scholarly journals Substrate Application of 5-Aminolevulinic Acid Enhanced Low-temperature and Weak-light Stress Tolerance in Cucumber (Cucumis sativus L.)

Agronomy ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 472 ◽  
Author(s):  
Ali Anwar ◽  
Jun Wang ◽  
Xianchang Yu ◽  
Chaoxing He ◽  
Yansu Li
Keyword(s):  
Low Temperature ◽  
Stress Tolerance ◽  
Antioxidant Enzyme ◽  
Aminolevulinic Acid ◽  
Light Stress ◽  
Photochemical Quenching ◽  
Antioxidant Enzyme Activities ◽  
Cucumber Seedlings ◽  
Chl A ◽  
Weak Light

5-Aminolevulinic acid (ALA) is a type of nonprotein amino acid that promotes plant stress tolerance. However, the underlying physiological and biochemical mechanisms are not fully understood. We investigated the role of ALA in low-temperature and weak-light stress tolerance in cucumber seedlings. Seedlings grown in different ALA treatments (0, 10, 20, or 30 mg ALA·kg−1 added to substrate) were exposed to low temperature (16/8 ˚C light/dark) and weak light (180 μmol·m−2·s−1 photosynthetically active radiation) for two weeks. Treatment with ALA significantly alleviated the inhibition of plant growth, and enhanced leaf area, and fresh and dry weight of the seedlings under low-temperature and weak-light stress. Moreover, ALA increased chlorophyll (Chl) a, Chl b, and Chl a+b contents. Net photosynthesis rate, stomatal conductance, transpiration rate, photochemical quenching, non-photochemical quenching, actual photochemical efficiency of photosystem II, and electron transport rate were significantly increased in ALA-treated seedlings. In addition, ALA increased root activity and antioxidant enzyme (superoxide dismutase, peroxidase, and catalase) activities, and reduced reactive oxygen species (hydrogen peroxide and superoxide radical) and malondialdehyde accumulation in the root and leaf of cucumber seedlings. These findings suggested that ALA incorporation in the substrate alleviated the adverse effects of low-temperature and weak-light stress, and improved Chl contents, photosynthetic capacity, and antioxidant enzyme activities, and thus enhanced cucumber seedling growth.

scholarly journals Size-dependent susceptibility of lake phytoplankton to light stress: An implication for succession of large green algae in a deep oligotrophic lake

2021 ◽  
Author(s):  
Takehiro Kazama ◽  
Kazuhide Hayakawa ◽  
Takamaru Nagata ◽  
Koichi Shimotori ◽  
Akio Imai ◽  
...  
Keyword(s):  
Algal Blooms ◽  
Light Stress ◽  
Photochemical Efficiency ◽  
Early Summer ◽  
Photochemical Quenching ◽  
P Deficiency ◽  
Chl A ◽  
Psii Photochemistry ◽  
Small Phytoplankton ◽  
Nutrient Bioassay

Field observations of the population dynamics and measurements of photophysiology in Lake Biwa were conducted by size class (< vs. > 30 μm) from early summer to autumn to investigate the relationships between susceptibility to light stress and cell size. Also, a nutrient bioassay was conducted to clarify whether the growth rate and photosystem II (PSII) photochemistry of small and large phytoplankton are limited by nutrient availability. Large phytoplankton, which have lower intracellular Chl-a concentrations, had higher maximum PSII photochemical efficiency (Fv/Fm) but lower non-photochemical quenching (NPQNSV) than small phytoplankton under both dark and increased light conditions. The nutrient bioassay revealed that the PSII photochemistry of small phytoplankton was restricted by N and P deficiency at the pelagic site even at the end of the stratification period, while that of large phytoplankton was not. These results suggest that large phytoplankton have lower susceptibility to PSII photodamage than small phytoplankton due to lower intracellular Chl-a concentrations. The size dependency of susceptibility to PSII photoinactivation may play a key role in large algal blooms in oligotrophic water.

