Reduced Plant Growth Research Articles

IMPACT OF DIFFERENT ORGANIC AND INORGANIC AMENDMENTS ON GROWTH AND YIELD OF MUNG BEAN IRRIGATED WITH TEXTILE EFFLUENTS

Water is an important substance for all life on earth, and it is essential for human beings, financial improvement, and the existence of ecological units. The quality and quantity of the water supply is very important, especially during irrigation. Due to the extensive measurement of water and colour associated with the manufacturing process, textile printing, and dyeing production lines around the world pose a major environmental risk. Textile wastewater contains a lot of pollutants including pH, temperature, shade, COD, BOD, TSS, TDS, EC, and heavy metals. This textile runoff continues to irrigate agricultural land, causing contamination of soils and plant systems with heavy metals. Therefore, adding organic and inorganic modifiers to soil is an effective technique for fixing heavy metals. Irrigate pots with textile wastewater of selected concentrations (10%, 25%, 50%, and 100%) collected in specific industrial sectors. The parameters of vegetative growth are reduced by increasing the concentration of textile effluent. Note the substantial reduction in the growth of plants applying wastewater at 100% concentration. In the case of T5, a significant increase in growth parameters was observed, where only tap water was used to pressurize the sludge, while dilute wastewater also enhanced growth at concentrations of 10% and 25%. For the chlorophyll content of mung bean plants, when the wastewater concentration is 100%, the recorded decrease is greater, followed by 10% and 25% respectively. The presence of heavy metals in wastewater reduces plant growth. In the experiment, all four treatments contained organic amendments (pressed sludge, poultry manure, biogas slurry, and farmyard manure). The other four treatment methods are pressure treatment of textile wastewater and the amount of organic modifier is 2%. By adding a correcting agent, the utilization rate of Cr is reduced, as the correcting agent will increase the pH of the soil, thus reducing the solubility of the metal. In addition, Cr can form insoluble complexes with organic materials, thus reducing its solubility.

The Molecular Mechanism of Cold-Stress Tolerance: Cold Responsive Genes and Their Mechanisms in Rice (Oryza sativa L.).

Rice (Oryza sativa L.) production is highly susceptible to temperature fluctuations, which can significantly reduce plant growth and development at different developmental stages, resulting in a dramatic loss of grain yield. Over the past century, substantial efforts have been undertaken to investigate the physiological, biochemical, and molecular mechanisms of cold stress tolerance in rice. This review aims to provide a comprehensive overview of the recent developments and trends in this field. We summarized the previous advancements and methodologies used for identifying cold-responsive genes and the molecular mechanisms of cold tolerance in rice. Integration of new technologies has significantly improved studies in this era, facilitating the identification of essential genes, QTLs, and molecular modules in rice. These findings have accelerated the molecular breeding of cold-resistant rice varieties. In addition, functional genomics, including the investigation of natural variations in alleles and artificially developed mutants, is emerging as an exciting new approach to investigating cold tolerance. Looking ahead, it is imperative for scientists to evaluate the collective impacts of these novel genes to develop rice cultivars resilient to global climate change.

EuMYB308 regulates lignin accumulation by targeting EuLAC17 in Eucalyptus urophylla

It is known that laccase genes are involved in lignin synthesis. Eucalyptus is an important timber species; functional studies of specific laccase members and their upstream regulatory factors in Eucalyptus are incomplete, and the mechanism of lignin content variation in polyploid plants remains unclear. Therefore, in this study, we investigated the function of EuLAC17 by overexpressing it in tobaccos and the result showed the lignin content in transgenic tobacco increased significantly. Further, yeast one hybrid sequencing was used to identify a series of potential regulatory factors of EuLAC17, among which EuMYB308 showed the most significant correlation with EuLAC17. Yeast one hybrid, dual-luciferase reporter gene assay and electrophoretic mobility shift assay jointly verified that EuMYB308 could directly target the EuLAC17 promoter and repress its expression. In addition, overexpression of EuMYB308 resulted in significant reductions in plant growth, xylem cell lumen area, cell wall thickness and lignin content. Transcriptome sequencing showed that lignin biosynthesis genes including laccase genes were significantly differential expression in transgenic plants compared with wild-type plants. In triploid Eucalyptus urophylla, the expression of EuMYB308 was significantly upregulated, which may enhance the inhibition of EuLAC17 and thus reduce its expression level in triploid, which is one possible reason for the reduced lignin content in triploid E. urophylla. This study provides important insights into transcriptional regulation of lignin biosynthesis in Eucalyptus, and also contributes to revealing the genetic mechanism of lignin content variation in polyploid plants, which are of great significance for promoting the improvement of wood quality in forest trees and polyploid breeding.

