Light regulation of endogenous salicylic acid levels in hypocotyls of Helianthus annuus seedlings

Botany ◽  
2010 ◽  
Vol 88 (7) ◽  
pp. 668-674 ◽  
Author(s):  
Leonid V. Kurepin ◽  
Linda J. Walton ◽  
David M. Reid ◽  
C. C. Chinnappa
Keyword(s):  
Salicylic Acid ◽  
Helianthus Annuus ◽  
Leaf Growth ◽  
Stem Elongation ◽  
Light Regulation ◽  
Shade Avoidance ◽  
Light Conditions ◽  
Direct Role ◽  
Positive Effects

Plants growing in canopy shade typically exhibit increased stem elongation and reduced leaf growth. This is as a result of direct interactions between plant photoreceptors sensing the change (reduction) in the ratio of red to far-red (R/FR) light and photosynthetically active radiation (PAR) and plant hormones, and regulating these morphological traits. The effect of the varying light conditions found in shade on endogenous salicylic acid (SA) content was tested, and the possible role of SA in shade avoidance by sunflower ( Helianthus annuus L.) hypocotyls was examined. A logarithmic increase in PAR irradiance levels increased endogenous SA levels roughly 10-fold. Separation of individual light wavelengths (R, FR, and blue) constituting the PAR irradiance of sunlight, established that only FR light had significant and positive effects on endogenous SA levels. Further, a low R/FR ratio significantly increased the endogenous SA content in hypocotyls compared with normal and high R/FR ratios. Uncoupling the effect of R/FR ratio and PAR irradiance on endogenous SA content demonstrated that PAR irradiance is a much stronger signal than FR light-enrichment. Thus, while a low R/FR ratio increases the SA content in sunflower hypocotyls, low PAR, the other component of canopy shade, decreases the SA content much more effectively than low R/FR ratio increases it. Therefore, it appears that SA probably has no direct role in shade avoidance effects.

Stem and leaf growth of alpine sun and prairie shade ecotypes of Stellaria longipes under different photoperiods: role of ethylene

2006 ◽  
Vol 84 (9) ◽  
pp. 1496-1502 ◽  
Author(s):  
Linda J. Walton ◽  
Leonid V. Kurepin ◽  
David M. Reid ◽  
C.C. Chinnappa
Keyword(s):  
Leaf Growth ◽  
Stem Elongation ◽  
Leaf Length ◽  
Leaf Expansion ◽  
Alpine Plants ◽  
Growth Responses ◽  
Stellaria Longipes ◽  
Length And Area ◽  
Radiation Conditions

Plant ecotypes of Stellaria longipes Goldie from competitive, shade-adapted prairie habitat and less competitive, nonshaded alpine habitat were subjected to shortened or extended photoperiod conditions. Increasing daylength was positively correlated to increased stem elongation in both ecotypes. Leaf length and area for shade (prairie) plants was significantly altered with increased photoperiods, whereas sun (alpine) plants exhibited minimal leaf expansion in response to increased photoperiod. Increased ethylene evolution in the alpine genotype during rapid stem elongation and extended photoperiods suggests that ethylene plays a growth regulatory role in this sun-adapted genotype. The prairie genotype evolved less ethylene during these same periods, indicating either a diminished requirement for elevated ethylene to effect elongation and leaf expansion responses or possibly increased ethylene sensitivity because of interactions with other hormones, such as gibberellin or auxin. The sun genotype consistently produced more ethylene than the shade genotype under all photoperiod treatments. We conclude that photoperiod alters stem elongation and leaf expansion responses; similar trends were observed for extended photoperiods as were observed for shaded conditions, specifically low light intensity (photosynthetically active radiation) conditions. Further, ethylene levels altered during these responses, especially in sun-adapted alpine plants, which suggests that ethylene is involved in these growth responses.