Inhibition of Photosystems I and II in Chilling-Sensitive and Chilling-Tolerant Plants under Light and Low-Temperature Stress

1999 ◽  
Vol 54 (9-10) ◽  
pp. 645-657 ◽  
Author(s):  
Carina Barth ◽  
G. Heinrich Krause
Keyword(s):  
Low Temperature ◽  
Xanthophyll Cycle ◽  
Spinacia Oleracea ◽  
Light Stress ◽  
Fluorescence Emission ◽  
Early Spring ◽  
Psii Efficiency ◽  
Chl A ◽  
Leaf Discs

The responses of photosystems (PS) I and II to light stress at 4 °C and 20 °C were studied in leaf discs from three chilling-sensitive plant species, Cucumis sativus, Cucurbita maxima and Nicotiana tabacum, and in the chilling-tolerant Spinacia oleracea. The chilling-sensitive plants were grown at 24 °C under 80 -120 μmol photons m-2 s-1 (Cucumis and Cucurbita) or 30 μmol photons m-2 s-1 (Nicotiana). Spinacia was cultivated outdoors during winter and early spring. The P700 absorbance change around 820 nm served as a relative measure of PSI activity. The potential efficiency of PSII was determined in dark-adapted leaf discs by means of the ratio of variable to maximum chlorophyll (Chl) a fluorescence emission (Fv/Fᴍ). In Cucurbita, Nicotiana and Spinacia, PSI was not or only slightly inhibited by 2 h illumination with 200 μmol m-2 s-1 at 4 °C or with 2000 μmol m-2 s-1 at 20 °C. In leaves of Cucurbita and Nicotiana, exposure to 2000 μmol photons m-2 s-1 at 4 °C resulted in a decline in PSI activity and potential PSII efficiency approximately to the same extent (about 50% within 2 h). In contrast, in Cucumis, both moderate and high light at low temperature caused a PSI inhibition that proceeded considerably faster than the decline in PSII efficiency. Such preferential photoinhibition of PSI was not observed in the other three species tested. In Spinacia, a lower susceptibility of PSI and PSII to photoinhibition at 4 °C was associated with a faster de-epoxidation kinetics of violaxanthin, as compared to the three chilling-sensitive species. In addition, leaves of Spinacia were characterized by a significantly larger pool of xanthophyll-cycle pigments and a higher content of β-carotene based on Chi a+b. When leaves of Cucurbita were preincubated with methylviologen, which catalyzes formation of superoxide anion radicals at the acceptor side of PSI, the decline in potential PSII efficiency under 2000 μmol photons m-2 s-1 at 20 °C and 4 °C was strongly enhanced, whereas the P700 signal was less affected. Our data demonstrate that in the species tested, PSI may be inhibited in vivo besides PSII under light stress, but preferential photoinhibition of PSI is not a general phenomenon in chilling-sensitive plants. At low temperatures, a reduced function of the xanthophyll cycle and of the antioxidative scavenging system might account for enhanced PSI and PSII inhibition in vivo

scholarly journals Overexpression of GmRIQ2-like (Glyma.04G174400) Enhances the Tolerance of Strong Light Stress and Reduces Photoinhibition in Soybean (Glycine max (L.) Merr.)

Agriculture ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 157
Author(s):  
Jing Deng ◽  
Dongmei Li ◽  
Huayi Yin ◽  
Li Ma ◽  
Jiukun Zhang ◽  
...  
Keyword(s):  
Glycine Max ◽  
Stress Tolerance ◽  
Transmembrane Protein ◽  
Light Stress ◽  
Photochemical Quenching ◽  
Strong Light ◽  
Knock Out ◽  
Soybean Seedlings ◽  
Glycine Max L ◽  
Soybean Plants

