scholarly journals Persistence of Red Light Induction in Lettuce Seeds of Varying Hydration

1974 ◽  
Vol 53 (3) ◽  
pp. 503-506 ◽  
Author(s):  
Lars Loercher
Keyword(s):  
Red Light ◽  
Light Induction ◽  
Lettuce Seeds

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.

ACTION AND INTERACTION OF MONOCHROMATIC LIGHT ON PHOSPHATE METABOLISM OF GERMINATING LETTUCE SEEDS

1962 ◽  
Vol 40 (7) ◽  
pp. 965-974 ◽  
Author(s):  
Kenneth Surrey
Keyword(s):  
Energy Flow ◽  
Spectral Band ◽  
Red Light ◽  
Monochromatic Light ◽  
Lettuce Seed ◽  
Phosphate Metabolism ◽  
Lettuce Seeds ◽  
Phytochrome System ◽  
Lettuce Seed Germination ◽  
Partial Suppression

A previously described photoresponse of lettuce seed germination to red and far-red light is shown to be paralleled by a response of phosphate metabolic activity: (1) When seeds were continuously irradiated, red light accelerated and far-red suppressed their phosphate uptake and esterification. (2) The influence of monochromatic light on phosphate metabolism of seeds, determined after 36 and 64 hours of germination, respectively, indicated maximum potentiation between 550 and 650 mμ, maximum suppression beyond 700 mμ, and partial suppression at 475 mμ. Stimulation was encountered at 400 mμ, but with shorter wavelengths of the ultraviolet spectrum, suppression appeared again. (3) Photoactivation of phosphate metabolism in response to each of the three loci (550, 600, and 650 mμ, i.e., green, orange, and red light, respectively) of the potentiating spectral band was reversed by far-red (750 mμ) light. These activations and inhibitions could be reversed several times in an alternating sequence. Complete reversibility depended entirely upon the magnitudes of the radiant flux for the two counteracting wavelengths, and this was characteristic for each pair of antagonistic wavelengths. In view of the association of phytochrome with the isolated mitochondria and of the specific manner in which their phosphorylation activity is influenced by light, it is suggested that a part of the energy flow required for cellular development may be channeled through the mitochondrial–phytochrome system.

The growth physics and water relations of red-light-induced germination in lettuce seeds

Planta ◽  
1971 ◽  
Vol 101 (1) ◽  
pp. 1-25 ◽  
Author(s):  
Murray W. Nabors ◽  
Anton Lang
Keyword(s):  
Water Relations ◽  
Red Light ◽  
Lettuce Seeds

scholarly journals (421) Light and Temperature Interactions in Promoting Lettuce Seed Germination

HortScience ◽  
2005 ◽  
Vol 40 (4) ◽  
pp. 1021E-1022
Author(s):  
Samuel Contreras ◽  
David Tay ◽  
Mark Bennett
Keyword(s):  
Red Light ◽  
Light Treatment ◽  
Effect Of Temperature ◽  
Lettuce Seed ◽  
Lettuce Seeds ◽  
Radicle Emergence ◽  
Lettuce Seed Germination ◽  
Temperature Interactions ◽  
Soaking Temperature ◽  
Light Break

Lettuce seeds (Lactuca sativavar. acephalacv. Tango) were used with the objective of determining the effect of temperature, light, and their interactions in promoting germination. Under standard op-timal conditions (20 °C, light), the seed presented 100% germination (radicle emergence 5 d after sowing). Different treatments evaluated germination under dark conditions, with or without a red light break (LB, 28.8 mmol·m-2) 48 h after sowing, and with different combination of temperatures pre- (soaking temperature, ST) and post- (germination temperature, GT) the LB. Germination at constant 20 °C without LB was less than 5%, and with LB, it was around 30%. However, germination was close to 100% at GT of 20 °C when LB was applied after a ST of 10 °C, and around 50% under the same conditions, but without LB. When GT was 30 °C and LB was applied, germination was less than 3% with ST = 30 °C, less than 10% with ST = 20 °C, and around 100% when ST = 10 °C. With ST and GT of 10 °C and 30 °C, respectively, and no LB, germination was less than 5%. Germination at 10 °C constant, with and without LB, was around 90% and 0%, respectively. When ST was 40 °C and LB was applied, germination was around 40% at GT= 20 °C, but less that 3% with GT= 30 °C. In summary, a severe inhibition of germination was observed when seeds were germinated in dark, which was partially reversed by either a light treatment or soaking at 10 °C, and fully reversed when both treatments were applied together. Inhibition of lettuce germination at 30 °C was observed when this temperature was applied after a light treatment, but not when applied before. Possible implications of these results for the phytochrome mechanism of action are discussed.

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