UV-B Effect on Constituents of Azolla caroliniana

Ibrahim, Mohamed M.; Mostafa, E. M.

doi:10.1515/znc-2007-3-415

Cited by 3 publications

(8 citation statements)

References 27 publications

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“…Rack height, lamp spacing and lamp power were adjusted as described by Ibrahim and Mostafa (2007) . Plants were rotated under the lamp banks to minimize potential effects resulting from microenvironment variations for 6 h. Samples were taken for chemical analyses.…”

Section: Selenium Treatment and Growth Estimationmentioning

confidence: 99%

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The ameliorative effect of selenium on Azolla caroliniana grown under UV-B stress

Mostafa

Hassan

2015

phyto

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Exposure of Azolla plants to UV-B radiation for 6 h resulted in a decrease in biomass and relative growth rate (RGR), which coincided with an increase in doubling time (DT) as compared with the control. Also, the protein content decreased. On the other hand, hydrogen peroxyde (H 2 O 2 ) and malondialdehyde (MDA) accumulated significantly in UV-treated Azolla plants. Conversely, the addition of selenium (Se) at 1 ppm resulted in a significant increase in biomass and protein content of untreated and UV-treated Azolla plants, and a significant reduction in both H 2 O 2 and MDA. Moreover, the addition of Se to UV-treated and untreated Azolla plants resulted in a significant increase in total ascorbate and total glutathione (GSH) contents compared with the control and UV-stressed Azolla plants. Also, glutathione redox potential (GSH/TG) increased significantly in UV-treated Azolla plants in the presence of Se. There also was a significant increase (38%) in ascorbate peroxidase (APX) activity in UV-treated plants compared with the control. APX activity in the presence of Se did not change significantly compared with the control. Glutathione reductase (GR) activity increased significantly in UV-treated Azolla, while glutathione peroxidase (GSH-PX) activity did not. On the other hand, both GSH-PX and GR activity in untreated and UV-treated Azolla plants were significantly enhanced by the application of Se to the nutrient media at a concentration of 1 ppm. Therefore, we can conclude that Se protects Azolla plants from UV-B stress.

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Section: Selenium Treatment and Growth Estimationmentioning

confidence: 99%

“…Ultraviolet radiation also produces oxidative stress that arises from the deleterious effects of active oxygen species (Costa et al 2002;Ibrahim and Mostafa 2007) that react with lipids, pigments, proteins and nucleic acid (Dai et al 1997;Nasibi and M-Kalantari 2005).…”

Section: Introductionmentioning

confidence: 99%

The ameliorative effect of selenium on Azolla caroliniana grown under UV-B stress

Mostafa

Hassan

2015

phyto

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“…Our previous study has shown that, the vegetative growth, the photosynthetic pigments in addition to the UV-absorbing compounds such as phenolics, flavonoids and anthocyanins in Azolla caroliniana were strongly affected by the duration of exposure to UV-B radiation (Ibrahim and Mostafa, 2007). In this study, changes in reservation non-enzymatic antioxidant metabolites and ultrastructure of chloroplast were investigated in relation to UV damage in the aquatic fern Azolla caroliniana.…”

Section: Introductionmentioning

confidence: 93%

“…Plants have evolved mechanisms to avoid and repair UV radiation oxidative stress damage, and the free radicals caused by UV tend to be involved in the induction of antioxidant defense system. In previous studies, it has been concluded that plant growth and biomass accumulation could result from complex interactions between harmful direct and indirect effects of UV and a series of counteracting repair mechanisms (Lesser et al, 1994 andMostafa, 2007). It has been shown that the composition of the aquatic fern Azolla varies profoundly according to environmental conditions and the species (Lumpkin and Plucknett, 2008;Van Hove, 1987 andVan Hove, 1989).…”

Section: Introductionmentioning

confidence: 99%

“…By means of electron microscopy, early stress responses can be observed in the cell structure before the first macroscopic visible symptoms occur (Holopainen et al, 1992). Special emphasis was put on chloroplast ultrastructure because alterations in the chloroplast could lead to changes in carbon assimilation and biomass accumulation (Ibrahim and Mostafa, 2007). Furthermore, it is well established that chloroplast structure is altered by UV-B usually before other cell organelles (Holopainen et al, 1996).…”

