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19 pages, 6222 KiB

Open AccessArticle

Sulla (Hedysarum coronarium L.) Response to Drought Stress during Early Vegetative Stage

by Roberta Rossi, Mariana Amato and Salvatore Claps

Plants 2023, 12(19), 3396; https://doi.org/10.3390/plants12193396 - 26 Sep 2023

Cited by 3 | Viewed by 1476

Abstract

Sulla (Hedysarum coronarium L.) is a Mediterranean biannual anthelmintic forage. Due to its high productivity, nutraceutical value, and suitability for harsh environments, interest in this crop is growing. Under the current scenario of climate change and water scarcity, it is important to [...] Read more.

Sulla (Hedysarum coronarium L.) is a Mediterranean biannual anthelmintic forage. Due to its high productivity, nutraceutical value, and suitability for harsh environments, interest in this crop is growing. Under the current scenario of climate change and water scarcity, it is important to evaluate crop drought tolerance, especially for newly bred materials. Drought stress and well-watered conditions (50 vs. 80% of the field capacity) were applied in a pot experiment to compare responses of the widespread commercial variety Bellante with those of a recently released variety named ‘Centauro’, currently registered in the Italian national register of plant varieties but not yet available on the market. Compared to the well-watered treatment, drought-stressed plants showed lower values of fresh biomass (−69%), number of leaves (−68%), and root length (−49%). The Centauro cv. showed a different architecture to Bellante with more shoots (+43% P < 0.05) and a trend for more leaves (+25% P = 0.08). These traits are possibly related to its superior palatability. Centauro also developed a higher root length (+70%, P < 0.05) across irrigation levels. Drought stress affected condensed tannin (CT) content. A significant genotype × environment interaction was found with Centauro displaying more (+50%) and less (−35%) CT than Bellante under drought stress and well-watered conditions, respectively. The higher constitutive root length density of Centauro may be exploited in breeding programs aimed at improving the root sink, given the role of this trait in resource acquisition capacity and root-derived ecosystem services. Full article

(This article belongs to the Special Issue Responses of Plants to Environmental Stresses Volume II)

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15 pages, 3046 KiB

Open AccessArticle

Physiological Response of Nutrient-Stressed Lemna gibba to Pulse Colloidal Silver Treatment

by Martina Varga, Tanja Žuna Pfeiffer, Lidija Begović, Selma Mlinarić, Janja Horvatić, Tihana Miloloža and Ivna Štolfa Čamagajevac

Plants 2023, 12(6), 1367; https://doi.org/10.3390/plants12061367 - 19 Mar 2023

Viewed by 2261

Abstract

Wastewater is a source of many environmental pollutants and potentially high concentrations of essential plant nutrients. Site-specific nutrient levels may influence the response of exposed plants to a chemical stressor. In the present study, we focused on the responses of model aquatic macrophyte [...] Read more.

Wastewater is a source of many environmental pollutants and potentially high concentrations of essential plant nutrients. Site-specific nutrient levels may influence the response of exposed plants to a chemical stressor. In the present study, we focused on the responses of model aquatic macrophyte swollen duckweed (Lemna gibba L.) to a short pulse exposure and a commercially available colloidal silver product as a potential environmental chemical stressor, combined with two levels of total nitrogen and phosphorus nutrition. Treatment with the commercially available colloidal silver product caused oxidative stress in L. gibba plants under both high and low nutrient levels. Plants grown and treated under high nutrient levels showed lower levels of lipid peroxidation and hydrogen peroxide accumulation, as well as higher levels of photosynthetic pigment content in comparison to treated plants under low nutrient levels. Higher free radical scavenging activity for plants treated with silver in combination with high nutrient levels resulted in better overall protection from silver-induced oxidative stress. The results showed that external nutrient levels significantly affected the L. gibba plant’s response to the colloidal silver presence in the environment and that nutrient levels should be considered in the assessment of potential environmental impact for contaminants. Full article

(This article belongs to the Special Issue Responses of Plants to Environmental Stresses Volume II)

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18 pages, 2971 KiB

Open AccessArticle

Probiotics, Proline and Calcium Induced Protective Responses of Triticum aestivum under Drought Stress

by Rima Mockevičiūtė, Sigita Jurkonienė, Vaidevutis Šveikauskas, Mariam Zareyan, Elžbieta Jankovska-Bortkevič, Jurga Jankauskienė, Liudmyla Kozeko and Virgilija Gavelienė

Plants 2023, 12(6), 1301; https://doi.org/10.3390/plants12061301 - 14 Mar 2023

Cited by 7 | Viewed by 2527

Abstract

In order to increase plants tolerance to drought, the idea of treating them with stress-protecting compounds exogenously is being considered. In this study, we aimed to evaluate and compare the impact of exogenous calcium, proline, and plant probiotics on the response of winter [...] Read more.

In order to increase plants tolerance to drought, the idea of treating them with stress-protecting compounds exogenously is being considered. In this study, we aimed to evaluate and compare the impact of exogenous calcium, proline, and plant probiotics on the response of winter wheat to drought stress. The research was carried out under controlled conditions, simulating a prolonged drought from 6 to 18 days. Seedlings were treated with ProbioHumus 2 µL g⁻¹ for seed priming, 1 mL 100 mL⁻¹ for seedling spraying, and proline 1 mM according to the scheme. 70 g m⁻² CaCO₃ was added to the soil. All tested compounds improved the prolonged drought tolerance of winter wheat. ProbioHumus, ProbioHumus + Ca had the greatest effect on maintaining the relative leaf water content (RWC) and in maintaining growth parameters close to those of irrigated plants. They delayed and reduced the stimulation of ethylene emission in drought-stressed leaves. Seedlings treated with ProbioHumus and ProbioHumus + Ca had a significantly lower degree of membrane damage induced by ROS. Molecular studies of drought-responsive genes revealed substantially lower expression of Ca and Probiotics + Ca treated plants vs. drought control. The results of this study showed that the use of probiotics in combination with Ca can activate defense reactions that can compensate for the adverse effects of drought stress. Full article