Soybean (Glycine max (L.) Merr.) is an important crop that serves as a source of edible oil and protein. However, little is known about its molecular mechanism of adaptation to extreme environmental conditions. Based on the Arabidopsis thaliana sequence database and Phytozome, a soybean gene that had a highly similar sequence to the reduced induction of the non-photochemical quenching2 (AtRIQ2) gene, GmRIQ2-like (accession NO.: Glyma.04G174400), was identified in this study. The gene structure analysis revealed that GmRIQ2-like encoded a transmembrane protein. Elements of the promoter analysis indicated that GmRIQ2-like participated in the photosynthesis and abiotic stress pathways. The subcellular localization results revealed that the protein encoded by GmRIQ2-like was located in chloroplasts. The quantitative real-time (qRT)-PCR results revealed that GmRIQ2-like-overexpression (OE) and -knock-out (KO) transgenic soybean seedlings were cultivated successfully. The relative chlorophyll (Chl) and zeaxanthin contents and Chl fluorescence kinetic parameters demonstrated that GmRIQ2-like dissipated excess light energy by enhancing the non-photochemical quenching (NPQ) and reduced plant photoinhibition. These results suggested that GmRIQ2-like was induced in response to strong light and depressed Chl production involved in soybean stress tolerance. These findings indicate that the transgenic seedlings of GmRIQ2-like could be used to enhance strong light stress tolerance and protect soybean plants from photoinhibition damage. This study will serve as a reference for studying crop photoprotection regulation mechanisms and benefits the research and development of new cultivars.

Exogenous application of 5-aminolevulinic acid improves low-temperature stress tolerance of maize seedlings

2018 ◽  
Vol 69 (6) ◽  
pp. 587 ◽  
Author(s):  
Yi Wang ◽  
Jing Li ◽  
Wanrong Gu ◽  
Qian Zhang ◽  
Lixin Tian ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Low Temperature ◽  
Antioxidant Enzyme ◽  
Temperature Stress ◽  
Aminolevulinic Acid ◽  
Photosynthetic Capacity ◽  
Antioxidant Enzyme Activity ◽  
Low Temperature Stress ◽  
Temperature Sensitive ◽  
Maize Seedlings

The important plant growth regulator 5-aminolevulinic acid (ALA) could promote low-temperature stress tolerance of many plants; however, the underlying mechanisms remain to be elucidated. We investigated the effects of exogenously applied ALA on seedling morphology, antioxidant enzyme activity and photosynthetic capacity of maize (Zea mays L.) seedlings under low-temperature stress. Two cultivars, low-temperature-sensitive cv. Suiyu 13 (SY13) and low-temperature-tolerant cv. Zhengdan 958 (ZD958), were subjected to four treatments: low-temperature without ALA treatment, low-temperature after ALA treatment, normal temperature without ALA treatment, and normal temperature after ALA treatment. Plant morphological growth, proline content, antioxidant enzyme activity and photosynthetic capacity were determined. ALA treatment significantly decreased the inhibitory effects of low-temperature stress on seedling dry weight and increased proline accumulation under low temperatures in ZD958. Pre-application of ALA significantly improved superoxide dismutase and catalase activities in SY13 under low-temperature stress. Furthermore, treating maize seedlings with ALA resulted in significant enhancement of ribulose-1,5-bisphosphate (RuBP) carboxylase activity under low-temperature stress in both cultivars. Pre-treatment with ALA relieved the damage caused by low-temperature stress to maize seedlings, particularly in the low-temperature-sensitive cultivar. Therefore, ALA at appropriate concentrations may be used to prevent reductions in maize crop yield due to low-temperature stress.

scholarly journals 5-Aminolevulinic Acid Improves Nutrient Uptake and Endogenous Hormone Accumulation, Enhancing Low-Temperature Stress Tolerance in Cucumbers