Physiological and molecular analysis of pitaya (Hylocereus polyrhizus) reveal up-regulation of secondary metabolites, nitric oxide, antioxidant defense system, and expression of responsive genes under low-temperature stress by the pre-treatment of hydrogen peroxide

Low-temperature events are one of the leading environmental cues that considerably reduce plant growth and shift species biodiversity. Hydrogen peroxide (H2O2) is a signaling molecule that has a distinguished role during unfavorable conditions and shows outstanding perspectives in low-temperature stress. Herein, we elucidated the protective role and regulatory mechanism of H2O2 in alleviating the deleterious effects of low-temperature stress in pitaya plants. Micropropagated pitaya plants were cultured in Murashige and Skoog media supplemented with different levels of H2O2 (0, 5, 10, and 20 mM) and then exposed to low-temperature stress (5 °C for 24 h). H2O2 at 10 mM, improved low-temperature stress tolerance by relieving oxidative injuries and ameliorating growth parameters in terms of fresh weight (66.7%), plant length (16.7%), and pigments content viz., chlorophyll a (157.4%), chlorophyll b (209.1%), and carotenoids (225.9%). H2O2 counteracted the low-temperature stress by increasing amino acids (224.7%), soluble proteins (190.5%), and sugars (126.6%). Simultaneously, secondary metabolites like ascorbic acid (ASA), anthocyanins, phenolics, flavonoids, total antioxidant (TOA), and proline were also up-regulated by H2O2 (104.9%, 128.8%, 166.3%, 141.4%, and 436.4%, respectively). These results corresponded to the stimulative role triggered by H2O2 in boosting the activities of catalase (22.4%), ascorbate peroxidase (20.7%), superoxide dismutase (88.4%), polyphenol oxidase (60.7%), soluble peroxidase (23.8%), and phenylalanine ammonia-lyase (57.1%) as well as the expression level of HpCAT, HpAPX, HpSOD, HpPPO, and HpPAL genes, which may help to moderate low-temperature stress. In conclusion, our findings stipulate new insights into the mechanisms by which H2O2 regulates low-temperature stress tolerance in pitaya plants.

Mitigating the effects of PVC microplastics and mercury stress on rye (Secale cereale L.) plants using zinc oxide−nanoparticles

AbstractIn present years, the use of zinc oxide nanoparticles (ZnO‐NPs) has received great attention due to increase in the nutrient accumulation by plants for improving the capability of agronomic Zn biofortification. Although, the emergence of polyvinyl chloride (PVC) microplastics (MPs) as pollutants in agricultural soils is increasingly alarming, presenting significant toxic threats to soil ecosystems. The present work studied the impact of different levels of PVC‐MPs, namely 0 (no PVC‐MPs), 2, and 4 mg L−1, along with mercury (Hg) levels of 0 (no Hg), 10, and 25 mg kg−1 in the soil, while concurrently applying with ZnO‐NPs at 0 (no ZnO‐NPs), 50, and 100 μg mL−1 to rye (Secale cereale L.) plants. This study aimed to examine plant growth and biomass, photosynthetic pigments and gas exchange characteristics, oxidative stress indicators, and the response of various antioxidants (enzymatic and non‐enzymatic) and their specific gene expression, proline metabolism, the ascorbic acid–dehydroascorbic acid (AsA–GSH) cycle, and cellular fractionation in the plants. The research outcomes indicated that elevated levels of PVC‐MPs and Hg stress in the soil notably reduced plant growth and biomass, photosynthetic pigments, and gas exchange attributes. However, PVC‐MPs and Hg stress also induced oxidative stress in the roots and shoots of the plants by increasing malondialdehyde (MDA), hydrogen peroxide (H2O2), and electrolyte leakage (EL) which also induced increased compounds of various enzymatic and non‐enzymatic antioxidants, and also the gene expression and sugar content. Furthermore, a significant increase in proline metabolism, the AsA–GSH cycle, and the pigmentation of cellular components was observed. Although, the application of ZnO‐NPs showed a significant increase in plant growth and biomass, gas exchange characteristics, enzymatic and non‐enzymatic compounds, and their gene expression and also decreased oxidative stress. In addition, the application of ZnO‐NPs enhanced cellular fractionation and decreased the proline metabolism and AsA–GSH cycle in S. cereale plants. These results open new insights for sustainable agriculture practices and hold immense promise in addressing the pressing challenges of heavy metal contamination in agricultural soils.