(This article belongs to the Special Issue Responses of Plants to Environmental Stresses Volume II)

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19 pages, 3039 KiB

Open AccessEditor’s ChoiceArticle

Light Quality Impacts Vertical Growth Rate, Phytochemical Yield and Cannabinoid Production Efficiency in Cannabis sativa

by Victorio Morello, Vincent Desaulniers Brousseau, Natalie Wu, Bo-Sen Wu, Sarah MacPherson and Mark Lefsrud

Plants 2022, 11(21), 2982; https://doi.org/10.3390/plants11212982 - 4 Nov 2022

Cited by 22 | Viewed by 8267

Abstract

Light is one of the most crucial parameters for enclosed cannabis (Cannabis sativa) production, as it highly influences growth, secondary metabolite production, and operational costs. The objective of this study was to investigate and evaluate the impact of six light spectra [...] Read more.

Light is one of the most crucial parameters for enclosed cannabis (Cannabis sativa) production, as it highly influences growth, secondary metabolite production, and operational costs. The objective of this study was to investigate and evaluate the impact of six light spectra on C. sativa (‘Babbas Erkle Cookies’ accession) growth traits and secondary metabolite (cannabinoid and terpene) profiles. The light spectra evaluated included blue (430 nm), red (630 nm), rose (430 + 630 nm, ratio 1:10), purple (430 + 630 nm, ratio 2:1), and amber (595 nm) LED treatments, in addition to a high-pressure sodium (HPS, amber-rich light) treatment as a control. All the LED light treatments had lower fresh mean inflorescence mass than the control (HPS, 133.59 g plant⁻¹), and monochromatic blue light yielded the least fresh inflorescence mass (76.39 g plant⁻¹). Measurement of Δ9-tetrahydrocannabinol (THC) concentration (%) and total yield (g plant⁻¹) showed how inflorescence mass and THC concentration need to be analyzed conjointly. Blue treatment resulted in the highest THC concentration (10.17% m/m), yet the lowest THC concentration per plant (1.44 g plant⁻¹). The highest THC concentration per plant was achieved with HPS (2.54 g plant⁻¹). As with THC, blue light increased cannabigerol (CBG) and terpene concentration. Conversely, blue light had a lesser impact on cannabidiol (CBD) biosynthesis in this C. sativa chemotype. As the combined effects of the light spectrum on both growth traits and secondary metabolites have important ramifications for the industry, the inappropriate spectral design could cause a reduction in cannabinoid production (20–40%). These findings show promise in helping producers choose spectral designs that meet specific C. sativa production goals. Full article

(This article belongs to the Special Issue Responses of Plants to Environmental Stresses Volume II)

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14 pages, 1292 KiB

Open AccessArticle

Drought-Induced Responses in Maize under Different Vapor Pressure Deficit Conditions

by Mura Jyostna Devi, Vangimalla R. Reddy and Dennis Timlin

Plants 2022, 11(20), 2771; https://doi.org/10.3390/plants11202771 - 19 Oct 2022

Cited by 6 | Viewed by 2585

Abstract

Water stress in plants depends on the soil water level and the evaporative demand. In this study, the physiological, biochemical, and molecular response of maize were examined under three evaporative demand conditions (low—1.00 kPa, medium—2.2 kPa, and high—4.00 kPa Vapor pressure deficit (VPD)) [...] Read more.

Water stress in plants depends on the soil water level and the evaporative demand. In this study, the physiological, biochemical, and molecular response of maize were examined under three evaporative demand conditions (low—1.00 kPa, medium—2.2 kPa, and high—4.00 kPa Vapor pressure deficit (VPD)) at three different soil water content (SWC); well-watered, 45%, and 35% SWC. Plants grown at 35% SWC under high VPD had significant (p < 0.01) lower leaf weight, leaf area, and leaf number than low VPD. Plants under low, medium, and high VPD with drought stress (45% and 35% SWC) showed a 30 to 60% reduction in their leaf area compared to well-watered plants. Gas exchange parameters including photosynthesis, stomatal conductance, and water use efficiency exhibited significant differences (p < 0.01) between treatments, with the highest reduction occuring at 35% SWC and high VPD. Both drought and VPD significantly (p < 0.01) increased C₄ enzyme levels and some transcription factors with increased stress levels. Transcription factors primarily related to Abssisic Acid (ABA) synthesis were upregulated under drought, which might be related to high ABA levels. In summary, severe drought levels coupled with high VPD had shown a significant decrease in plant development by modifying enzymes, ABA, and transcription factors. Full article

(This article belongs to the Special Issue Responses of Plants to Environmental Stresses Volume II)

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18 pages, 3338 KiB

Open AccessArticle

Transcriptomics Using the Enriched Arabidopsis Shoot Apex Reveals Developmental Priming Genes Involved in Plastic Plant Growth under Salt Stress Conditions

by Ok-Kyoung Cha, Soeun Yang and Horim Lee

Plants 2022, 11(19), 2546; https://doi.org/10.3390/plants11192546 - 28 Sep 2022

Cited by 4 | Viewed by 2391

Abstract

In the shoot apical meristem (SAM), the homeostasis of the stem cell population supplying new cells for organ formation is likely a key mechanism of multicellular plant growth and development. As plants are sessile organisms and constantly encounter environmental abiotic stresses, postembryonic development [...] Read more.

