External calcium requirements for light induction of chlorophyll accumulation and its enhancement by red light and cytokinin pretreatments in excised etiolated cucumber cotyledons

Planta ◽  
1995 ◽  
Vol 196 (4) ◽  
Author(s):  
Carol Reiss ◽  
SamuelI. Beale
Keyword(s):  
Red Light ◽  
Light Induction ◽  
Chlorophyll Accumulation ◽  
Cucumber Cotyledons ◽  
External Calcium

Red Light Induction of Gibberellin Synthesis in Leaves

Nature ◽  
1968 ◽  
Vol 217 (5128) ◽  
pp. 580-582 ◽  
Author(s):  
D. M. REID ◽  
J. B. CLEMENTS ◽  
D. J. CARR
Keyword(s):  
Red Light ◽  
Light Induction

scholarly journals Red- and Blue-Light Sensing in the Plant Pathogen Alternaria alternata Depends on Phytochrome and the White-Collar Protein LreA

mBio ◽  
2019 ◽  
Vol 10 (2) ◽  
Author(s):  
Olumuyiwa Igbalajobi ◽  
Zhenzhong Yu ◽  
Reinhard Fischer
Keyword(s):  
Blue Light ◽  
Alternaria Alternata ◽  
Red Light ◽  
White Collar ◽  
Nuclear Accumulation ◽  
Model Organisms ◽  
Light Induction ◽  
Content Type ◽  
High Osmolarity ◽  
Light Sensing

ABSTRACT The filamentous fungus Alternaria alternata is a common postharvest contaminant of food and feed, and some strains are plant pathogens. Many processes in A. alternata are triggered by light. Interestingly, blue light inhibits sporulation, and red light reverses the effect, suggesting interactions between light-sensing systems. The genome encodes a phytochrome (FphA), a white collar 1 (WC-1) orthologue (LreA), an opsin (NopA), and a cryptochrome (CryA) as putative photoreceptors. Here, we investigated the role of FphA and LreA and the interplay with the high-osmolarity glycerol (HOG) mitogen-activated protein (MAP) kinase pathway. We created loss-of function mutations for fphA, lreA, and hogA using CRISPR-Cas9 technology. Sporulation was reduced in all three mutant strains already in the dark, suggesting functions of the photoreceptors FphA and LreA independent of light perception. Germination of conidia was delayed in red, blue, green, and far-red light. We found that light induction of ccgA (clock-controlled gene in Neurospora crassa and light-induced gene in Aspergillus nidulans) and the catalase gene catA depended on FphA, LreA, and HogA. Light induction of ferA (a putative ferrochelatase gene) and bliC (bli-3, light regulated, unknown function) required LreA and HogA but not FphA. Blue- and green-light stimulation of alternariol formation depended on LreA. A lack of FphA or LreA led to enhanced resistance toward oxidative stress due to the upregulation of catalases and superoxide dismutases. Light activation of FphA resulted in increased phosphorylation and nuclear accumulation of HogA. Our results show that germination, sporulation, and secondary metabolism are light regulated in A. alternata with distinct and overlapping roles of blue- and red-light photosensors. IMPORTANCE Light controls many processes in filamentous fungi. The study of light regulation in a number of model organisms revealed an unexpected complexity. Although the molecular components for light sensing appear to be widely conserved in fungal genomes, the regulatory circuits and the sensitivity of certain species toward specific wavelengths seem different. In N. crassa, most light responses are triggered by blue light, whereas in A. nidulans, red light plays a dominant role. In Alternaria alternata, both blue and red light appear to be important. In A. alternata, photoreceptors control morphogenetic pathways, the homeostasis of reactive oxygen species, and the production of secondary metabolites. On the other hand, high-osmolarity sensing required FphA and LreA, indicating a sophisticated cross talk between light and stress signaling.

scholarly journals No effect of plant growth retarding compounds and growth stimulators on indolo-3-acetic acid oxidase activity in greening cucumber cotyledons

2015 ◽  
Vol 42 (3) ◽  
pp. 441-452 ◽  
Author(s):  
J. S. Knypl
Keyword(s):  
Oxidase Activity ◽  
Chlorophyll Synthesis ◽  
Lag Phase ◽  
Acid Oxidase ◽  
Iaa Oxidase ◽  
Crude Enzyme Extract ◽  
Chlorophyll Accumulation ◽  
Cucumber Cotyledons ◽  
Amo 1618 ◽  
Molecular Sieving

Cotyledons dissected from 5-day-old etiolated cucumber seedlings were incubated in solutions on AMO-1618, B-Nine, CCC and Phosfon D for 48 h in light. In some tests the retardants were applied in mixed solutions with GA<sub>3</sub> or BAP. IAA oxidase was extracted and purified by means of molecular sieving through a bed of Sephadex G-25. The retardants inhibited chlorophyll synthesis by 50 % or more, and had essentially no effect on IAA oxidase activity per cotyledon basis. GA<sub>3</sub> and BAP also had no effect on enzyme activity in spite of a fact that the compounds stimulated growth of the cotyledons. The crude enzyme extract from B-Nine treated cotyledons showed lower IAA oxidase activity in comparison with the water treated control, the effect being due to a longer lag-phase preceding the initiation of IAA oxidation. KNO<sub>3</sub> strikingly stimulated expansional growth of the cotyledons, the effect being correlated with the accelerated chlorophyll accumulation. KNO<sub>3</sub> had no effect on IAA oxidase activity per cotyledon and decreased it per gram fr wt. It is concluded that [1] the growth rate of cucumber cotyledons is not correlated with IAA oxidase activity, and ;[2] the growth retarding compounds do not affect IAA oxidase system is this tissue.

