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Water, a necessary component of cell protoplasm, plays an essential role in supporting life on Earth; nevertheless, extreme changes in climatic conditions limit water availability, causing numerous issues, such as the current water-scarce regimes in many regions of the biome. This review aims to collect data from various published studies in the literature to understand and critically analyze plants’ morphological, growth, yield, and physio-biochemical responses to drought stress and their potential to modulate and nullify the damaging effects of drought stress via activating natural physiological and biochemical mechanisms. In addition, the review described current breakthroughs in understanding how plant hormones influence drought stress responses and phytohormonal interaction through signaling under water stress regimes. The information for this review was systematically gathered from different global search engines and the scientific literature databases Science Direct, including Google Scholar, Web of Science, related studies, published books, and articles. Drought stress is a significant obstacle to meeting food demand for the world’s constantly growing population. Plants cope with stress regimes through changes to cellular osmotic potential, water potential, and activation of natural defense systems in the form of antioxidant enzymes and accumulation of osmolytes including proteins, proline, glycine betaine, phenolic compounds, and soluble sugars. Phytohormones modulate developmental processes and signaling networks, which aid in acclimating plants to biotic and abiotic challenges and, consequently, their survival. Significant progress has been made for jasmonates, salicylic acid, and ethylene in identifying important components and understanding their roles in plant responses to abiotic stress. Other plant hormones, such as abscisic acid, auxin, gibberellic acid, brassinosteroids, and peptide hormones, have been linked to plant defense signaling pathways in various ways.

Chromium (Cr) is a toxic heavy metal that contaminates soil and water resources after its discharge from different industries. A pot experiment was conducted to determine the effects of single and/or combined application of sodium nitroprusside (SNP) (250 μM) and sodium hydrogen sulfide (NaHS) (1 mM) on growth, photosynthetic pigments, gas exchange characteristics, oxidative stress biomarkers, antioxidant machinery (enzymatic and non-enzymatic antioxidants), ion uptake, organic acid exudation, and Cr uptake of spinach ( Spinacia oleracea L.) exposed to severe Cr stress [Cr: 0 (no Cr), 150, and 300 μM]. Our results depicted that Cr addition to the soil significantly ( P < 0.05) decreased plant growth and biomass, gas exchange attributes, and mineral uptake by S . oleracea when compared to the plants grown without the addition of Cr. However, Cr toxicity boosted the production of reactive oxygen species (ROS) by increasing the content of malondialdehyde (MDA), which is the indication of oxidative stress in S . oleracea , and was also manifested by hydrogen peroxide (H 2 O 2 ) content and electrolyte leakage to the membrane-bound organelles. The results showed that the activities of various antioxidative enzymes, such as superoxidase dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX), and the content of non-enzymatic antioxidants, such as phenolic, flavonoid, ascorbic acid, and anthocyanin, initially increased with an increase in the Cr concentration in the soil. The results also revealed that the levels of soluble sugar, reducing sugar, and non-reducing sugar were decreased in plants grown under elevating Cr levels, but the accumulation of the metal in the roots and shoots of S . oleracea , was found to be increased, and the values of bioaccumulation factor were <1 in all the Cr treatments. The negative impacts of Cr injury were reduced by the application of SNP and NaHS (individually or combined), which increased plant growth and biomass, improved photosynthetic apparatus, antioxidant enzymes, and mineral uptake, as well as diminished the exudation of organic acids and oxidative stress indicators in roots of S . oleracea by decreasing Cr toxicity. Here, we conclude that the application of SNP and NaHS under the exposure to Cr stress significantly improved plant growth and biomass, photosynthetic pigments, and gas exchange characteristics; regulated antioxidant defense system and essential nutrient uptake; and balanced organic acid exudation pattern in S . oleracea .