In the shoot apical meristem (SAM), the homeostasis of the stem cell population supplying new cells for organ formation is likely a key mechanism of multicellular plant growth and development. As plants are sessile organisms and constantly encounter environmental abiotic stresses, postembryonic development from the shoot stem cell population must be considered with surrounding abiotic stresses for plant adaptation. However, the underlying molecular mechanisms for plant adaptation remain unclear. Previous studies found that the stem-cell-related mutant clv3-2 has the property of salt tolerance without the differential response of typical stress-responsive genes compared to those in WT Ler. Based on these facts, we hypothesized that shoot meristems contain developmental priming genes having comprehensively converged functions involved in abiotic stress response and development. To better understand the biological process of developmental priming genes in the SAM, we performed RNA sequencing (RNA-seq) and transcriptome analysis through comparing genome-wide gene expression profiles between enriched shoot apex and leaf tissues. As a result, 121 putative developmental priming genes differentially expressed in the shoot apex compared to the leaf were identified under normal and salt stress conditions. RNA-seq experiments also revealed the shoot apex-specific responsive genes for salt stress conditions. Based on combinatorial comparisons, 19 developmental priming genes were finally identified, including developmental genes related to cell division and abiotic/biotic-stress-responsive genes. Moreover, some priming genes showed CLV3-dependent responses under salt stress conditions in the clv3-2. These results presumably provide insight into how shoot meristem tissues have relatively high viability against stressful environmental conditions for the developmental plasticity of plants. Full article

(This article belongs to the Special Issue Responses of Plants to Environmental Stresses Volume II)

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18 pages, 4047 KiB

Open AccessArticle

Isolation and Characterization of a Novel Pathogenesis-Related Protein-1 Gene (AvPR-1) with Induced Expression in Oat (Avena sativa L.) during Abiotic and Hormonal Stresses

by Khalid A. AlHudaib, Naimah Asid Alanazi, Mouna Ghorbel, Sherif Mohamed El-Ganainy and Faiçal Brini

Plants 2022, 11(17), 2284; https://doi.org/10.3390/plants11172284 - 31 Aug 2022

Cited by 9 | Viewed by 2103

Abstract

Pathogenesis-related protein-1 (PR-1) plays crucial roles in regulating plant responses to biotic and abiotic stresses. This study aimed to isolate and characterize the first PR-1 (AvPR-1) gene in oat (Avena sativa L.). AvPR-1 presented conserved signal peptide motifs and core amino acid [...] Read more.

Pathogenesis-related protein-1 (PR-1) plays crucial roles in regulating plant responses to biotic and abiotic stresses. This study aimed to isolate and characterize the first PR-1 (AvPR-1) gene in oat (Avena sativa L.). AvPR-1 presented conserved signal peptide motifs and core amino acid composition in the functional protein domains as the protein sequence of AvPR-1 presented 98.28%, 97.7%, and 95.4% identity with known PR1 proteins isolated from Triticum aestivum PRB1-2-like, Triticum dicoccoides PRB1-2-like, and Aegilops tauschii subsp. tauschii, respectively. Bioinformatic analysis showed that the AvPR-1 protein belongs to the CAP superfamily (PF00188). Secondary and 3D structure analyses of the AvPR-1 protein were also conducted, confirming sequence conservation of PR-1 among studied species. The AvPR-1 protein harbors a calmodulin-binding domain located in its C-terminal part as previously shown for its wheat homolog TdPR1.2. Moreover, gene expression analysis showed that AvPR-1 was induced in response to many abiotic and hormonal stresses especially in leaves after treatment for 48 h. This is the first study exhibiting the expression profiles of the AvPR-1 gene under different stresses in oat. Full article

(This article belongs to the Special Issue Responses of Plants to Environmental Stresses Volume II)

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25 pages, 2093 KiB

Open AccessArticle

Improving Yield Components and Desirable Eating Quality of Two Wheat Genotypes Using Si and NanoSi Particles under Heat Stress

by Nesma M. Helal, Hemmat I. Khattab, Manal M. Emam, Gniewko Niedbała, Tomasz Wojciechowski, Inès Hammami, Nadiyah M. Alabdallah, Doaa Bahaa Eldin Darwish, Mohamed M. El-Mogy and Heba M. Hassan

Plants 2022, 11(14), 1819; https://doi.org/10.3390/plants11141819 - 11 Jul 2022

Cited by 21 | Viewed by 3353 | Correction

Abstract

Global climate change is a significant challenge that will significantly lower crop yield and staple grain quality. The present investigation was conducted to assess the effects of the foliar application of either Si (1.5 mM) or Si nanoparticles (1.66 mM) on the yield [...] Read more.

Global climate change is a significant challenge that will significantly lower crop yield and staple grain quality. The present investigation was conducted to assess the effects of the foliar application of either Si (1.5 mM) or Si nanoparticles (1.66 mM) on the yield and grain quality attributes of two wheat genotypes (Triticum aestivum L.), cv. Shandweel 1 and cv. Gemmeiza 9, planted at normal sowing date and late sowing date (heat stress). Si and Si nanoparticles markedly mitigated the observed decline in yield and reduced the heat stress intensity index value at late sowing dates, and improved yield quality via the decreased level of protein, particularly glutenin, as well as the lowered activity of α-amylase in wheat grains, which is considered a step in improving grain quality. Moreover, Si and nanoSi significantly increased the oil absorption capacity (OAC) of the flour of stressed wheat grains. In addition, both silicon and nanosilicon provoked an increase in cellulose, pectin, total phenols, flavonoid, oxalic acid, total antioxidant power, starch and soluble protein contents, as well as Ca and K levels, in heat-stressed wheat straw, concomitant with a decrease in lignin and phytic acid contents. In conclusion, the pronounced positive effects associated with improving yield quantity and quality were observed in stressed Si-treated wheat compared with Si nanoparticle-treated ones, particularly in cv. Gemmeiza 9. Full article

