is concluded that, glutamine synthetase of Chlorella is controlled by two different photoreceptors both independent of photosynthesis. There is evidence of two forms of glutamine synthetase, the intracellular distribution and specific light regulations of these are discussed.

Die Wirkung von Simazin auf die Bildung der plastidären Prenyllipide in Keimlingen von Hordeum vulgare L./Effect of Simazine on Formation of Chloroplasts Prenyllipids in Seedlings of H ordeum vulgare L.

1979 ◽  
Vol 34 (1-2) ◽  
pp. 110-113 ◽  
Author(s):  
H. K. Kleudgen
Keyword(s):  
Chlorophyll A ◽  
Photosynthetic Activity ◽  
Red Light ◽  
Hill Reaction ◽  
Common Site ◽  
Hordeum Vulgare L ◽  
Hill Activity ◽  
Multiple Process ◽  
The Hill ◽  
Β Carotene

Abstract Barley seedlings were grown for 7, 10 or 13 days under continuous white light (Fluora lamps) on a nutrient solution containing simazine (2-chloro-4,6-bis-(ethylamino)-s-triazine, 10, 100 μᴍ) . Accumulation of chlorophylls and in part of carotenoids was increasingly enhanced depending on age and concentrations applied. The ratio chlorophyll a/b decreased on this line in 10 and 13 day old plants, the ratio xanthophylls/β-carotene and the ratio chlorophyll a/prenylquinones (plasto-quinone-90X. + red. , α-tocopherol, α-tocoquinone) increased. The way how these prenyllipid ratios are changed in 10 and 13 day old plants is characteristic of a shade type adaptation, as it was shown earlier for other herbicides inhibiting photosystem II.In 7 day old plants the ratio chlorophyll a/prenylquinones decreased. Photosynthetic activity (Hill-reaction) was enhanced in the simazine plants. The ratio chlorophyll a/b was higher, the ratio xanthophylls/β-carotene was lower than in the older seedlings.Similar changes of prenyllipid ratios like in 7 day seedlings and a higher Hill activity were also found in plants grown under blue light (sun type adaptation) as compared to red light (shade type adaptation). This points to similar metabolic changes in the chloroplasts which could be related to a common site of regulation, perhaps the endogenuous cytokinins. The Hill activity, increasing with age in the 10 and 13 day plants, indicates that the mode of action of simazine may be a multiple process resulting to a parallel formation of shade type and sun type characteristics.

scholarly journals Effect of herbicides on photosynthetic electron transport and on the growth of the alga Scenedesmus quadricauda

2015 ◽  
Vol 45 (1–2) ◽  
pp. 101-110
Author(s):  
W. Hendrich ◽  
Z> Kubiak ◽  
K. Jurajda ◽  
M. Pawlaczyk-Szpilowa
Keyword(s):  
Electron Transport ◽  
Mechanism Of Action ◽  
Photosynthetic Electron Transport ◽  
Inhibitory Effect ◽  
Scenedesmus Quadricauda ◽  
Hill Reaction ◽  
The Hill ◽  
Alga Scenedesmus Quadricauda

The inhibitory effect of herbicides on the Hill reaction (with 2,6-dichloro-phenol-indophenol as acceptor) and their influence on development of the alga <i>Scenedesmus quadricauda</i> was studied. The following herbicides were tested: 2,4-D, Gramoxone, Afalon, Kresamone, CIPC and Simazine. The results are discussed in terms of the mechanism of action of the investigated herbicides.

scholarly journals Color-Specific Recovery to Extreme High-Light Stress in Plants

Life ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 812
Author(s):  
Débora Parrine ◽  
Todd M. Greco ◽  
Bilal Muhammad ◽  
Bo-Sen Wu ◽  
Xin Zhao ◽  
...  
Keyword(s):  
Blue Light ◽  
Light Stress ◽  
Red Light ◽  
Light Treatment ◽  
High Light ◽  
Mrna Levels ◽  
Light Conditions ◽  
High Light Stress ◽  
General Response ◽  
The Impact

