Sumera Iqbal

Among the various stresses affecting crop productivity, drought is a major challenge, particularly for leguminous crops like peas. The present study investigated the potential of chitosan-zinc oxide nanoparticles (CHT-ZnO NPs) to enhance drought tolerance in Pisum sativum L. through foliar...

Fungal pathogens pose a serious threat to wheat productivity by impairing plant water relations, membrane integrity, and metabolic functions. Recent advances in nanotechnology have highlighted the potential of nanoparticles as priming agents to enhance plant tolerance against biotic stresses. Therefore, this study evaluated the efficacy of silver nanoparticles (AgNPs) and silica nanoparticles (SiNPs) in modulating physiological and biochemical responses of wheat under fungal stress. Fungal infection significantly reduced relative water content (RWC), membrane stability index (MSI), protein content, osmotic potential, and photosynthetic pigments, while increasing soluble sugars, proline accumulation, and antioxidant enzyme activities. However, nanoparticle priming markedly alleviated these adverse effects in a concentration-dependent manner. AgNPs at 50-75 mg L⁻¹ and SiNPs at 50-100 mg L⁻¹ significantly improved RWC and MSI under stress. Protein content was maximized at 75 mg L⁻¹ AgNPs and 100 mg L⁻¹ SiNPs. Both nanoparticles further enhanced soluble sugar accumulation and reduced osmotic potential, indicating improved osmotic adjustment. Chlorophyll and carotenoid contents were notably enhanced, particularly with 75 mg L⁻¹ AgNPs and 100 mg L⁻¹ SiNPs. Although proline levels increased under stress, nanoparticle treatments generally reduced its accumulation compared to untreated stressed plants. Furthermore, higher concentrations of both nanoparticles significantly stimulated antioxidant enzyme activities (SOD, POD, and CAT), strengthening the plant defense system. In conclusion, AgNPs and SiNPs alleviate fungal stress in wheat by enhancing physiological stability and biochemical defenses, with 75 mg L⁻¹ AgNPs and 100 mg L⁻¹ SiNPs identified as optimal concentrations for improving stress tolerance and supporting sustainable crop protection.

Sclerotium rolfsii is a necrotrophic fungus responsible for the development of Southern Blight disease in a variety of host plants such as tomato, sugar beet, legumes, crucifers, and cucurbits. The present research was conducted to determine the in vitro antifungal activity of Linum usitatissimum extracts against the pathogenic fungus Sclerotium rolfsii strain FCBP-PTF-771. To attain this goal, an in vitro antifungal bioassay was performed using a methanolic extract (MeOH) of L. usitatissimum against S. rolfsii. Concentrations of 1.5% and 1.75% exhibited the highest antifungal activity, inhibiting growth up to 80% and 75%, respectively. Bioassay guided-frac­tionation of the MeOH extract was performed using solvents including n-hexane, chloroform, ethyl acetate, and n-butanol, followed by in vitro analysis of the resulting fractions to confirm the antifungal activity of the most potent fraction. The n-butanol fraction was found to be highly effective at concentrations of 0.4% and 0.6% c and inhibited the growth of the test fungus by approximately 70% and 72%, respectively. Subsequently, the n-butanol fraction was subjected to gas chromatography-mass spectrometry (GC-MS), with a total of thirty-seven compounds identified among which benzenedicarboxylic acid was present in the maximum amount. These findings suggest that extracts of L. usitatissimum can be employed as a potent antifungal source against S. rolfsii due to the presence of a vast array of phytochemicals. In addition, the bioactive compounds identified in the n-butanol fraction of this plant contribute to its fungicidal potency.

Drought stress poses a significant threat to rice productivity, particularly when rice is cultivated through the direct seeded system (DSR). This paper aimed to isolate and characterize drought-tolerant plant growth-promoting rhizobacteria (PGPR) from rice rhizospheric soils in arid and semi-arid areas of Pakistan and assess their efficacy in improving rice growth under drought conditions. Six isolates exhibited PGPR traits such as phosphate solubilization, indole 3-acetic acid production, ACC deaminase activity, siderophore production, and osmolyte accumulation. Pot experiments under drought stress (60% field capacity) demonstrated that inoculation with PGPR enhanced the germination rate, chlorophyll level, water status, membrane stability, and biochemical parameters in rice exceptionally. Among these, isolate NRC13, identified as Bacillus velezensis, showed the greatest efficacy in enhancing physiological, biochemical, and yield characteristics, including grain yield and 1000-grain weight under drought stress. This study provides the first evidence of Bacillus velezensis NRC13’s application in direct-seeded rice under drought conditions in Pakistan, demonstrating the potential of this novel bio-inoculant to increase rice productivity and resilience in water-deficient settings.