(This article belongs to the Special Issue Responses of Plants to Environmental Stresses Volume II)

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15 pages, 5007 KiB

Open AccessEditor’s ChoiceArticle

Characteristics of Sunburn Browning Fruit and Rootstock-Dependent Damage-Free Yield of Ambrosia™ Apple after Sustained Summer Heat Events

by Hao Xu, Yoichiro Watanabe, Danielle Ediger, Xiaotang Yang and Davis Iritani

Plants 2022, 11(9), 1201; https://doi.org/10.3390/plants11091201 - 29 Apr 2022

Cited by 8 | Viewed by 3338

Abstract

The 2021 summer heat waves experienced in the Pacific Northwest led to considerable fruit damage in many apple production zones. Sunburn browning (SB) was a particularly evident symptom. To understand the mechanism underlying the damage and to facilitate the early assessment of compromised [...] Read more.

The 2021 summer heat waves experienced in the Pacific Northwest led to considerable fruit damage in many apple production zones. Sunburn browning (SB) was a particularly evident symptom. To understand the mechanism underlying the damage and to facilitate the early assessment of compromised fruit quality, we conducted a study on external characteristics and internal quality attributes of SB ‘Ambrosia’ apple (Malus domestica var. Ambrosia) and evaluated the fruit loss on five rootstocks. The cell integrity of the epidermal and hypodermal layers of fruit skins in the SB patch was compromised. Specifically, the number of chloroplasts and anthocyanin decreased in damaged cells, while autofluorescent stress-related compounds accumulated in dead cells. Consequently, the affected sun-exposed skin demonstrated a significant increase in differential absorbance between 670 nm and 720 nm, measured using a handheld apple DA meter, highlighting the potential of using this method as a non-destructive early indicator for sunburn damage. Sunburn browning eventually led to lower fruit weight, an increase in average dry matter content, soluble solids content, acidity, deteriorated weight retention, quicker loss of firmness, and accelerated ethylene emission during ripening. Significant inconsistency was found between the sun-exposed and shaded sides in SB apples regarding dry matter content, firmness, and tissue water potential, which implied preharvest water deficit in damaged tissues and the risk of quicker decline of postharvest quality. Geneva 935 (G.935), a large-dwarfing rootstock with more vigor and higher water transport capacity, led to a lower ratio of heat-damaged fruits and a higher yield of disorder-free fruits, suggesting rootstock selection as a long-term horticultural measure to mitigate summer heat stress. Full article

(This article belongs to the Special Issue Responses of Plants to Environmental Stresses Volume II)

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22 pages, 18232 KiB

Open AccessEditor’s ChoiceArticle

The Photosynthetic Efficiency and Carbohydrates Responses of Six Edamame (Glycine max. L. Merrill) Cultivars under Drought Stress

by Jeremiah M. Hlahla, Mpho S. Mafa, Rouxléne van der Merwe, Orbett Alexander, Mart-Mari Duvenhage, Gabre Kemp and Makoena J. Moloi

Plants 2022, 11(3), 394; https://doi.org/10.3390/plants11030394 - 31 Jan 2022

Cited by 25 | Viewed by 4779

Abstract

Vegetable-type soybean, also known as edamame, was recently introduced to South Africa. However, there is lack of information on its responses to drought. The aim of this study was to investigate the photosynthetic efficiency and carbohydrates responses of six edamame cultivars under drought [...] Read more.

Vegetable-type soybean, also known as edamame, was recently introduced to South Africa. However, there is lack of information on its responses to drought. The aim of this study was to investigate the photosynthetic efficiency and carbohydrates responses of six edamame cultivars under drought stress. Photosynthetic efficiency parameters, including chlorophyll fluorescence and stomatal conductance, were determined using non-invasive methods, while pigments were quantified spectrophotometrically. Non-structural carbohydrates were quantified using Megazyme kits. Structural carbohydrates were determined using Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Drought stress significantly increased the Fv/Fm and PIabs of AGS429 and UVE17 at pod filling stage. Chlorophyll-a, which was most sensitive to drought, was significantly reduced in AGS429 and UVE17, but chlorophyll-b was relatively stable in all cultivars, except UVE17, which showed a significant decline at flowering stage. AGS354 and AGS429 also showed reduced chlorophyll-b at pod filling. UVE17 showed a significant reduction in carotenoid content and a substantial reduction in stomatal conductance during pod filling. Drought stress during pod filling resulted in a significant increase in the contents of trehalose, sucrose and starch, but glucose was decreased. Chlorophyll-a positively correlated with starch. The FTIR and XRD results suggest that the cell wall of UVE14, followed by UVE8 and AGS429, was the most intact during drought stress. It was concluded that carotenoids, stomatal conductance, starch and hemicellulose could be used as physiological/biochemical indicators of drought tolerance in edamame. This information expands our knowledge of the drought defense responses in edamame, and it is essential for the physiological and biochemical screening of drought tolerance. Full article

(This article belongs to the Special Issue Responses of Plants to Environmental Stresses Volume II)

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9 pages, 4836 KiB

Open AccessCommunication

Hourly Relationship between Reference Evapotranspiration and Shoot Shrinkage in Walnut Trees and Pomegranate under Deficit Irrigation

by Eduardo Salgado, Nieggiorba Livellara, Esteban Chaigneau, Fernando Varas and Italo F. Cuneo

Plants 2022, 11(1), 31; https://doi.org/10.3390/plants11010031 - 23 Dec 2021

Viewed by 2403

Abstract

Diameter fluctuations of branches, shoots, or fruits are related to plant transpiration and water potential. In the past, several models have related dendrometric variables and evapotranspiration on a daily scale. However, trunk–branch shrinkage occurs only between dawn and midday, while evapotranspiration occurs most [...] Read more.