In the current industrial scenario, chromium (Cr) as a metal is of great importance but poses a major threat to the ecosystem. In the present study, the effect of different levels of Cr, i.e., 0 (no Cr), 50, and 100 µM in the soil on growth, photosynthetic pigments, gas exchange characteristics, oxidative stress biomarkers, antioxidants machinery (enzymatic and non-enzymatic antioxidants), ions uptake, organic acids exudation, and Cr uptake in different parts of plant were investigated with and without the exogenous application of choline chloride i.e., 0 (no choline chloride), 2–5 mM in Cr-stressed spinach (Spinacia oleracea L.). Our results depicted that Cr addition to the soil significantly (P < 0.05) decreased plant growth and biomass, gas exchange attributes, and minerals uptake by S. oleracea as compared to the plants grown without addition of Cr. However, Cr toxicity boosted the production of reactive oxygen species (ROS) by increasing the contents of malondialdehyde (MDA), which is the indication of oxidative stress in S. oleracea and was also manifested by hydrogen peroxide (H2O2) contents and electrolyte leakage to the membrane-bounded organelles. Although activities of various antioxidative enzymes like superoxidase dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) and non-enzymatic antioxidants like phenolic, flavonoid, and ascorbic acid, anthocyanin contents initially increased up to a Cr level of 50 µM but decreased gradually with the further increased in the Cr level of 100 µM in the medium, compared to those plants which were grown in the control treatment. Results also revealed that the soluble sugar, reducing sugar, and non-reducing sugar were decreased in plants grown under elevating Cr levels but increased the Cr accumulation in the roots and shoots of S. oleracea. Although results also illustrated that the application of choline chloride also decreased Cr toxicity in S. oleracea seedlings by increasing antioxidant capacity and, thus, improved the plant growth and biomass, photosynthetic pigments, gas exchange characteristics, and decrease oxidative stress in the roots and shoots of S. oleracea seedlings, compared to those plants which were not artificially supplied by choline chloride. Research findings, therefore, suggested that the choline chloride application can ameliorate Cr toxicity in S. oleracea seedlings and resulted in improved plant growth and composition under metal stress as depicted by balanced exudation of organic acids.Graphic Abstract

Soil contamination with toxic heavy metals [such as lead (Pb)] is becoming a serious global problem due to the rapid development of the social economy. However, accumulation of Pb in plant parts is very toxic for plant growth and decreases crop yield and productivity. In the present study, we have investigated the different concentrations of Pb in the soil i.e., [0 (no Pb), 50, and 100 mg kg –1 ] to study plant growth and biomass, photosynthetic pigments and gas exchange characteristics, oxidative stress indicators and the response of various antioxidants (enzymatic and non-enzymatic), nutritional status of the plant, organic acid exudation pattern and also Pb accumulation in the roots and shoots of the plants of two varieties of tomato ( Solanum lycopersicum L.) i.e., Roma and Cchuas, grown under different levels of synergic acid [no spray (NS), water spray (WS), 0.3-0.5°μM]. Results from the present study showed that the increasing levels of Pb in the soil decreased non-significantly ( P < 0.05) shoot length, root length, shoot fresh weight, root fresh weight, shoot dry weight, root dry weight, chlorophyll-a, chlorophyll-b, total chlorophyll, carotenoid content, net photosynthesis, stomatal conductance, transpiration rate, soluble sugar, reducing sugar, non-reducing sugar contents, calcium (Ca 2+ ), magnesium (Mg 2+ ), iron (Fe 2+ ), and phosphorus (P) contents in the roots and shoots of the plants. However, Pb toxicity also induced oxidative stress in the roots and shoots of the plants by increasing malondialdehyde (MDA), hydrogen peroxide (H 2 O 2 ), and electrolyte leakage (EL) which also induced increased the compounds of various enzymatic and non-enzymatic antioxidants and also organic acids exudation pattern in the roots such as fumaric acid, acetic acid, citric acid, formic acid, malic acid, oxalic acid contents and increased the concentration of Pb in different parts of the plants. Results also show that the Cchuas showed better growth and development compared to Roma, under the same levels of Pb in the soil. The alleviation of Pb toxicity was induced by the application of synergic acid, and results showed that the application of synergic acid increased plant growth and biomass and also increased the gas exchange characteristics and antioxidant capacity in the roots and shoots of the plants. Research findings, therefore, suggested that synergic acid application can ameliorate Pb toxicity in S. lycopersicum varieties and result in improved plant growth and composition under metal stress as depicted by balanced exudation of organic acids.