Silicon mitigates salinity effects on sorghum-sudangrass (Sorghum bicolor × Sorghum sudanense) by enhancing growth and photosynthetic efficiency.

The aim of this study was to investigate whether silicon (Si) supply was able to alleviate the harmful effects caused by salinity stress on sorghum-sudangrass (Sorghum bicolor ×Sorghum sudanense ), a species of grass raised for forage and grain. Plants were grown in the presence or absence of 150mM NaCl, supplemented or not with Si (0.5mM Si). Biomass production, water and mineral status, photosynthetic pigment contents, and gas exchange parameters were investigated. Special focus was accorded to evaluating the PSI and PSII. Salinity stress significantly reduced plant growth and tissue hydration, and led to a significant decrease in all other studied parameters. Si supply enhanced whole plant biomass production by 50%, improved water status, decreased Na+ and Cl- accumulation, and even restored chlorophyll a , chlorophyll b , and carotenoid contents. Interestingly, both photosystem activities (PSI and PSII) were enhanced with Si addition. However, a more pronounced enhancement was noted in PSI compared with PSII, with a greater oxidation state upon Si supply. Our findings confirm that Si mitigated the adverse effects of salinity on sorghum-sudangrass throughout adverse approaches. Application of Si in sorghum appears to be an efficient key solution for managing salt-damaging effects on plants.

Insights into Key Biometric, Physiological and Biochemical Markers of Magnesium (Mg) Deficiency Stress in the Halophyte Cakile maritima

Magnesium is a key element for plant growth and development. Plant responses to Mg deficiency were well investigated, especially in glycophytes. Such responses include a reduction in plant growth and biomass allocation between shoots and roots, photosynthates partitioning from source to sink organs, the accumulation of carbohydrates, and an induction of several Mg transporters. Some physiological and biochemical parameters are good markers of Mg deficiency stress even though they are not well investigated. In the present study, the halophyte Cakile maritima was subjected to Mg shortage, and several Mg stress indices were analyzed. Our data showed that Mg starvation affected shoot and plant length, leaf number, and plant organ growth. A significant decrease in chlorophyll synthesis and photosynthetic activity was also recorded. Mg deficiency triggered oxidative damage as electrolyte leakage and lipid peroxidation were increased by Mg deficiency while the membrane stability index decreased. For a deeper understanding of the effect of Mg starvation on C. maritima, several tolerance stress indices were evaluated, demonstrating a negative impact of Mg stress on almost all those parameters. This study provided important insights on several markers of Mg deficiency stress, which were informative by themselves as unique and early signals of Mg deficiency stress in this halophyte.

Timely symbiosis: circadian control of legume-rhizobia symbiosis.

Legumes house nitrogen-fixing endosymbiotic rhizobia in specialised polyploid cells within root nodules. This results in a mutualistic relationship whereby the plant host receives fixed nitrogen from the bacteria in exchange for dicarboxylic acids. This plant-microbe interaction requires the regulation of multiple metabolic and physiological processes in both the host and symbiont in order to achieve highly efficient symbiosis. Recent studies have showed that the success of symbiosis is influenced by the circadian clock of the plant host. Medicago and soybean plants with altered clock mechanisms showed compromised nodulation and reduced plant growth. Furthermore, transcriptomic analyses revealed that multiple genes with key roles in recruitment of rhizobia to plant roots, infection and nodule development were under circadian control, suggesting that appropriate timing of expression of these genes may be important for nodulation. There is also evidence for rhythmic gene expression of key nitrogen fixation genes in the rhizobium symbiont, and temporal coordination between nitrogen fixation in the bacterial symbiont and nitrogen assimilation in the plant host may be important for successful symbiosis. Understanding of how circadian regulation impacts on nodule establishment and function will identify key plant-rhizobial connections and regulators that could be targeted to increase the efficiency of this relationship.