The role of endogenous ethylene in the expansion of Helianthus annuus leaves

1997 ◽  
Vol 75 (3) ◽  
pp. 501-508 ◽  
Author(s):  
Siew Hwee Lee ◽  
David M. Reid
Keyword(s):  
Carboxylic Acid ◽  
Helianthus Annuus ◽  
Acid Treatment ◽  
Leaf Growth ◽  
Leaf Expansion ◽  
Silver Thiosulphate ◽  
Ethylene Concentration ◽  
Endogenous Ethylene ◽  
Ethylene Action

The possible role of ethylene in leaf expansion of the primary leaves of sunflower plants (Helianthus annuus) was studied. Our lowest application of ethephon promoted expansion of primary leaves. Higher concentrations of ethephon, and a range of concentrations of 1-aminocyclopropane-1-carboxylic acid, increased endogenous ethylene concentration and caused a reduction in the area of the primary leaves. The inhibition in leaf expansion induced by ethephon and 1-aminocyclopropane-1-carboxylic acid was reversed by pretreating the plants with an inhibitor of ethylene action, namely silver thiosulphate. Treating leaves with lower concentrations of aminoefhoxyvinylglycine reduced ethylene production and stimulated leaf expansion. This effect of aminoethoxyvinylglycine could be nullified by pretreating the plants with 1-aminocyclopropane-1-carboxylic acid. Treatment with silver thiosulphate enhanced leaf expansion. This indicates that endogenous ethylene normally plays a significant role in leaf expansion. Flooded and gravistimulated plants produced more ethylene and had smaller leaves. This could suggest that the increased ethylene is the main cause of the slowed leaf growth, however, only in some cases were we able to partially reverse the effect of flooding with silver thiosulphate. This indicates that there are probably many factors, in addition to increased ethylene, that inhibit leaf expansion in flooded and gravistimulated plants. Key words: ethylene, leaf expansion.

scholarly journals Shade suppresses wound-induced leaf repositioning through a mechanism involving PHYTOCHROME KINASE SUBSTRATE (PKS) genes

2021 ◽  
Author(s):  
Anne-Sophie Fiorucci ◽  
Olivier Michaud ◽  
Emanuel Schmid-Siegert ◽  
Martine Trevisan ◽  
Laure Allenbach Petrolati ◽  
...  
Keyword(s):  
Leaf Growth ◽  
Expression Patterns ◽  
Defense Responses ◽  
Potential Interaction ◽  
Shade Avoidance ◽  
Mechanical Wounding ◽  
Kinase Substrate ◽  
Wound Signal ◽  
The Relationship

Shaded plants challenged with herbivores or pathogens prioritize growth over defense. However, most experiments have focused on the effect of shading light cues on defense responses. To investigate the potential interaction between shade-avoidance and wounding-induced Jasmonate (JA)-mediated signaling on leaf growth and movement, we used repetitive mechanical wounding of leaf blades to mimic herbivore attacks. Phenotyping experiments with combined treatments on Arabidopsis thaliana rosettes revealed that shade strongly inhibits the wound effect on leaf elevation. By contrast, petiole length is reduced by wounding both in the sun and in the shade. Thus, the relationship between the shade and wounding/JA pathways varies depending on the physiological response, implying that leaf growth and movement can be uncoupled. Using RNA-sequencing, we identified genes with expression patterns matching the hyponastic response (opposite regulation by both stimuli, interaction between treatments with shade dominating the wound signal). Among them were genes from the PKS (Phytochrome Kinase Substrate) family, which was previously studied for its role in phototropism and leaf positioning. Interestingly, we observed reduced shade suppression of the wounding effect in pks2pks4 double mutants while a PKS4 overexpressing line showed constitutively elevated leaves and was less sensitive to wounding. Our results indicate a trait-specific interrelationship between shade and wounding cues on Arabidopsis leaf growth and positioning. Moreover, we identify PKS genes as integrators of external cues in the control of leaf hyponasty further emphasizing the role of these genes in aerial organ positioning.

On the Methodology of Cartel agreements analysis

2014 ◽  
pp. 53-64 ◽  
Author(s):  
E. Andreyashchenko ◽  
A. Zazdravnykh
Keyword(s):  
Economic Models ◽  
Social Consequences ◽  
Positive Effects ◽  
Industrial Markets

This article is an attempt of summarizing key economic approaches to cartel agreements analysis, its stability, ways of estimating social consequences of cartel agreements. It is alleged that the traditional way of understanding the cartels’ role as completely negative is not accurate; this type of inter-corporate agreements may also bring positive effects on industrial markets. Typical limits of analytical apparatus, contradictions that appear while interpreting results of specific economic models are also represented in the article, as well as substantiation of a discrete role of pricing factor within the analysis of anti-competitive agreements.