The role of morpho-anatomical adaptations of six Kyllinga brevifolia populations in successfully invading hyper-saline environments was investigated. Physiological and anatomical characteristics showed a high degree of plasticity indicating its adaptability potential to a variety of environmental conditions. The population from hyper-saline saltmarsh Sahianwala was exposed to physiological drought for a long time and its survival relied on the prevention of water loss attained by decreased stomatal density and area, lignin deposition in the inner and outer cortical region, especially outside vascular tissue. Larger cells of cortical storage parenchyma aided in water storage and wide metaxylem vessels in better conduction of solutes. Higher accumulation of shoot Ca2+ in this habitat protected neutralized the impact of the enhanced shoot and root Na+ ion uptake. Organic osmoprotectants like total free amino acid, proline, soluble proteins, and sugars accumulated in a higher quantity that contributed towards an osmotic adjustment in Sahianwala population. Population from seasonal inundation (Treemu Headworks) showed larger root aerenchyma to supply sufficient oxygen for respiration, broader xylem vessels for better water and nutrient conduction, and greater density of leaf stomata for better transpiration. Maximum shoot and root length, total leaf area, and water potential were observed in the least saline Chinyot population indicating its best growth potential in a slightly saline aquatic environment. Each population showed specific physiological and anatomical modifications to colonize their respective habitats.

BackgroundThe button mangrove (Conocarpus erectus L.) is regarded as a peripheral species within mangrove communities. This particular species has the ability to thrive in regions that are arid or semiarid, where there is limited availability of nutrients. This study provides evidence of the ecological dominance of Conocarpus erectus across various habitats, highlighting its adaptability and success throughout the country of Pakistan. We collected twelve populations from four distinct ecological regions, including artificial forest plantations, agricultural fields, roadsides, and wastelands, offering a comprehensive assessment of C. erectus adaptability across diverse environmental contexts.ResultsForest plantation populations exhibited impressive shoot growth and moderate root lengths, with plants generally tall and well-weighted. Physiologically, they had moderate chlorophyll content and low carotenoid levels, with a balanced chlorophyll a/b ratio, indicating stable photosynthetic activity. Anatomically, these populations had thicker epidermal and cortical root layers but smaller vascular bundles and phloem regions. Stem and leaf structures were generally moderate in size, with thicker midribs and cortical layers in the leaves. Agricultural field populations showed robust shoot and root systems with balanced fresh and dry biomass. They exhibited high chlorophyll and carotenoid levels, indicating strong photosynthetic capacity. Root and stem anatomy revealed larger root areas, thicker cortex, and wide vascular bundles, reflecting enhanced structural development. Leaves from these populations had moderate midrib and cortical thickness, with larger stomatal areas, promoting efficient gas exchange. Roadside populations displayed deeper roots and reduced biomass production. These populations adapted to environmental stress through leaf expansion, with high leaf numbers and areas. Physiologically, populations had high chlorophyll content, with a high chlorophyll a/b ratio. Root and stem anatomy showed compact structures with smaller vascular bundles, indicating adaptation to harsher conditions. Leaf anatomy was moderate, with smaller vascular bundles and reduced water transport capacity. Wasteland populations exhibited poor growth and high shoot biomass despite small leaves. Physiologically, these populations had the highest total soluble protein and proline contents, reflecting stress adaptation. Anatomically, root and stem structures were variable, with some populations showing reduced cortical cell areas and smaller vascular bundles, indicating limited resource transport. Leaf structures had thicker lamina, thinner epidermal layers, and lower stomatal densities, reflecting adaptation to nutrient-poor soils.ConclusionThis study reveals the adaptability and thriving potential of Conocarpus erectus across varied habitats, providing key insights into its resilience and survival strategies. Understanding these adaptive traits can support habitat restoration, conservation planning, and improve species management in diverse environmental conditions, especially in response to climate change and habitat degradation.