Phytoremediation of Arsenic (As) in rice plants, mediated by Bacillus subtilis strain IU31 through antioxidant responses and phytohormones synthesis

Bacteria-assisted phytoremediation uses bacteria to promote plant health and improve its ability to remediate toxic heavy metals like Arsenic (As). Here, we isolated rhizobacteria and identified them as Bacillus subtilis strain IU31 using 16S rDNA sequencing. IU31 showed phosphate solubilization potential on Pikovskaya agar medium and produced siderophores, which were detected on Chromium Azurol-S (CAS) agar medium. Indole-3-acetic acid (IAA) and gibberellins (GAs), namely GA1, GA3, GA4, GA7, GA9, GA12, GA15, and GA24, were quantified by GC/MS-SIM analysis. The expression levels of genes involved in GA and IAA biosynthesis, such as cyp112, cyp114, trpA, and trpB, were assessed using semi-quantitative RT-PCR. Plant bioassays showed that As at a 15 mg/kg concentration reduced plant growth, chlorophyll content, and biomass. However, IU31 inoculation significantly improved plant growth dynamics, enhancing As accumulation by up to 50% compared with uninoculated plants. IU31 inoculation induced the bioconcentration factor (BCF) and bioaccumulation factor (BAF) of As in plants compared to uninoculated plants, but the translocation factor (TF) of As was unaffected by IU31 inoculation. IU31 inoculation effectively restored glutathione-S-transferase (GST) and catalase (CAT) enzyme activities, as well as glutathione (GSH) and hydrogen peroxide concentrations to nearly normal levels, which were significantly elevated in plants exposed to As stress. These results show that IU31 improves plant health and growth by producing IAA and GAs, which might contribute to the uptake and detoxification of As.

A combined landfarming-phytoremediation method to enhance remediation of mixed persistent contaminants.

Contamination of soil and water with petroleum hydrocarbons and metals can pose a significant threat to the environment and human health. This study aimed to investigate the establishment and growth of tall fescue and agropyron in two petroleum-contaminated soils (soil S1 and soil S2) with previous landfarming treatments, and to assess the phytoremediation potential for heavy metal removal from these polluted soils. The results showed that the presence of petroleum hydrocarbons significantly (P < 0.05) reduced plant growth, but plant development was facilitated in soils with prior landfarming treatments. Urease activity in the rhizosphere of agropyron for soil S1 was about 47% higher than the unplanted control soil. The rhizosphere of agropyron and tall fescue eliminated more than 40% and 20% of total hydrocarbon amounts in soil S1, respectively, compared to the unplanted soil. Moreover, the plants grown in the landfarming treatment exhibited higher concentrations of metals (Fe, Zn, Mn, Cu, and Ni) than the control. Based on the findings, the combination of landfarming and phytoremediation techniques can provide an optimal solution for removing mixed pollutants, including petroleum hydrocarbons and metals, from the environment.

PGPB Consortium Formulation to Increase Fermentable Sugar in Agave tequilana Weber var. Blue: A Study in the Field.

Agave tequilana Weber var. Blue is used as the primary raw material in tequila production due to its fructans (inulin) content. This study evaluates the formulation of a plant-growth-promoting bacteria (PGPB) consortium (Pseudomonas sp. and Shimwellia sp.) to increase sugars in A. tequilana under field conditions. A total of three doses were tested: low (5 L ha-1), medium (10 L ha-1), and high (15 L ha-1), with a cellular density of 1 × 108 CFU mL-1 and one control treatment (without application). Total reducing sugars (TRS), inulin, sucrose, glucose, fructose, and plant growth were measured in agave plants aged 4-5 years at 0 (T0), 3 (T3), 6 (T6), and 12 (T12) months. Yield was recorded at T12. The TRS increased by 3%, and inulin by 5.3% in the high-dose treatment compared to the control at T12. Additionally, a low content of sucrose, glucose, and fructose (approximately 1%) was detected. At T12, the weight of agave heads increased by 31.2% in the medium dose and 22.3% in the high dose compared to the control. The high dose provided a higher inulin content. The A. tequilana plants were five years old and exhibited growth comparable to the standards for 6-7-year-old plants. This study demonstrates a sustainable strategy for tequila production, optimizing the use of natural resources and enhancing industry performance through increased sugar content and yield.