Peranan Negara dalam Liberalisasi Ekonomi Vietnam: Analisis Terhadap Dasar Doi Moi 1986

2020 ◽  
Author(s):  
Muhamad Helmy Sabtu ◽  
◽  
Khairul Azman Mohamad Suhaimy ◽  
Nurul Aimi Razali
Keyword(s):  
Gender Equality ◽  
Foreign Investment ◽  
Economic Performance ◽  
Level Of Education ◽  
Positive Effects ◽  
Doi Moi ◽  
The People ◽  
Effective Policy ◽  
Economic Landscape

This article analyses the role of state in the policy of economic liberalisation in Vietnam. Doi Moi, which was launched in 1986, is a very influential and effective policy in changing the socio-economic landscape of the people in the country. The results of this study prove that there are positive effects on the increase of foreign investment inflows, the eradication of starvation and unruly poverty, the increase of level of education, the improvement of gender equality and women's rights as well as the sustainability of the environment after Doi Moi is implemented. Through Doi Moi, Vietnam is moving towards a developing country status with good economic performance both at the Southeast Asian and global.

scholarly journals Innovation Capabilities and the Performance of Start-Ups in Korea: The Role of Government Support Policies

2021 ◽  
Vol 13 (11) ◽  
pp. 6009
Author(s):  
Se-Kyoung Choi ◽  
Sangyun Han ◽  
Kyu-Tae Kwak
Keyword(s):  
Firm Performance ◽  
Financial Support ◽  
Political Support ◽  
Sustainable Growth ◽  
Government Support ◽  
Role Of Government ◽  
Positive Effects ◽  
Start Up ◽  
Start Ups

What kind of capacity is needed to improve the performance of start-ups? How effective are government support policies in improving start-up performance? Start-ups are critical firm group for ensuring the prospective and sustainable growth of an economy, and thus many countries’ governments have established support policies and they are likely to engage more widely in forward-looking political support activities to ensure further growth and expansion. In this paper, the effect of innovation capabilities and government support policies on start-up performance is examined. We used an unbalanced panel data analysis with a random effect generalized least squares. We investigated the effect of government support policies on 4368 Korean start-ups. The findings indicated that technology and knowledge capabilities had positive effects on the sales performance of start-ups, and government financial support positively affected the relationship between knowledge capability and firm performance. However, when government financial support increased, marketing capability was negatively associated with firm performance. These results demonstrate the significant role of government financial support, including its crowding in but also its crowding out effect. Practical implications: To be more effective, governments should employ innovation-driven entrepreneurship policy approaches to support start-ups. To improve their performance, start-ups need to increase their technology and knowledge capabilities. This study extends recent efforts to understand more fully the effect of government support policies on start-ups differing in their technology, knowledge, and marketing capabilities.

scholarly journals Salicylic Acid Accumulation Controlled by LSD1 Is Essential in Triggering Cell Death in Response to Abiotic Stress

Cells ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 962
Author(s):  
Maciej Jerzy Bernacki ◽  
Anna Rusaczonek ◽  
Weronika Czarnocka ◽  
Stanisław Karpiński
Keyword(s):  
Cell Death ◽  
Salicylic Acid ◽  
Abiotic Stress ◽  
Wild Type ◽  
Pr Genes ◽  
Genes Expression ◽  
Salicylic Acid Accumulation ◽  
Cell Death Phenotype ◽  
Insight Into

Salicylic acid (SA) is well known hormonal molecule involved in cell death regulation. In response to a broad range of environmental factors (e.g., high light, UV, pathogens attack), plants accumulate SA, which participates in cell death induction and spread in some foliar cells. LESION SIMULATING DISEASE 1 (LSD1) is one of the best-known cell death regulators in Arabidopsis thaliana. The lsd1 mutant, lacking functional LSD1 protein, accumulates SA and is conditionally susceptible to many biotic and abiotic stresses. In order to get more insight into the role of LSD1-dependent regulation of SA accumulation during cell death, we crossed the lsd1 with the sid2 mutant, caring mutation in ISOCHORISMATE SYNTHASE 1(ICS1) gene and having deregulated SA synthesis, and with plants expressing the bacterial nahG gene and thus decomposing SA to catechol. In response to UV A+B irradiation, the lsd1 mutant exhibited clear cell death phenotype, which was reversed in lsd1/sid2 and lsd1/NahG plants. The expression of PR-genes and the H2O2 content in UV-treated lsd1 were significantly higher when compared with the wild type. In contrast, lsd1/sid2 and lsd1/NahG plants demonstrated comparability with the wild-type level of PR-genes expression and H2O2. Our results demonstrate that SA accumulation is crucial for triggering cell death in lsd1, while the reduction of excessive SA accumulation may lead to a greater tolerance toward abiotic stress.

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