Plants pigments, such as chlorophyll and carotenoids, absorb light within specific wavelength ranges, impacting their response to environmental light changes. Although the color-specific response of plants to natural levels of light is well described, extreme high-light stress is still being discussed as a general response, without considering the impact of wavelengths in particular response processes. In this study, we explored how the plant proteome coordinated the response and recovery to extreme light conditions (21,000 µmol m−2 s−1) under different wavelengths. Changes at the protein and mRNA levels were measured, together with the photosynthetic parameters of plants under extreme high-light conditions. The changes in abundance of four proteins involved in photoinhibition, and in the biosynthesis/assembly of PSII (PsbS, PsbH, PsbR, and Psb28) in both light treatments were measured. The blue-light treatment presented a three-fold higher non-photochemical quenching and did not change the level of the oxygen-evolving complex (OEC) or the photosystem II (PSII) complex components when compared to the control, but significantly increased psbS transcripts. The red-light treatment caused a higher abundance of PSII and OEC proteins but kept the level of psbS transcripts the same as the control. Interestingly, the blue light stimulated a more efficient energy dissipation mechanism when compared to the red light. In addition, extreme high-light stress mechanisms activated by blue light involve the role of OEC through increasing PsbS transcript levels. In the proteomics spatial analysis, we report disparate activation of multiple stress pathways under three differently damaged zones as the enriched function of light stress only found in the medium-damaged zone of the red LED treatment. The results indicate that the impact of extreme high-light stress on the proteomic level is wavelength-dependent.

scholarly journals Blue Light Perception by Both Roots and Rhizobia Inhibits Nodule Formation in Lotus japonicus

2016 ◽  
Vol 29 (10) ◽  
pp. 786-796 ◽  
Author(s):  
Aya Shimomura ◽  
Ayumi Naka ◽  
Nobuyuki Miyazaki ◽  
Sayaka Moriuchi ◽  
Susumu Arima ◽  
...  
Keyword(s):  
Blue Light ◽  
Red Light ◽  
Lotus Japonicus ◽  
Inhibitory Effect ◽  
Nodule Development ◽  
Nodule Formation ◽  
Mesorhizobium Loti ◽  
Empty Vector ◽  
Legume Nodulation ◽  
Strong Inhibitory Effect

In many legumes, roots that are exposed to light do not form nodules. Here, we report that blue light inhibits nodulation in Lotus japonicus roots inoculated with Mesorhizobium loti. Using RNA interference, we suppressed the expression of the phototropin and cryptochrome genes in L. japonicus hairy roots. Under blue light, plants transformed with an empty vector did not develop nodules, whereas plants exhibiting suppressed expression of cry1 and cry2 genes formed nodules. We also measured rhizobial growth to investigate whether the inhibition of nodulation could be caused by a reduced population of rhizobia in response to light. Although red light had no effect on rhizobial growth, blue light had a strong inhibitory effect. Rhizobial growth under blue light was partially restored in signature-tagged mutagenesis (STM) strains in which LOV-HK/PAS- and photolyase-related genes were disrupted. Moreover, when Ljcry1A and Ljcry2B-silenced plants were inoculated with the STM strains, nodulation was additively increased. Our data show that blue light receptors in both the host plant and the symbiont have a profound effect on nodule development. The exact mechanism by which these photomorphogenetic responses function in the symbiosis needs further study, but they are clearly involved in optimizing legume nodulation.

Basis for Synergism of Atrazine and Alachlor Combinations on Japanese Millet

Weed Science ◽  
1975 ◽  
Vol 23 (1) ◽  
pp. 43-48 ◽  
Author(s):  
I. O. Akobundu ◽  
W. B. Duke ◽  
R. D. Sweet ◽  
P. L. Minotti
Keyword(s):  
Protein Synthesis ◽  
Synergistic Effect ◽  
Inhibitory Effect ◽  
Hill Reaction ◽  
Chloroplast Protein ◽  
Physiological Processes ◽  
Herbicide Mixture ◽  
The Hill ◽  
Hill Reaction Activity ◽  
Chloroplast Protein Synthesis

The effect of atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] and alachlor [2-chloro-2′,6′-diethyl-N-(methoxymethyl)acetanilide] combinations on various physiological processes was studied in order to establish a basis for the synergistic effect of this mixture on Japanese millet [Echinochloa crus-galli(L.) Beauv. var.frumentaceaL.]. In contrast to atrazine, alachlor had no effect on the Hill reaction activity of isolated Japanese millet chloroplasts. When used in combination with atrazine, alachlor had no influence on the inhibitory effect of atrazine on the Hill reaction. Atrazine and alachlor combinations reduced chloroplast protein and severely inhibited chloroplast protein synthesis relative to protein synthesis by other particulate fractions. This inhibition appears to be the basis for the synergistic effect of this herbicide mixture on Japanese millet. Although the mechanism of action of the herbicide mixture is not understood, it does not seem to involve inhibition of atrazine detoxification.

Sign in / Sign up

Export Citation Format

Share Document