Oxidative stress mediated by reactive oxygen species (ROS) is a common denominator in arsenic toxicity. Arsenic stress in soil affects the water absorption, decrease stomatal conductance, reduction in osmotic, and leaf water potential, which restrict water uptake and osmotic stress in plants. Arsenic-induced osmotic stress triggers the overproduction of ROS, which causes a number of germination, physiological, biochemical, and antioxidant alterations. Antioxidants with potential to reduce ROS levels ameliorate the arsenic-induced lesions. Plant growth promoting rhizobacteria (PGPR) increase the total soluble sugars and proline, which scavenging OH radicals thereby prevent the oxidative damages cause by ROS. The main objective of this study was to evaluate the potential role of Arsenic resistant PGPR in growth of maize by mitigating arsenic stress. Arsenic tolerant PGPR strain MD3 (Pseudochrobactrum asaccharolyticum) was used to dismiss the ‘As’ induced oxidative stress in maize grown at concentrations of 50 and 100 mg/kg. Previously isolated arsenic tolerant bacterial strain MD3 “Pseudochrobactrum asaccharolyticum was used for this experiment. Further, growth promoting potential of MD3 was done by germination and physio-biochemical analysis of maize seeds. Experimental units were arranged in Completely Randomized Design (CRD). A total of 6 sets of treatments viz., control, arsenic treated (50 & 100 mg/kg), bacterial inoculated (MD3), and arsenic stress plus bacterial inoculated with three replicates were used for Petri plates and pot experiments. After treating with this MD3 strain, seeds of corn were grown in pots filled with or without 50 mg/kg and 100 mg/kg sodium arsenate. The plants under arsenic stress (100 mg/kg) decreased the osmotic potential (0.8 MPa) as compared to control indicated the osmotic stress, which caused the reduction in growth, physiological parameters, proline accumulation, alteration in antioxidant enzymes (Superoxide dismutase-SOD, catalase-CAT, peroxidase-POD), increased MDA content, and H2O2 in maize plants. As-tolerant Pseudochrobactrum asaccharolyticum improved the plant growth by reducing the oxidation stress and antioxidant enzymes by proline accumulation. PCA analysis revealed that all six treatments scattered differently across the PC1 and PC2, having 85.51% and 9.72% data variance, respectively. This indicating the efficiency of As-tolerant strains. The heatmap supported the As-tolerant strains were positively correlated with growth parameters and physiological activities of the maize plants. This study concluded that Pseudochrobactrum asaccharolyticum reduced the ‘As’ toxicity in maize plant through the augmentation of the antioxidant defense system. Thus, MD3 (Pseudochrobactrum asaccharolyticum) strain can be considered as bio-fertilizer.

Contamination of the environment due to speedup of anthropogenic activities has become a serious threat to modern humanity. Among the contaminants, the new emerging concern is the heavy metal (HM) contamination in the environment. Because the persistence and harmfulness of heavy metals affect the ecosystem and the health of plants, animals, and humans, they are the most toxic substances in the environment. Among them, Arsenic (As) emerged as major environmental constraint leading to enormous negative effects on the plant, animal, and human health. Even in minute quantity, As is known to cause various critical diseases in humans and toxicity in plants. Research was performed to observe the capability of plant growth–promoting strains of bacteria in enhancing Zea mays (L.) growth in arsenic polluted soil. Total 30 bacterial strains were isolated from the polluted soils, screened for plant growth promotion potential and arsenic tolerance. Eighteen isolates showed resistance to different levels of sodium arsenate (ranging from 0 to 50 mM) in agar plate using LB media. Of 18 isolates, 83.3% produced IAA, methyl red, and hydrogen cyanide; 55.5% exhibited catalase activity; 61.1% showed siderophore production; 88.8% showed phosphate solubilization; and 44.4% showed oxidase, Voges proskauer activity, and KOH solubility. The most efficient isolates SR3, SD5, and MD3 with significant arsenic tolerance and plant growth–promoting (PGP) activity were examined via sequencing of amplified 16S rRNA gene. Isolates of bacteria, i.e., SR3, SD5, and MD3, showing multiple PGP-traits were identified as Bacillus pumilus (NCBI accession number: OR459628), Paenibacillus faecalis (NCBI accession number: OR461560), and Pseudochrobactrum asaccharolyticum (NCBI accession number: OR458922), respectively. Maize seeds treated with these PGPR strains were grown in pots contaminated with 50 ppm and 100 ppm sodium arsenate. Compared to untreated arsenic stressed plants, bacterial inoculation P. asaccharolyticum (MD3) resulted 20.54%, 18.55%, 33.45%, 45.08%, and 48.55% improvement of photosynthetic pigments (carotenoid content, chlorophyll content, stomatal conductance (gs), substomatal CO₂, and photosynthetic rate), respectively. Principal component analysis explained that first two components were more than 96% of the variability for each tested parameter. The results indicate that in comparison to other isolates, P. asaccharolyticum isolate can be used as efficient agent for improving maize growth under arsenic polluted soil. Graphical Abstract