Section: Introductionmentioning

confidence: 99%

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HPLC analysis of non-enzymatic antioxidants in Azolla caroliniana (Pteridopsida) subjected to UV-B

Mostafa

Ibrahim

2012

Egyptian Academic Journal of Biological Sciences, H. Botany

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The ultrastructure of chloroplast and quantified antioxidant compounds such as α-tocopherol, ascorbic acid and beta carotene, semi quantitatively by comparing the peak areas of HPLC chromatograms, were affected considerably in response to exposure of Azolla caroliniana to UV-B radiation for 24 and 48 h. The results show that the most striking effect of the enhanced UV-B treatment on the ultrastructure of A. caroliniana was observed after 48 h as markedly widened chloroplast area occupied by large amount of plastoglobuli in stressed fronds. Prolonged UV-B exposure of A. caroliniana for 48 h resulted in a reduction in peaks area for for αtocopherol, ascorbic acid and beta-carotene. The results show that changes in the chromatogram of non-enzymatic antioxidants were correlated with the duration of exposure to UV-B radiation. These antioxidant metabolites play a vital role in protecting A. caroliniana to a certain limit against UV-B radiation.

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Effects of UV-B Radiation on the Chemical Composition of Azolla and Its Decomposition after Returning to the Field and Nitrogen Transformation in Soil

Chang

Liu

et al. 2023

Agronomy

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In the present research, the effects of UV-B radiation (5.00 kJ·m−2) on the chemical composition of Azolla were investigated, and the decomposition of Azolla residues after UV-B radiation, the nitrogen form, enzyme activity, and bacterial community in paddy soil were analyzed. Compared to the natural light treatment, the total nitrogen content of Azolla was significantly increased by 17.0% under UV-B radiation treatment. Compared to returned Azolla grown under natural light, the decomposition rate of cellulose, lignin, and total nitrogen of returned Azolla grown under UV-B radiation significantly increased, which led to an increase in the activities of nitrogen transformation enzymes, including neutral protease, ammonia monooxygenase, nitrogenase, nitrate reductase, and nitrite reductase, and the contents of different nitrogen forms (NH4+-N, NO3−-N, soluble organic nitrogen, and microbial biomass nitrogen) in paddy soil, while N2O emission flux was significantly reduced by 20–30%. The dominant bacteria in soil supplied with Azolla grown under natural light were Firmicutes, Clostridia, Clostridiales, and Lachnospiraceae. However, returning Azolla grown under UV-B radiation to the soil significantly changed the bacterial community structure in soil, resulting in a decrease in the number of ammonifying bacteria, nitrifying bacteria, and nitrogen-fixing bacteria and an increase in the number of denitrifying bacteria, inducing changes in the dominant bacteria to Methanomicrobiales, Methanoregulaceae, and Methanoregula. According to the structural equation model, returning Azolla to the field would reduce N2O emissions by increasing Azolla lignin decomposition and ammonia monooxygenase activity, reducing the number of nitrifying bacteria and reducing nitrite reductase activity in soil. Thus, UV-B radiation can directly change the phytochemical components and their decomposition in soil, thus indirectly affecting the bacterial community structure, enzyme activity, and nitrogen transformation, which play important ecological roles in regulating the nutrient transformation of terrestrial ecosystems.

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UV-B Effect on Constituents of Azolla caroliniana

Cited by 3 publications

References 27 publications

The ameliorative effect of selenium on Azolla caroliniana grown under UV-B stress

The ameliorative effect of selenium on Azolla caroliniana grown under UV-B stress

HPLC analysis of non-enzymatic antioxidants in Azolla caroliniana (Pteridopsida) subjected to UV-B

Effects of UV-B Radiation on the Chemical Composition of Azolla and Its Decomposition after Returning to the Field and Nitrogen Transformation in Soil

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