Phytochrome control of the lag phase of chlorophyll accumulation in Lemna minor

1975 ◽  
Vol 53 (21) ◽  
pp. 2405-2410 ◽  
Author(s):  
Hugh Frick
Keyword(s):  
Lemna Minor ◽  
Red Light ◽  
Lag Phase ◽  
Chlorophyll Accumulation ◽  
Rapid Accumulation ◽  
Lag Period ◽  
Accumulation Phase ◽  
And Control ◽  
Etiolated Plants ◽  
Rate Of Accumulation

The 10- to 12-h lag phase in chlorophyll accumulation preceding the rapid accumulation phase in Lemna minor de-etiolating in the light was eliminated by a red light preillumination given about the length of the lag period before the onset of continuous red light. Neither the rate after the lag nor the extent of cholorophyll accumulation differed between preilluminated and control plants. Both the rate of accumulation in controls and the absolute stimulation by preillumination were shown to depend upon the length of time the etiolated plants had been grown in darkness up to 93 days. Only one photoproduct of preillumination contributed to the elimination of the chlorophyll lag phase, but the effect of red light was only partially (about 60%) nullified by subsequent far-red light.

Phytochromsystem und Lipochinonsynthese in den Plastiden etiolierter Hordeum-Keimlinge Phytochrome System and Synthesis of Lipoquinones in the Plastids of Etiolated Hordeum Seedlings

1975 ◽  
Vol 30 (1-2) ◽  
pp. 64-66 ◽  
Author(s):  
Hartmut K. Lichtenthaler ◽  
Hans K. Kleudgen
Keyword(s):  
Vitamin K ◽  
Ground State ◽  
Red Light ◽  
Light Induction ◽  
Short Pulses ◽  
Concomitant Decrease ◽  
Phytochrome System

Abstract Short pulses of red light induce in etiolated barley seedlings an enhanced synthesis of plastidic benzoquinones and vitamin K1 , which can be reverted by subsequent irradiation with short pulses of far-red. As compared to the dark there is more formation of plastoquinone-9 than α-tocopherol. The enhanced formation of vitamin K1 is coupled with a concomitant decrease in the level of the second naphthoquinone vitamin “K”. The data show that active phytochrome Pfr , also in its ground state, induces the light triggered lipoquinone synthesis which is connected to thylakoid formation. The red light induction of enhanced plastoquinone-9 synthesis cannot be fully reverted by subsequent far-red and seems to be a very fast phytochrome response.

scholarly journals Calcium Variously Mediates the Effect of Cytokinin on Chlorophyll and LHCPII Accumulation During Greening in Barley Leaves and Cucumber Cotyledons

2015 ◽  
Vol 56 (2) ◽  
pp. 27-34 ◽  
Author(s):  
Jolanta Legocka ◽  
Ewa Sobieszczuk-Nowicka
Keyword(s):  
Photosystem Ii ◽  
Channel Blocker ◽  
Indirect Evidence ◽  
Chelating Agent ◽  
Tetraacetic Acid ◽  
Plant Materials ◽  
Hormonal Effect ◽  
Chlorophyll Accumulation ◽  
Barley Leaves ◽  
Cucumber Cotyledons

Abstract During greening, excised etiolated barley leaves and cucumber cotyledons that were depleted of exogenous Ca2+ by a chelating agent (ethylene glycol-bis (beta aminoethyl ether)-N,N,N`N`-tetraacetic acid, EGTA) showed ∼50% reduced chlorophyll (Chl) accumulation and ∼30% accumulation of apoprotein of the light-harvesting chlorophyll a/b-binding protein complex of photosystem II (LHCPII). The Ca2+ channel blocker lanthanum chloride (LaCl3) applied to cucumber cotyledons reduced LHCPII accumulation more than EGTA did. In both plant mate-rials, cytokinins enhanced chlorophyll accumulation by 50-60% and this effect was completely canceled by EGTA application. Hormones significantly increased LHCPII accumulation but EGTA application reduced that effect in barley leaves by ∼30% and in cucumber cotyledons by ∼80%. A similar effect was observed in LaCl3-treated cotyledons. CaCl2 application boosted chlorophyll accumulation in both plant materials. CaCl2 applied together with cytokinin reduced the hormonal effect on chlorophyll accumulation by ∼38% in barley leaves and 23% in cucumber cotyledons, but almost totally inhibited cytokinin-stimulated LHCPII accumulation. Our results indicate that calcium variously mediates the effect of cytokinin on chlorophyll and LHCPII accumulation. Cytokinin-induced enhancement of chlorophyll accumulation seems totally dependent on the exogenous pool of Ca2+, while Ca2+-dependent and Ca2+-independent pathways are involved in the hormonal effect on LHCPII accumulation. The effect of cytokinin on the increase of light-induced LHCPII accumulation appears to be sensitive to exogenously applied Ca2+, which almost totally blocked the hormonal effect. Our results give indirect evidence that the responses to cytokinin and light act on different events leading to Chl and LHCPII accumulation.

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