Diameter fluctuations of branches, shoots, or fruits are related to plant transpiration and water potential. In the past, several models have related dendrometric variables and evapotranspiration on a daily scale. However, trunk–branch shrinkage occurs only between dawn and midday, while evapotranspiration occurs most of the day from sunrise to sunset. Previous models have failed to incorporate this key fact. The objective of the present study was to assess the relationship of hourly daily shrinkage (HDS) between dawn and the next 4 h to the hourly reference evapotranspiration (EToh) of the same period in walnut trees and pomegranate plants under different irrigation regimes. Our data show that the relationship between EToh and HDS is much better than several previous models that included maximum daily shrinkage (MDS) and reference evapotranspiration (ETo). The novel slope analysis of the relationship between HDS versus time used here corresponds to the velocity at which the HDS occurs, which depends on the ETo intensity at that moment. This new method of analyzing this type of data calls for a revision of these models and sets a new baseline for future analysis. Full article

(This article belongs to the Special Issue Responses of Plants to Environmental Stresses Volume II)

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15 pages, 3211 KiB

Open AccessArticle

Different Drought-Tolerant Mechanisms in Quinoa (Chenopodium quinoa Willd.) and Djulis (Chenopodium formosanum Koidz.) Based on Physiological Analysis

by Pin-Hua Lin and Yun-Yang Chao

Plants 2021, 10(11), 2279; https://doi.org/10.3390/plants10112279 - 24 Oct 2021

Cited by 23 | Viewed by 3495

Abstract

The purpose of this experiment is to study the effects of treatment with 90% (28.5% volumetric water content (VWC)), 75% (24% VWC), 50% (16% VWC), and 25% (8% VWC) of water requirements on the growth of two djulis (Chenopodium formosana Koidz) varieties [...] Read more.

The purpose of this experiment is to study the effects of treatment with 90% (28.5% volumetric water content (VWC)), 75% (24% VWC), 50% (16% VWC), and 25% (8% VWC) of water requirements on the growth of two djulis (Chenopodium formosana Koidz) varieties (red: RP and yellow: OR) and one quinoa (Chenopodium quinoa Willd) varieties (PI). The results showed that drought stress (8% VWC) significantly reduced plant growth and relative water content, and increased H₂O₂ and MDA content in C. formosana and C. quinoa. The most significant increase in these parameters was detected in the OR variety. The antioxidant enzymes, such as SOD, APX, and GR activities of PI variety under drought treatment (8% VWC), are significantly increased, while GR activity of C. formosana also increased significantly. Additionally, C. formosana and PI variety remained at a stable AsA/DHA ratio, but the GSH/GSSG ratio decreased during drought treatment. Moreover, drought stress increased total soluble sugars and proline content in the PI variety. However, C. formosana proline content was extremely significantly enhanced, and only the OR variety increased the total soluble sugar content at the same time during the vegetative growth period. In summary, C. formosana and C. quinoa have different drought tolerance mechanisms to adapt to being cultivated and produced under severe drought conditions. Full article

(This article belongs to the Special Issue Responses of Plants to Environmental Stresses Volume II)

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14 pages, 422 KiB

Open AccessArticle

Changes in Antioxidative Compounds and Enzymes in Small-Leaved Linden (Tilia cordata Mill.) in Response to Mistletoe (Viscum album L.) Infestation

by Liubov Skrypnik, Pavel Maslennikov, Pavel Feduraev, Artem Pungin and Nikolay Belov

Plants 2021, 10(9), 1871; https://doi.org/10.3390/plants10091871 - 10 Sep 2021

Cited by 5 | Viewed by 2287

Abstract

Mistletoe infestation leads to a decrease in the growth of woody plants, their longevity, and partial or complete drying of the top, as well as premature death. Various environmental stress factors, both abiotic and biotic, stimulate the formation of reactive oxygen species and [...] Read more.

Mistletoe infestation leads to a decrease in the growth of woody plants, their longevity, and partial or complete drying of the top, as well as premature death. Various environmental stress factors, both abiotic and biotic, stimulate the formation of reactive oxygen species and the development of oxidative stress in plant tissues. This study aimed to investigate the effect of mistletoe (Viscum album L.) infestation on the response of the antioxidative defense system in leaves of small-leaved linden (Tilia cordata Mill.). Leaves from infested trees were taken from branches (i) without mistletoe, (ii) with 1–2 mistletoe bushes (low degree of infestation), and (iii) with 5–7 mistletoe bushes (high degree of infestation). The relative water content and the chlorophyll a and b contents in leaves from linden branches affected by mistletoe were significantly lower than those in leaves from non-infested trees and from host-tree branches with no mistletoe. At the same time, leaves from branches with low and high degrees of infestation had significantly higher electrolyte leakage, malondialdehyde and hydrogen peroxide content, oxidized forms of ascorbic acid (dehydroascorbic and 2,3-diketogulonic acids), and oxidized glutathione. The results of principal component analysis show that the development of oxidative stress was accompanied by an increase in proline content and in superoxide dismutase, ascorbate peroxidase, glutathione peroxidase, and glutathione reductase activity. Several biochemical parameters (proline, ascorbic acid, dehydroascorbic acid, glutathione, glutathione peroxidase, ascorbate peroxidase, and dehydroascorbate reductase) were found to be altered in leaves from host-tree branches with no mistletoe. This result indicates that the mistletoe infestation of trees not only causes local changes in the locations of hemiparasite attachment, but also affects the redox metabolism in leaves from other parts of the infested tree. Full article