2018 ◽  
Vol 19 (11) ◽  
pp. 3379 ◽  
Author(s):  
Ali Anwar ◽  
Yan Yan ◽  
Yumei Liu ◽  
Yansu Li ◽  
Xianchang Yu
Keyword(s):  
Low Temperature ◽  
Temperature Stress ◽  
Root Length ◽  
Aminolevulinic Acid ◽  
Dry Mass ◽  
Low Temperature Stress ◽  
Night Temperature ◽  
Nutrient Contents ◽  
Chl A ◽  
Mass Accumulation

5-aminolevulinic acid (ALA) increases plant tolerance to low-temperature stress, but the physiological and biochemical mechanisms that underlie its effects are not fully understood. To investigate them, cucumber seedlings were treated with different ALA concentrations (0, 15, 30 and 45 mg/L ALA) and subjected to low temperatures (12/8 °C day/night temperature). The another group (RT; regular temperature) was exposed to normal temperature (28/18 °C day/night temperature). Low-temperature stress decreased plant height, root length, leaf area, dry mass accumulation and the strong seedling index (SSI), chlorophyll contents, photosynthesis, leaf and root nutrient contents, antioxidant enzymatic activities, and hormone accumulation. Exogenous ALA application significantly alleviated the inhibition of seedling growth and increased plant height, root length, hypocotyl diameter, leaf area, and dry mass accumulation under low-temperature stress. Moreover, ALA increased chlorophyll content (Chl a, Chl b, Chl a+b, and Carotenoids) and photosynthetic capacity, net photosynthetic rate (Pn), stomatal conductance (Gs), intercellular CO2 concentration (Ci), and transpiration rate (Tr), as well as the activities of superoxide dismutase (SOD), peroxidase (POD, catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR) enzymes, while decreasing hydrogen peroxide (H2O2), superoxide (O2•−), and malondialdehyde (MDA) contents under low-temperature stress. In addition, nutrient contents (N, P, K, Mg, Ca, Cu, Fe, Mn, and Zn) and endogenous hormones (JA, IAA, BR, iPA, and ZR) were enhanced in roots and leaves, and GA4 and ABA were decreased. Our results suggest the up-regulation of antioxidant enzyme activities, nutrient contents, and hormone accumulation with the application of ALA increases tolerance to low-temperature stress, leading to improved cucumber seedling performance.

scholarly journals Both Multi-Segment Light Intensity and Extended Photoperiod Lighting Strategies, with the Same Daily Light Integral, Promoted Lactuca sativa L. Growth and Photosynthesis

Agronomy ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 857 ◽  
Author(s):  
Hanping Mao ◽  
Teng Hang ◽  
Xiaodong Zhang ◽  
Na Lu
Keyword(s):  
Quantum Yield ◽  
Light Intensity ◽  
Plant Growth ◽  
Light Stress ◽  
Photochemical Quenching ◽  
Daily Light Integral ◽  
Weak Light ◽  
Research On Application ◽  
Non Photochemical Quenching ◽  
Light Integral

With the rise of plant factories around the world, more and more crops are cultivated under artificial light. Studies on effects of lighting strategies on plant growth, such as different light intensities, photoperiods, and their combinations, have been widely conducted. However, research on application of multi-segment light strategies and associated plant growth mechanisms is still relatively lacking. In the present study, two lighting strategies, multi-segment light intensity and extended photoperiod, were compared with a constant light intensity with a 12 h light/12 h dark cycle and the same daily light integral (DLI). Both lighting strategies promoted plant growth but acted via different mechanisms. The multi-segment light intensity lighting strategy promoted plant growth by decreasing non-photochemical quenching (NPQ) of the excited state of chlorophyll and increasing the quantum yield of PSII electron transport (PhiPSII), quantum yield of the carboxylation rate (PhiCO2), and photochemical quenching (qP), also taking advantage of the circadian rhythm. The extended photoperiod lighting strategy promoted plant growth by compensating for weak light stress and increasing light-use efficiency by increasing chlorophyll content under weak light conditions.

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