Effect of High Salt Stress on Germination and Growth of Some Varieties of Common Beet

Information is provided on soil salinization as the most common abiotic stress that reduces the productivity and quality of agricultural plants. Salt stress is associated with lipid peroxidation in cell membranes, DNA damage, protein denaturation, carbohydrate oxidation, pigment breakdown and disruption of enzymatic activity, as well as metabolic adaptations, including primarily the accumulation of osmolytes. The growth of higher plants in saline soil depends on the salt tolerance of the plant species. Reduced plant growth due to salinity includes a reduction in plant leaf area. A pot experiment plant materials was carried out based on investigate the effect of salt stress on growth and state stomatal of three sugar beet (Beta vulgaris) cultivars, Cooper, Tarifa and Taltos which import from Denmark. Plants were harvested after 30, 45 and 60 days of salt treatment and were separated into leaf lamina, petioles, stem, and roots.

Co-hydrothermal carbonization of municipal sludge and agricultural waste to reduce plant growth inhibition by aqueous phase products: Molecular level analysis of organic matter

The organic matter molecular mechanism by which combined hydrothermal carbonization (co-HTC) of municipal sludge (MS) and agricultural wastes (rice husk, spent mushroom substrate, and wheat straw) reduces the inhibitory effects of aqueous phase (AP) products on pak choi (Brassica campestris L.) growth compared to HTC of MS alone is not clear. Fourier-transform ion cyclotron resonance mass spectrometry was used to characterize the differences in organic matter at the molecular level between AP from MS HTC alone (AP-MS) and AP from co-HTC of MS and agricultural waste (co-Aps). The results showed that N-bearing molecules of AP-MS and co-Aps account for 70.6 % and 54.2 %–64.1 % of all molecules, respectively. Lignins were present in the highest proportion (56.3 %–78.5 %) in all APs, followed by proteins and lipids. The dry weight of co-APs hydroponically grown pak choi was 31.6 %–47.6 % higher than that of the AP-MS. Molecules that were poorly saturated and with low aromaticity were preferentially consumed during hydroponic treatment. Molecules present before and after hydroponics were defined as resistant molecules; molecules present before hydroponics but absent after hydroponics were defined as removed molecules; and molecules absent before hydroponics but present after hydroponics were defined as produced molecules. Large lignin molecules were broken down into more unsaturated molecules, but lignins were the most commonly resistant, removed, and produced molecules. Correlation analysis revealed that N- or S-bearing molecules were phytotoxic in the AP. Tannins positively influenced the growth of pak choi. These results provide new insights into potential implementation strategies for liquid fertilizers produced from AP arising from HTC of MS and agricultural wastes.

Fertiliser supplementation with a PGR complex of chlormequat chloride (CCC) and paclobutrazol (PBZ) alters Cannabis sativa growth

ABSTRACT Cannabis (Cannabis sativa) is a high-value crop, wherein growth within controlled environments is common for the purposes of maximising yield, quality, and uniformity, however, uncontrolled-growth in proximity to artificial lighting can compromise yields. Within the floricultural industry it is common practice to apply plant growth regulators (PGRs) to retard plant growth and maximise yield and quality, with two well-established PGRs being chlormequat chloride (CCC) and paclobutrazol (PBZ). Accordingly, the aim of this study was to investigate the potential of a PGR complex of CCC and PBZ for novel application to cannabis to control plant height. Treatment of cannabis with the PGR complex within an indoor hydroponic growth system resulted in a 91.1% reduction in post-treatment plant growth (p < 0.001) leading to plants with end-point height and internodal spacing (INS) 0.568-fold (p < 0.001) and 0.469-fold (p < 0.001) shorter than control plants, respectively. These results demonstrate the capacity of CCC and PBZ to beneficially halt the growth of cannabis. Accordingly, application of these PGRs in combination may be utilised to restrict cannabis height without compromising yield within commercial cultivation.