(This article belongs to the Special Issue Responses of Plants to Environmental Stresses Volume II)

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17 pages, 1542 KiB

Open AccessArticle

Effects of Charcoal Rot on Soybean Seed Composition in Soybean Genotypes That Differ in Charcoal Rot Resistance under Irrigated and Non-Irrigated Conditions

by Nacer Bellaloui, Alemu Mengistu, James R. Smith, Hamed K. Abbas, Cesare Accinelli and W. Thomas Shier

Plants 2021, 10(9), 1801; https://doi.org/10.3390/plants10091801 - 29 Aug 2021

Cited by 9 | Viewed by 2708

Abstract

Charcoal rot is a major disease of soybean (Glycine max) caused by Macrophomina phaseolina and results in significant loss in yield and seed quality. The effects of charcoal rot on seed composition (seed protein, oil, and fatty acids), a component of [...] Read more.

Charcoal rot is a major disease of soybean (Glycine max) caused by Macrophomina phaseolina and results in significant loss in yield and seed quality. The effects of charcoal rot on seed composition (seed protein, oil, and fatty acids), a component of seed quality, is not well understood. Therefore, the objective of this research was to investigate the impact of charcoal rot on seed protein, oil, and fatty acids in different soybean genotypes differing in their charcoal rot susceptibility under irrigated and non-irrigated conditions. Two field experiments were conducted in 2012 and 2013 in Jackson, TN, USA. Thirteen genotypes differing in charcoal rot resistance (moderately resistant and susceptible) were evaluated. Under non-irrigated conditions, moderately resistant genotypes showed either no change or increased protein and oleic acid but had lower linolenic acid. Under non-irrigated conditions, most of the susceptible genotypes showed lower protein and linolenic acid but higher oleic acid. Most of the moderately resistant genotypes had higher protein than susceptible genotypes under irrigated and non-irrigated conditions but lower oil than susceptible genotypes. The different responses among genotypes for protein, oil, oleic acid, and linolenic acid observed in each year may be due to both genotype tolerance to drought and environmental conditions, especially heat differences in each year (2012 was warmer than 2013). This research showed that the increases in protein and oleic acid and the decrease in linolenic acid may be a possible physiological mechanism underlying the plant’s responses to the charcoal rot infection. This research further helps scientists understand the impact of irrigated and non-irrigated conditions on seed nutrition changes, using resistant and susceptible genotypes. Full article

(This article belongs to the Special Issue Responses of Plants to Environmental Stresses Volume II)

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13 pages, 2468 KiB

Open AccessArticle

Altering Nitrogen Sources Affects Growth Carbon Costs in Vachellia nilotica Growing in Nutrient-Deficient Grassland Soils

by Nonkululeko Sithole, Zivanai Tsvuura, Kevin Kirkman and Anathi Magadlela

Plants 2021, 10(9), 1762; https://doi.org/10.3390/plants10091762 - 25 Aug 2021

Cited by 3 | Viewed by 2565

Abstract

Vachellianilotica (L.) Willd. Ex Del. is a multipurpose leguminous tree that is common in grassland and savanna ecosystems in southern and eastern Africa. These ecosystem soils are reported to be acidic and nutrient-limited, specifically with regards to nitrogen (N) and phosphorus (P). [...] Read more.

Vachellianilotica (L.) Willd. Ex Del. is a multipurpose leguminous tree that is common in grassland and savanna ecosystems in southern and eastern Africa. These ecosystem soils are reported to be acidic and nutrient-limited, specifically with regards to nitrogen (N) and phosphorus (P). The presence of this plant in these terrestrial ecosystems improves soil fertility benefiting the surrounding vegetation due to its ability to fix atmospheric N. This study seeks to understand the N-fixing bacteria symbiosis and physiological adaptations of V. nilotica in these acidic and nutrient-deficient KwaZulu-Natal soils. The soils used for this study were collected from the Ukulinga Grassland Nutrient Experiment located at the Ukulinga research farm of the University of KwaZulu-Natal, Pietermaritzburg, South Africa. Due to long-term soil nutrient addition treatments, these soils offered a diverse nutrient variation for better understanding the effects of acidity and nutrient variation on microbial symbiosis, plant nutrition, and biomass accumulation of V. nilotica. V. nilotica was able to maintain growth by relying on both atmospheric and soil-derived N across all treatments decreasing carbon (C) growth costs. There was an increased reliance on atmospheric-derived N of un-nodulated high N-treated plants. The plants grown in high N + P soils were able to nodulate with various species from the Mesorhizobium genus, which resulted in increased biomass compared to other plants. The results of this study show that V. nilotica can alter N sources to reduce C growth costs. In addition, both nodulating and free-living soil N₂ fixing bacteria such as Caulobacter rhizosphaerae, Sphingomonas sp. and Burkholderia contaminans identified in the experimental soils may play an important role under P-deficient conditions. Full article

(This article belongs to the Special Issue Responses of Plants to Environmental Stresses Volume II)

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13 pages, 6032 KiB

Open AccessArticle

Bread Wheat (Triticum aestivum) Responses to Arbuscular Mycorrhizae Inoculation under Drought Stress Conditions

by Neila Abdi, Angeline van Biljon, Chrisna Steyn and Maryke Tine Labuschagne

Plants 2021, 10(9), 1756; https://doi.org/10.3390/plants10091756 - 24 Aug 2021

Cited by 10 | Viewed by 2779

Abstract

Abiotic constraints such as water deficit reduce cereal production. Plants have different strategies against these stresses to improve plant growth, physiological metabolism and crop production. For example, arbuscular mycorrhiza (AM)—bread wheat association has been shown to improve tolerance to drought stress conditions. The [...] Read more.