Background Yellow (stripe) rust, caused by Puccinia striiformis f. sp. tritici (Pst), is an economic disease of wheat. Growth-promoting fungi (GPF) such as Trichoderma asperellum and Penicillium simplicissimum have been investigated for their potential to control yellow rust and their involvement in gene expression of four PR proteins for all-stage resistance. Results Wheat plants (cv. Sids-12) treated individually with each of the biocontrol agents, P. simplicissimum and T. asperellum , at 24 and 48 hpi showed a resistance response (infection type = 2) to yellow rust, compared to the non-treated plants, which showed highly susceptible response (infection type = 9). Both biocontrol agents induced resistance against yellow rust on wheat plants, exhibiting a moderate resistance (10 MR) and reduced the colony size of Pst (0.6 mm 2 ). Moreover, P. simplicissimum and T. asperellum increased ( P  ≤ 0.05) the grain yields of wheat plants infected with Pst. Scanning electron microscope (SEM) of yellow rust infected wheat leaves treated with P. simplicissimum and T. asperellum at 24 and 48 hpi showed hyperparasitism on Pst urediniospores and inhibition of the spore germination. Expressions of pathogenesis-related ( PR ) protein genes, PR1, PR2, PR3 and PR4 were higher in wheat plants treated with both biocontrol agents than the non-treated checks. Conclusion P. simplicissimum and T. asperellum exhibited biocontrol potential against yellow rust disease caused by P. striiformis f. sp. tritici (Pst) on wheat plants. It was found that wheat defence mechanism against Pst was activated by a high expression of PR protein genes induced by both biocontrol agents.

While of lesser prevalence than boron (B) deficient soils, B-rich soils are important to study as they can cause B toxicity in the field and subsequently decrease crop yields in different regions of the world. We have conducted the present study to examine the role of the individual or combined application of silicon (Si) and NPK fertilizer in B-stressed spinach plants ( Spinacia oleracea L.). S . oleracea seedlings were subjected to different NPK fertilizers, namely, low NPK (30 kg ha –2 ) and normal NPK (60 kg ha –2 )], which were also supplemented by Si (3 mmol L –1 ), for varying levels of B in the soil i.e., 0, 250, and 500 mg kg –1 . Our results illustrated that the increasing levels of B in the soil caused a substantial decrease in the plant height, number of leaves, number of stems, leaf area, plant fresh weight, plant dry weight, chlorophyll a, chlorophyll b, total chlorophyll, carotenoid content, net photosynthesis, stomatal conductance, transpiration rate, magnesium content in the roots, magnesium contents in the shoots, phosphorus content in the roots, phosphorus content in the leaves in the shoots, iron content in the roots, iron content in the shoots, calcium content in the roots, and calcium content in the shoots. However, B toxicity in the soil increased the concentration of malondialdehyde, hydrogen peroxide, and electrolyte leakage which were also manifested by the increasing activities of enzymatic [superoxidase dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX)], and non-enzymatic antioxidants (phenolic, flavonoid, ascorbic acid, and anthocyanin content). B toxicity in the soil further increased the concentration of organic acids in the roots such as oxalic acid, malic acid, formic acid, citric acid, acetic acid, and fumaric acid. The addition of Si and fertilizer levels in the soil significantly alleviated B toxicity effects on S . oleracea by improving photosynthetic capacity and ultimately plant growth. The increased activity of antioxidant enzymes in Si and NPK-treated plants seems to play a role in capturing stress-induced reactive oxygen species, as was evident from the lower levels of oxidative stress indicators, organic acid exudation, and B concentration in the roots and shoots of Si and NPK-treated plants. Research findings, therefore, suggested that the Si and NPK application can ameliorate B toxicity in S. oleracea seedlings and result in improved plant growth and composition under metal stress as depicted by the balanced exudation of organic acids.