Iron nanoparticles in combination with other conventional Fe sources remediate mercury toxicity-affected plants and soils by nutrient accumulation in bamboo species

The issue of mercury (Hg) toxicity has recently been identified as a significant environmental concern, with the potential to impede plant growth in forested and agricultural areas. Conversely, recent reports have indicated that Fe, may play a role in alleviating HM toxicity in plants. Therefore, this study's objective is to examine the potential of iron nanoparticles (Fe NPs) and various sources of Fe, particularly iron sulfate (Fe SO4 or Fe S) and iron-ethylene diamine tetra acetic acid (Fe - EDTA or Fe C), either individually or in combination, to mitigate the toxic effects of Hg on Pleioblastus pygmaeus. Involved mechanisms in the reduction of Hg toxicity in one-year bamboo species by Fe NPs, and by various Fe sources were introduced by a controlled greenhouse experiment. While 80 mg/L Hg significantly reduced plant growth and biomass (shoot dry weight (36%), root dry weight (31%), and shoot length (31%) and plant tolerance (34%) in comparison with control treatments, 60 mg/L Fe NPs and conventional sources of Fe increased proline accumulation (32%), antioxidant metabolism (21%), polyamines (114%), photosynthetic pigments (59%), as well as root dry weight (25%), and shoot dry weight (22%), and shoot length (22%). Fe NPs, Fe S, and Fe C in plant systems substantially enhanced tolerance to Hg toxicity (23%). This improvement was attributed to increased leaf-relative water content (39%), enhanced nutrient availability (50%), improved antioxidant capacity (34%), and reduced Hg translocation (6%) and accumulation (31%) in plant organs. Applying Fe NPs alone or in conjunction with a mixture of Fe C and Fe S can most efficiently improve bamboo plants' tolerance to Hg toxicity. The highest efficiency in increasing biochemical and physiological indexes under Hg, was related to the treatments of Fe NPs as well as Fe NPs + FeS + FeC. Thus, Fe NPs and other Fe sources might be effective options to remove toxicity from plants and soil. The future perspective may help establish mechanisms to regulate environmental toxicity and human health progressions.

Metabolic changes in tomato plants caused by psychrotolerant Antarctic endophytic bacteria might be implicated in cold stress mitigation.

Climate change is responsible for mild winters and warm springs that can induce premature plant development, increasing the risk of exposure to cold stress with a severe reduction in plant growth. Tomato plants are sensitive to cold stress and beneficial microorganisms can increase their tolerance. However, scarce information is available on mechanisms stimulated by bacterial endophytes in tomato plants against cold stress. This study aimed to clarify metabolic changes stimulated by psychrotolerant endophytic bacteria in tomato plants exposed to cold stress and annotate compounds possibly associated with cold stress mitigation. Tomato seeds were inoculated with two bacterial endophytes isolated from Antarctic Colobanthus quitensis plants (Ewingella sp. S1.OA.A_B6 and Pseudomonas sp. S2.OTC.A_B10) or with Paraburkholderia phytofirmans PsJN, while mock-inoculated seeds were used as control. The metabolic composition of tomato plants was analyzed immediately after cold stress exposure (4°C for seven days) or after two and four days of recovery at 25°C. Under cold stress, the content of malondialdehyde, phenylalanine, ferulic acid, and p-coumaric acid was lower in bacterium-inoculated compared to mock-inoculated plants, indicating a reduction of lipid peroxidation and the stimulation of phenolic compound metabolism. The content of two phenolic compounds, five putative phenylalanine-derived dipeptides, and three further phenylalanine-derived compounds was higher in bacterium-inoculated compared to mock-inoculated samples under cold stress. Thus, psychrotolerant endophytic bacteria can reprogram polyphenol metabolism and stimulate the accumulation of secondary metabolites, like 4-hydroxybenzoic and salicylic acid, which are presumably involved in cold stress mitigation, and phenylalanine-derived dipeptides possibly involved in plant stress responses.

Seed pretreatment with brassinosteroids stimulates sunflower immunity against parasitic weed (Orobanche cumana) infection.