Abiotic constraints such as water deficit reduce cereal production. Plants have different strategies against these stresses to improve plant growth, physiological metabolism and crop production. For example, arbuscular mycorrhiza (AM)—bread wheat association has been shown to improve tolerance to drought stress conditions. The objective of this study was to determine the effect of AM inoculation on plant characteristics, lipid peroxidation, solute accumulation, water deficit saturation, photosynthetic activity, total phenol secretion and enzymatic activities including peroxidise (PO) and polyphenol oxidase (PPO) in two bread wheat cultivars (PAN3497 and SST806) under well-watered and drought-stressed conditions in plants grown under greenhouse conditions, to determine whether AM can enhance drought tolerance in wheat. AM inoculation improved morphological and physiological parameters in plants under stress. The leaf number increased by 35% and 5%, tiller number by 25% and 23%, chlorophyll content by 7% and 10%, accumulation of soluble sugars by 33% and 14%, electrolyte leakage by 26% and 32%, PPO by 44% and 47% and PO by 30% and 37% respectively, in PAN3497 and SST806, respectively. However, drought stress decreased proline content by 20% and 24%, oxidative damage to lipids measured as malondialdehyde by 34% and 60%, and total phenol content by 55% and 40% respectively, in AM treated plants of PAN3497 and SST806. PAN3497 was generally more drought-sensitive than SST806. This study showed that AM can contribute to protect plants against drought stress by alleviating water deficit induced oxidative stress. Full article

(This article belongs to the Special Issue Responses of Plants to Environmental Stresses Volume II)

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17 pages, 2599 KiB

Open AccessArticle

The Exocytosis Associated SNAP25-Type Protein, SlSNAP33, Increases Salt Stress Tolerance by Modulating Endocytosis in Tomato

by Josselyn Salinas-Cornejo, José Madrid-Espinoza, Isabel Verdugo, Jorge Pérez-Díaz, Alex San Martín-Davison, Lorena Norambuena and Simón Ruiz-Lara

Plants 2021, 10(7), 1322; https://doi.org/10.3390/plants10071322 - 29 Jun 2021

Cited by 7 | Viewed by 3458

Abstract

In plants, vesicular trafficking is crucial for the response and survival to environmental challenges. The active trafficking of vesicles is essential to maintain cell homeostasis during salt stress. Soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) are regulatory proteins of vesicular trafficking. They mediate [...] Read more.

In plants, vesicular trafficking is crucial for the response and survival to environmental challenges. The active trafficking of vesicles is essential to maintain cell homeostasis during salt stress. Soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) are regulatory proteins of vesicular trafficking. They mediate membrane fusion and guarantee cargo delivery to the correct cellular compartments. SNAREs from the Qbc subfamily are the best-characterized plasma membrane SNAREs, where they control exocytosis during cell division and defense response. The Solanum lycopersicum gene SlSNAP33.2 encodes a Qbc-SNARE protein and is induced under salt stress conditions. SlSNAP33.2 localizes on the plasma membrane of root cells of Arabidopsis thaliana. In order to study its role in endocytosis and salt stress response, we overexpressed the SlSNAP33.2 cDNA in a tomato cultivar. Constitutive overexpression promoted endocytosis along with the accumulation of sodium (Na⁺) in the vacuoles. It also protected the plant from cell damage by decreasing the accumulation of hydrogen peroxide (H₂O₂) in the cytoplasm of stressed root cells. Subsequently, the higher level of SlSNAP33.2 conferred tolerance to salt stress in tomato plants. The analysis of physiological and biochemical parameters such as relative water content, the efficiency of the photosystem II, performance index, chlorophyll, and MDA contents showed that tomato plants overexpressing SlSNAP33.2 displayed a better performance under salt stress than wild type plants. These results reveal a role for SlSNAP33.2 in the endocytosis pathway involved in plant response to salt stress. This research shows that SlSNAP33.2 can be an effective tool for the genetic improvement of crop plants. Full article

(This article belongs to the Special Issue Responses of Plants to Environmental Stresses Volume II)

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12 pages, 2944 KiB

Open AccessFeature PaperArticle

Arabidopsis CCoAOMT1 Plays a Role in Drought Stress Response via ROS- and ABA-Dependent Manners

by Hyun Jin Chun, Lack Hyeon Lim, Mi Sun Cheong, Dongwon Baek, Mi Suk Park, Hyun Min Cho, Su Hyeon Lee, Byung Jun Jin, Dong Hyeon No, Ye Jin Cha, Yong Bok Lee, Jong Chan Hong, Dae-Jin Yun and Min Chul Kim

Plants 2021, 10(5), 831; https://doi.org/10.3390/plants10050831 - 21 Apr 2021

Cited by 24 | Viewed by 3670

Abstract

Plants possess adaptive reprogramed modules to prolonged environmental stresses, including adjustment of metabolism and gene expression for physiological and morphological adaptation. CCoAOMT1 encodes a caffeoyl CoA O-methyltransferase and is known to play an important role in adaptation of Arabidopsis plants to prolonged saline [...] Read more.