Soil contamination with toxic heavy metals [such as arsenic (As)] is becoming a serious global problem due to rapid development of social economy. Silicon (Si), being an important fertilizer element, has been found effective in enhancing plant tolerance against biotic and abiotic stresses. For this purpose, we have designed the current experiment to explore the contribution of Si in mediating growth and eco-physiology by alleviating As stress in a leafy vegetable spinach ( Spinacia oleracea L.). Fifteen days old seedlings of S. oleracea were subjected to the different concentrations of As, i.e., 0 (no As), 50, and 100 µM in the soil which were also supplied with the different exogenous levels of Si, i.e., 0 (no Si), 1.5, and 3 mM. Results from the present study revealed that the As toxicity induced a substantial decreased in shoot length, root length, number of leaves, leaf area, shoot fresh weight, root fresh weight, shoot dry weight, root dry weight, chlorophyll-a, chlorophyll-b, total chlorophyll, carotenoid content, net photosynthesis, stomatal conductance, transpiration rate, soluble sugar, reducing sugar, non-reducing sugar contents, calcium (Ca 2+ ), magnesium (Mg 2+ ), iron (Fe 2+ ), and phosphorus (P) contents in the roots and shoots of the plants. In contrast, increasing levels of As in the soil significantly ( P  < 0.05) increased As concentration in the roots and shoots of the plants, phenolic content, malondialdehyde (MDA), hydrogen peroxide (H 2 O 2 ), electrolyte leakage (EL), fumaric acid, acetic acid, citric acid, formic acid, malic acid, oxalic acid contents in the roots of the plants. Although, the activities of enzymatic antioxidants such as superoxidase dismutase, peroxidase, catalase, ascorbate peroxidase in the roots and shoots of the plants and non-enzymatic such as phenolic, flavonoid, ascorbic acid, and anthocyanin contents were initially increased with the exposure of 50 µM As, but decreased by the increasing the As concentration 100 µM in the soil. Addition of Si into the soil significantly alleviated As toxicity effects on S . oleracea by improving photosynthetic capacity and ultimately plant growth. Increased activities of antioxidant enzymes in Si-treated plants seem to play a role in capturing stress-induced reactive oxygen species as was evident from lower level of MDA, H 2 O 2 , MDA, and EL in Si-treated plants. Research findings, therefore, suggested that Si application can ameliorate As toxicity in S . oleracea seedlings and resulted in improved plant growth and composition under metal stress as depicted by balanced exudation of organic acids.

For the current study, Bougainvillea flowers as environment friendly sustainable source of plant-based natural dye have been selected as an alternative to toxic synthetic dyes for dyeing of cotton and silk. Natural colorant from Bougainvillea flowers ( Bougainvillea glabra ) was extracted using aqueous and acidic extraction media. Maximum colorant was extracted in aqueous medium, and further it was used for cotton and silk dyeing. The optimum values of the dyeing parameters including dyeing time, dye to liquor ratio and salt level as exhausting agent were found to be 30 min, 35-mL liquor ratio and 3.0 g for cotton and for silk 45 min dyeing time, 45-mL liquor ratio and 3.0 g exhausting agent in aqueous dye extract. Bio mordanting has been applied to attain a variety of color shades. The utilization of 3% of henna, 4% of turmeric for silk pre-mordanting and for post-mordanting turmeric at 3% and henna at 4% for silk gave a darker shade. For cotton bio mordanting, 2% turmeric rhizome powder, 3% henna leaves powder extract as pre-mordant and 2% turmeric, 3% henna as post-mordant has developed a variety of shade. Overall, it has been found that natural colorant from Bougainvillea flowers is the new dye source for bio-coloration of natural fabrics, and addition of bio mordants has made the process more calming and eco-friendly. Graphical abstract