Short episodes of high temperature (HT) stress during reproductive stages of development cause significant yield losses in wheat (Triticum aestivum L.). Two independent experiments were conducted to ...quantify the effects of HT during anthesis and grain filling periods on photosynthesis, leaf lipidome, and yield traits in wheat. In experiment I, wheat genotype Seri82 was exposed to optimum temperature (OT; 22/14 °C; day/night) or HT (32/22 °C) for 14 d during anthesis stage. In experiment II, the plants were exposed to OT or HT for 14 d during the grain filling stage. During the HT stress, chlorophyll index, thylakoid membrane damage, stomatal conductance, photosynthetic rate and leaf lipid composition were measured. At maturity, grain yield and its components were quantified.
HT stress during anthesis or grain filling stage decreased photosynthetic rate (17 and 25%, respectively) and grain yield plant
(29 and 44%, respectively), and increased thylakoid membrane damage (61 and 68%, respectively) compared to their respective control (OT). HT stress during anthesis or grain filling stage increased the molar percentage of less unsaturated lipid species 36:5- monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG). However, at grain filling stage, HT stress decreased the molar percentage of more unsaturated lipid species (36:6- MGDG and DGDG). There was a significant positive relationship between photosynthetic rate and grain yield plant
, and a negative relationship between thylakoid membrane damage and photosynthetic rate.
The study suggests that maintaining thylakoid membrane stability, and seed-set per cent and individual grain weight under HT stress can improve the photosynthetic rate and grain yield, respectively.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
High temperature is a major abiotic stress that limits wheat (Triticum aestivum L.) productivity. Variation in levels of a wide range of lipids, including stress-related molecular species, oxidative ...damage, cellular organization and ultrastructural changes were analyzed to provide an integrated view of the factors that underlie decreased photosynthetic rate under high temperature stress. Wheat plants of cultivar Chinese Spring were grown at optimum temperatures (25/15 °C, maximum/minimum) until the onset of the booting stage. Thereafter, plants were exposed to high temperature (35/25 °C) for 16 d.
Compared with optimum temperature, a lower photosynthetic rate was observed at high temperature which is an interplay between thylakoid membrane damage, thylakoid membrane lipid composition, oxidative damage of cell organelle, and stomatal and non-stomatal limitations. Triacylglycerol levels were higher under high temperature stress. Polar lipid fatty acyl unsaturation was lower at high temperature, while triacylglycerol unsaturation was the same at high temperature and optimum temperature. The changes in lipid species indicates increases in activities of desaturating, oxidizing, glycosylating and acylating enzymes under high temperature stress. Cumulative effect of high temperature stress led to generation of reactive oxygen species, cell organelle and membrane damage, and reduced antioxidant enzyme activity, and imbalance between reactive oxygen species and antioxidant defense system.
Taken together with recent findings demonstrating that reactive oxygen species are formed from and are removed by thylakoid lipids, the data suggest that reactive oxygen species production, reactive oxygen species removal, and changes in lipid metabolism contribute to decreased photosynthetic rate under high temperature stress.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The role of selenium nanoparticles (Se-NPs) in the mitigation of high-temperature (HT) stress in crops is not known. The uptake, toxicity and physiological and biological effects of Se-NPs under HT ...were investigated in grain sorghum Sorghum bicolor (L.) Moench. Se-NPs of size 10–40 nm were synthesized and characterized to indicate nanocrystalline structure. A toxicity assay showed that Se-NPs concentration inducing 50% cell mortality (TC50) was 275 mg L–1. Translocation study indicated that Se-NPs can move from root to shoot of sorghum plants. Foliar spray of 10 mg L–1 Se-NPs during the booting stage of sorghum grown under HT stress stimulated the antioxidant defense system by enhancing antioxidant enzymes activity. Furthermore, it decreased the concentration of signature oxidants. Se-NPs facilitated higher levels of unsaturated phospholipids. Se-NPs under HT stress improved the pollen germination percentage, leading to a significantly increased seed yield. The increased antioxidant enzyme activity and decreased content of oxidants in the presence of Se-NPs were greater under HT (38/28 °C) than under optimum temperature conditions (32/22 °C). In conclusion, Se-NPs can protect sorghum plants by enhanced antioxidative defense system under HT stress.