Plants possess adaptive reprogramed modules to prolonged environmental stresses, including adjustment of metabolism and gene expression for physiological and morphological adaptation. CCoAOMT1 encodes a caffeoyl CoA O-methyltransferase and is known to play an important role in adaptation of Arabidopsis plants to prolonged saline stress. In this study, we showed that the CCoAOMT1 gene plays a role in drought stress response. Transcript of CCoAOMT1 was induced by salt, dehydration (drought), and methyl viologen (MV), and loss of function mutants of CCoAOMT1, ccoaomt1-1, and ccoaomt1-2 exhibit hypersensitive phenotypes to drought and MV stresses. The ccoaomt1 mutants accumulated higher level of H₂O₂ in the leaves and expressed lower levels of drought-responsive genes including RD29B, RD20, RD29A, and ERD1, as well as ABA3 3 and NCED3 encoding ABA biosynthesis enzymes during drought stress compared to wild-type plants. A seed germination assay of ccoaomt1 mutants in the presence of ABA also revealed that CCoAOMT1 functions in ABA response. Our data suggests that CCoAOMT1 plays a positive role in response to drought stress response by regulating H₂O₂ accumulation and ABA signaling. Full article

(This article belongs to the Special Issue Responses of Plants to Environmental Stresses Volume II)

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26 pages, 1216 KiB

Open AccessEditor’s ChoiceReview

The Contribution of PGPR in Salt Stress Tolerance in Crops: Unravelling the Molecular Mechanisms of Cross-Talk between Plant and Bacteria

by Gianluigi Giannelli, Silvia Potestio and Giovanna Visioli

Plants 2023, 12(11), 2197; https://doi.org/10.3390/plants12112197 - 1 Jun 2023

Cited by 27 | Viewed by 5861

Abstract

Soil salinity is a major abiotic stress in global agricultural productivity with an estimated 50% of arable land predicted to become salinized by 2050. Since most domesticated crops are glycophytes, they cannot be cultivated on salt soils. The use of beneficial microorganisms inhabiting [...] Read more.

Soil salinity is a major abiotic stress in global agricultural productivity with an estimated 50% of arable land predicted to become salinized by 2050. Since most domesticated crops are glycophytes, they cannot be cultivated on salt soils. The use of beneficial microorganisms inhabiting the rhizosphere (PGPR) is a promising tool to alleviate salt stress in various crops and represents a strategy to increase agricultural productivity in salt soils. Increasing evidence underlines that PGPR affect plant physiological, biochemical, and molecular responses to salt stress. The mechanisms behind these phenomena include osmotic adjustment, modulation of the plant antioxidant system, ion homeostasis, modulation of the phytohormonal balance, increase in nutrient uptake, and the formation of biofilms. This review focuses on the recent literature regarding the molecular mechanisms that PGPR use to improve plant growth under salinity. In addition, very recent -OMICs approaches were reported, dissecting the role of PGPR in modulating plant genomes and epigenomes, opening up the possibility of combining the high genetic variations of plants with the action of PGPR for the selection of useful plant traits to cope with salt stress conditions. Full article

(This article belongs to the Special Issue Responses of Plants to Environmental Stresses Volume II)

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16 pages, 1820 KiB

Open AccessEditor’s ChoiceReview

Epitranscriptomics: An Additional Regulatory Layer in Plants’ Development and Stress Response

by Yasira Shoaib, Babar Usman, Hunseung Kang and Ki-Hong Jung

Plants 2022, 11(8), 1033; https://doi.org/10.3390/plants11081033 - 11 Apr 2022

Cited by 9 | Viewed by 4379

Abstract

Epitranscriptomics has added a new layer of regulatory machinery to eukaryotes, and the advancement of sequencing technology has revealed more than 170 post-transcriptional modifications in various types of RNAs, including messenger RNA (mRNA), transfer RNA (tRNA), ribosomal RNA (rRNA), and long non-coding RNA [...] Read more.

Epitranscriptomics has added a new layer of regulatory machinery to eukaryotes, and the advancement of sequencing technology has revealed more than 170 post-transcriptional modifications in various types of RNAs, including messenger RNA (mRNA), transfer RNA (tRNA), ribosomal RNA (rRNA), and long non-coding RNA (lncRNA). Among these, N6-methyladenosine (m⁶A) and N5-methylcytidine (m⁵C) are the most prevalent internal mRNA modifications. These regulate various aspects of RNA metabolism, mainly mRNA degradation and translation. Recent advances have shown that regulation of RNA fate mediated by these epitranscriptomic marks has pervasive effects on a plant’s development and responses to various biotic and abiotic stresses. Recently, it was demonstrated that the removal of human-FTO-mediated m⁶A from transcripts in transgenic rice and potatoes caused a dramatic increase in their yield, and that the m⁶A reader protein mediates stress responses in wheat and apple, indicating that regulation of m⁶A levels could be an efficient strategy for crop improvement. However, changing the overall m⁶A levels might have unpredictable effects; therefore, the identification of precise m⁶A levels at a single-base resolution is essential. In this review, we emphasize the roles of epitranscriptomic modifications in modulating molecular, physiological, and stress responses in plants, and provide an outlook on epitranscriptome engineering as a promising tool to ensure food security by editing specific m⁶A and m⁵C sites through robust genome-editing technology. Full article

(This article belongs to the Special Issue Responses of Plants to Environmental Stresses Volume II)

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Jump to: Research, Review

1 pages, 1124 KiB

Open AccessCorrection

Correction: Helal et al. Improving Yield Components and Desirable Eating Quality of Two Wheat Genotypes Using Si and NanoSi Particles under Heat Stress. Plants 2022, 11, 1819

by Nesma M. Helal, Hemmat I. Khattab, Manal M. Emam, Gniewko Niedbała, Tomasz Wojciechowski, Inès Hammami, Nadiyah M. Alabdallah, Doaa Bahaa Eldin Darwish, Mohamed M. El-Mogy and Heba M. Hassan

Plants 2023, 12(14), 2637; https://doi.org/10.3390/plants12142637 - 13 Jul 2023

Viewed by 696

Abstract

In the original publication [...] Full article

(This article belongs to the Special Issue Responses of Plants to Environmental Stresses Volume II)

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