Aims: Salinity adversely affects okra [Abelmoschus esculentus (L.) Moench] plants by inducing osmotic and oxidative stresses. This study was designed to enhance salinity-induced osmotic and oxidative stress tolerance in okra plants by applying organic amendments. Methods: The effects of different organic amendments (municipal solid waste compost, farmyard manure (FYM) and press mud) on osmotic potential, water use efficiency, activities of antioxidant enzymes, total soluble sugar, total soluble proline, total soluble protein and malondialdehyde (MDA) contents of okra plants grown under saline conditions (50 mM sodium chloride) were evaluated in a pot experiment. The organic amendments were applied each at the rate of 5% and 10% per pot or in various combinations (compost + FYM, FYM + press mud and compost + press mud each at the rate of 2.5% and 5% per pot). Results: As compared to control, high total soluble sugar (60.41), total soluble proline (33.88%) and MDA (51%) contents and increased activities of antioxidant enzymes [superoxide dismutase (83.54%), catalase (78.61%), peroxidase (53.57%] in salinity-stressed okra plants, were indicative of oxidative stress. Salinity significantly reduced the osmotic potential (41.78%) and water use efficiency (4.75%) of okra plants compared to control. Under saline conditions, 5% (farmyard manure + press mud) was the most effective treatment, which significantly improved osmotic potential (27.05%), total soluble sugar (4.20%), total soluble protein (73.62%) and total soluble proline (23.20%) contents and superoxide dismutase activity (32.41%), compared to saline soil. Application of 2.5% (FYM + press mud), 5% press mud, and 10% compost significantly reduced MDA content (27%) and improved activities of catalase (38.64%) and peroxidase (48.29%), respectively, compared to saline soil, thus facilitated to alleviate oxidative stress in okra plants. Conclusions: Using organic amendments (municipal solid waste compost, farmyard manure and press mud) was a cost-effective approach to improve salinity-induced osmotic and oxidative stress tolerance in okra plants.

Contamination of the environment due to speedup of anthropogenic activities become a serious threat to modern humanity. Among the contaminant the new emerging concern is the heavy metals (HMs) contamination in the environment. Because the persistence and harmfulness of heavy metals affect the ecosystem and the health of plants, animals and humans, they are the most toxic substances in the environment. Among them, Arsenic (As) emerged as major environmental constraint leading to enormous negative effects on the plant, animal and human health. Even in minute quantity, As is known to cause various critical diseases in humans and toxicity in plants. Research was performed to observe the capability of plant growth promoting strains of bacteria in enhancingZea mays(L.) growth in arsenic polluted soil. Total 30 bacterial strains were isolated from the polluted soils, screened for plant growth promotion potential and arsenic tolerance. Eighteen isolates showed resistance to different levels of sodium arsenate (ranging from 0 to 50 mM) in agar plate using LB media. Of 18 isolates, 83.3% produced IAA, methyl red and hydrogen cyanide, 55.5% exhibited catalase activity, 61.1% showed siderophore production, 88.8% showed phosphate solubilization and 44.4% showed oxidase, Voges proskauer activity and KOH solubility. The most efficient isolates SR3, SD5 and MD3 with significant arsenic tolerance and plant growth promoting (PGP) activity were examined via sequencing of amplified 16S rRNA gene. Isolates of bacteria i.e., SR3, SD5 and MD3 showing multiple PGP-traits were identified asBacillus pumilus(NCBI accession number: OR459628),Paenibacillus faecalis(NCBI accession number: OR461560) andPseudochrobactrum asaccharolyticum(NCBI accession number: OR458922), respectively. Maize seeds treated with these PGPR strains were grown in pots contaminated with 50 ppm and 100 ppm sodium arsenate. Compared to untreated arsenic stressed plants, bacterial inoculationPseudochrobactrum asaccharolyticum(MD3) resulted 20.54%, 18.55%, 33.45%, 45.08% and 48.55% improvement of photosynthetic pigments (carotenoid content, chlorophyll content, stomatal conductance (gs), substomatal CO₂and photosynthetic rate respectively. Principal component analysis explained that first two components were more than 96% of the variability for each tested parameter. The results indicate that in comparison to other isolates,Pseudochrobactrum asaccharolyticumisolate can be used as efficient agent for improving maize growth under arsenic polluted soil.

Background: Parthenium hysterophorus L. is one of the top ten worst weeds globally and is recorded in the global database of invasive species. Objective: The current study was aimed to evaluate the herbicidal potential of Alternaria brassicicola (Schwein.) Wiltshire and Alternaria gaisen Nagano. culture filtrates against a problematic weed P. hysterophorus. Methods: A. brassicicola and A. gaisen culture filtrates were tested in vitro against the test weed. A. gaisen culture filtrates were found most effective against the test weed, [...] Background: Parthenium hysterophorus L. is one of the top ten worst weeds globally and is recorded in the global database of invasive species. Objective: The current study was aimed to evaluate the herbicidal potential of Alternaria brassicicola (Schwein.) Wiltshire and Alternaria gaisen Nagano. culture filtrates against a problematic weed P. hysterophorus. Methods: A. brassicicola and A. gaisen culture filtrates were tested in vitro against the test weed. A. gaisen culture filtrates were found most effective against the test weed,