In recent decades, nanoparticles have been intensively applied in agriculture. Two experiments were carried out to demonstrate the potential of nano‐iron oxide (n‐Fe2O3) as seed treatment (soaking ...and priming) at different concentrations (0, 10, 50, 100 and 500 mg/L) for enhancing sorghum (Sorghum bicolor (L.) Moench) germination and seedling growth under non‐stressed conditions (Experiment I), and to investigate the impacts of n‐Fe2O3 seed priming treatments (0, 10, 50, 100 and 500 mg/L) on growth, chlorophyll content, chlorophyll a fluorescence, gas exchange, water relations and lipid peroxidation under salt stress (150 mmol NaCl solution) (Experiment II). Results indicated that seed soaking with n‐Fe2O3 at 10 mg/L was the best treatment in improving speed and per cent of germination, while seed priming with n‐Fe2O3 at 50 and 100 mg/L was the most effective treatment in improving seedling (12 days old) growth. Salt stress decreased chlorophyll content, photosynthetic rate, stomatal conductance, transpiration rate, relative water content, osmotic potential and growth, along with increased lipid peroxidation. Among chlorophyll a fluorescence parameters, the photosynthetic performance index of PSII (PIABS) was the most salt‐responsive. Seed priming with n‐Fe2O3 at 500 mg/L increased sorghum growth (45 days old), through increased photosystem II efficiency, chlorophyll index, photosynthetic rate and relative water content with decreased lipid peroxidation. Overall, this study indicated that use of n‐Fe2O3 as a pre‐sowing seed treatment can enhance germination and seedling growth of sorghum and protect from negative impacts of salinity stress.
Oxidative stress is commonly induced when plants are grown under high temperature (HT) stress conditions. Selenium often acts as an antioxidant in plants; however, its role under HT-induced oxidative ...stress is not definite. We hypothesize that selenium application can partly alleviate HT-induced oxidative stress and negative impacts of HT on physiology, growth and yield of grain sorghum
Sorghum bicolor (L.) Moench. Objectives of this study were to investigate the effects of selenium on (a) leaf photosynthesis, membrane stability and antioxidant enzymes activity and (b) grain yield and yield components of grain sorghum plants grown under HT stress in controlled environments. Plants were grown under optimal temperature (OT; 32/22
°C daytime maximum/nighttime minimum) from sowing to 63 days after sowing (DAS). All plants were foliar sprayed with sodium selenate (75
mg
L
−1) at 63 DAS, and HT stress (40/30
°C) was imposed from 65 DAS through maturity. Data on physiological, biochemical and yield traits were measured. High temperature stress decreased chlorophyll content, chlorophyll
a fluorescence, photosynthetic rate and antioxidant enzyme activities and increased oxidant production and membrane damage. Decreased antioxidant defense under HT stress resulted in lower grain yield compared with OT. Application of selenium decreased membrane damage by enhancing antioxidant defense resulting in higher grain yield. The increase in antioxidant enzyme activities and decrease in reactive oxygen species (ROS) content by selenium was greater in HT than in OT. The present study suggests that selenium can play a protective role during HT stress by enhancing the antioxidant defense system.
► High temperature stress increases oxidative damage in leaves. ► High temperature stress decreased antioxidant enzyme activity. ► High temperature stress decreased photosynthetic rates and grain yield. ► Foliar application of Se enhanced antioxidant defense system. ► Selenium can play a protective role during high temperature stress conditions.
Background and aim
Mechanisms of drought tolerance based on root architecture and lipid composition in wheat are poorly understood. We quantified the differences in root morphological traits and ...phospholipids and galactolipids levels between winter and spring wheat genotypes at variable water supply amounts (drought stress).
Methods
Experiments were conducted using seven winter and four spring wheat (
Triticum aestivum
) genotypes. In the first experiment, solid agar medium was used to quantify seminal root angles. In the second experiment, the plants were grown in 150-cm columns in a greenhouse under full and deficit water supply for 65 days to record root architecture. The root tips (2-cm-long) were used for quantifying polar lipids.
Results
Drought stress at vegetative stage decreased plant height (14%), total dry matter production (48%), maximum root length (25%), root length:shoot length ratio (11%), and other root traits. Winter wheat genotypes had ~1.5 times higher maximum root length than spring wheat genotypes. Significant differences in molar percentages of root phospholipids and galactolipids, molecular species, and double bond index of galactolipids were observed among spring wheat but not winter wheat genotypes.
Conclusions
Based on the genotypes studied, the drought tolerant mechanism of winter wheat was associated with deep root system, and in spring wheat it was well branched (albeit shallow) root system with more unsaturated membrane lipids.
High temperature (HT) decreases seed set percentage in sorghum (Sorghum bicolor L. Moench). The relative sensitivity of pollen and particularly pistil and the mechanistic response that induces ...tolerance or susceptibility to HT are not well known and hence are the major objectives of this research. The male sterile (ATx399) and fertile (RTx430) lines were exposed to 30/20 °C (optimum temperature), 36/26 °C (HT1), and 39/29 °C (HT2) from the start of booting to seed set in a controlled environment. Similarly, in the field, HT stress was imposed using heat tents. HT stress decreased pollen germination. Relatively high levels of reactive oxygen species and decreased antioxidant enzyme activity and phospholipid unsaturation were observed in pollen compared to pistil under HT. The severe cell organelle damage was observed in pollen and pistil at 36/26 and 39/29 °C, respectively. The seed set percentage was higher in HT‐stressed pistil pollinated with optimum‐temperature pollen. Direct and reciprocal crosses indicate that pollen was more sensitive with larger decreases in seed set percentage than pistil under HT stress. The negative impact was greater in pollen than pistil at lower temperatures. Overall, pollen was more sensitive than pistil to HT stress because it is more susceptible to oxidative damage than pistil.
High‐temperature (HT) stress during the booting decreased both pollen and pistil functions compared with optimum temperature (OT) under controlled environments and field conditions. Nonfunctionality of gametes under HT stress was associated with changes in anatomy, phospholipid composition and unsaturation, increased reactive oxygen species, and decreased antioxidant enzyme activity. The various cross combinations indicate that pollen was more sensitive with larger decreases in seed set percentage than pistil under HT stress. The negative impact was greater in pollen than pistil at lower temperatures.
Crop diseases cause the release of volatiles. Here, the use of an SnO2-based chemoresistive sensor for early diagnosis has been attempted. Ionone is one of the signature volatiles released by the ...enzymatic and nonenzymatic cleavage of carotene at the latent stage of some biotic stresses. To our knowledge, this is the first attempt at sensing volatiles with multiple oxidation sites, i.e., ionone (4 oxidation sites), from the phytovolatile library, to derive stronger signals at minimum concentrations. Further, the sensitivity was enhanced on an interdigitated electrode by the addition of platinum as the dopant for a favorable space charge layer and for surface island formation for reactive interface sites. The mechanistic influence of oxygen vacancy formation was studied through detailed density functional theory (DFT) calculations and reactive oxygen-assisted enhanced binding through X-ray photoelectron spectroscopy (XPS) analysis.
Priming of seed is intended to reduce the time to germination through activation of pre-germinative processes. Seed priming is controlled hydration followed by a drying (dehydration) process. The ...physiological processes during hydration (imbibition) were studied in detail in tomato. In contrast, gibberellic acid changes during the dehydration phase were not studied in detail. We hypothesize that there would be a change in the GA concentration during the dehydration phase of the seed priming process, which may influence the vigour characteristics of the resultant seedling. The objective of the study was to understand the influence dehydration phase of seed priming on GA biosynthesis and its subsequent effect on seed germination and seedling traits of tomato. First, the hydroprimed and unprimed seeds were re-imbibed for 3 h, 6 h, 9 h, and 12 h to initiate the germination process, and the GA concentration and seedling vigour associated parameters were recorded. In the second experiment, the imbibed seeds were dehydrated for 3 h, 6 h, 9 h, and 12 h, then re-imbibed for 3 h, 6 h, 9 h, and 12 h to understand the effect of dehydration on the GA concentration and its associated traits. Results revealed that hydroprimed seeds had a higher GA concentration and seedling vigour than unprimed seeds. The seeds that are completely dehydrated for 12 h had the highest GA and seed vigour parameters. Therefore, increased vigour of hydroprimed seeds is due to the higher levels of GA accumulated during the dehydration phase of seed priming, which can improve seed germination and seedling vigour of tomato.
Sorghum Sorghum bicolor (L.) Moench yield is limited by the coincidence of drought during its sensitive stages. The use of cerium oxide nanoparticles in agriculture is minimal despite its antioxidant ...properties. We hypothesize that drought-induced decreases in photosynthetic rate in sorghum may be associated with decreased tissue water content and organelle membrane damage. We aimed to quantify the impact of foliar application of nanoceria on transpiration rate, accumulation of compatible solutes, photosynthetic rate and reproductive success under drought stress in sorghum. In order to ascertain the mechanism by which nanoceria mitigate drought-induced inhibition of photosynthesis and reproductive success, experiments were undertaken in a factorial completely randomized design or split-plot design. Foliar spray of nanoceria under progressive soil drying conserved soil moisture by restricting the transpiration rate than water spray, indicating that nanoceria exerted strong stomatal control. Under drought stress at the seed development stage, foliar application of nanoceria at 25 mg L−1 significantly improved the photosynthetic rate (19%) compared to control by maintaining a higher tissue water content (18%) achieved by accumulating compatible solutes. The nanoceria-sprayed plants exhibited intact chloroplast and thylakoid membranes because of increased heme enzymes catalase (53%) and peroxidase (45%) activity, which helped in the reduction of hydrogen peroxide content (74%). Under drought, compared to water spray, nanoceria improved the seed-set percentage (24%) and individual seed mass (27%), eventually causing a higher seed yield. Thus, foliar application of nanoceria at 25 mg L−1 under drought can increase grain yield through increased photosynthesis and reproductive traits.
•Drought stress decreased the photosynthetic rate through chloroplast membrane damage and yield through decreased seed-set percentage and individual seed mass.•Foliar spray of nanoceria sustained the photosynthetic rate by protecting the thylakoid membrane of chloroplast and mitochondria membranes through reduced reactive oxygen species production and increased antioxidant enzymes activity under drought stress.•Drought stress decreased the tissue water content, and foliar spray of nanoceria increased tissue water content by restricting the transpiration rate and enhanced osmotic adjustment.•Foliar spray of nanoceria at the rate of 25 mg L−1 during post-flowering and anthesis stage drought can increase the grain yield of sorghum.
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