Broomrape (Orobanche cumana) negatively affects sunflower, causing severe yield losses, and thus, there is a need to control O. cumana infestation. Brassinosteroids (BRs) play key roles in plant growth and provide resilience to weed infection. This study aims to evaluate the mechanisms by which BRs ameliorate O. cumana infection in sunflower (Helianthus annuus). Seeds were pretreated with BRs (1, 10, and 100 nM) and O. cumana inoculation for 4 weeks under soil conditions. O. cumana infection significantly reduced plant growth traits, photosynthesis, endogenous BRs and regulated the plant defence (POX, GST), BRs signalling (BAK1, BSK1 to BSK4) and synthesis (BRI1, BR6OX2) genes. O. cumana also elevated the levels of malondialdehyde (MDA), hydroxyl radical (OH-), hydrogen peroxide (H2O2) and superoxide (O2 •-) in leaves/roots by 77/112, 63/103, 56/97 and 54/89%, as well as caused ultrastructural cellular damages in both leaves and roots. In response, plants activated a few enzymes, superoxide dismutase (SOD), peroxidase (POD) and reduced glutathione but were unable to stimulate the activity of ascorbate peroxidase (APX) and catalase (CAT) enzymes. The addition of BRs (especially at 10 nM) notably recovered the ultrastructural cellular damages, lowered the production of oxidative stress, activated the key enzymatic antioxidants and induced the phenolic and lignin contents. The downregulation in the particular genes by BRs is attributed to the increased resilience of sunflower via a susceptible reaction. In a nutshell, BRs notably enhanced the sunflower resistance to O. cumana infection by escalating the plant immunity responses, inducing systemic acquired resistance, reducing oxidative or cellular damages, and modulating the expression of BR synthesis or signalling genes.

The most relevant drought-tolerant indices for selecting barley drought-tolerant genotypes

During its development cycle, lack of water is one of the factors reducing plant growth and yields, in the world's arid regions. The identification of indices that characterize the most tolerant genotypes to drought is very useful since it allows us to evaluate the tolerance of large varieties collections within a short and early stage. This study aimed to identify the most efficient drought tolerance indicators and evaluate, from the early stage of plant development, the germination parameters that would be correlated with drought tolerance in the field. If such correlations were identified, it would be possible to screen dozens of genotypes in the laboratory and identify the most tolerant ones before moving into the field. To attain this objective, two tests were carried out: The first one was realized in the laboratory to assess some germination parameters (germination rate, root length, root number, etc.) of sixteen North African barley genotypes (Algerians, Tunisians, and Egyptians) at the germination stage, under polyethylene glycol (PEG-6000) induced stress. The second test was carried out in the field to measure the grain yield of the same genotypes, under favorable and limited water conditions. The laboratory test revealed significant differences between root lengths (RL) of different genotypes within each water regime and between different treatments (control and PEG-6000 solution). The obtained result showed the superiority of most Egyptian genotypes, especially under stress conditions induced by PEG-6000. The field trial also showed significant differences in grain yields under both water regimes (stressful and non-stressful regimes) and pointed to the high performance of the majority of Egyptian genotypes. The calculated indices [(STI), (SSI), (YSI), and (TOL)] showed variable correlations depending on the index used and concluded that STI and YSI are the best indicators of drought tolerance compared to the others. Among the germination parameters, only the root length (RL) under PEG stress is positively correlated with grain yield, obtained under drought conditions in the field. Therefore, it would be possible to use this parameter to select, at an early stage, the most drought-tolerant genotypes.

Experimental Host and Vector Ranges of the Emerging Maize Yellow Mosaic Polerovirus.

Maize yellow mosaic virus (MaYMV) is an emerging polerovirus that has been detected in maize, other cereal crops, and weedy grass species in Asia, Africa, and the Americas. Disease symptoms in maize include prominent leaf tip reddening and stunting. Infection by MaYMV has been reported to reduce plant growth and yields by 10 to 30% in some instances. In this study, an experimental host range for MaYMV among agronomically important cereal crops and common grasses was established. Additional aphid species were assessed as potential vectors for MaYMV, and their transmission efficiencies were determined. Here, we report oats, foxtail millet, barley, and rye as new experimental cereal crop hosts of MaYMV in addition to confirming the previously reported hosts of corn, sorghum, wheat, and broom millet. Four of the nine other grass species evaluated were also identified as suitable experimental hosts for MaYMV: ryegrass, switchgrass, green foxtail, and sand love grass. Interestingly, no visible symptoms were present in any of the infected hosts besides the susceptible maize control. Vector range studies identified the greenbug aphid Schizaphis graminum as a new vector of MaYMV, though transmission efficiency was lower than the previously reported Rhopalosiphum maidis vector and similar to the other known aphid vector R. padi. Given MaYMV's global ubiquity, ability to evade detection, and broad host range, further characterization of yield impacts and identification of viable control strategies are desirable.

Putting Biochar in Action: A Black Gold for Efficient Mitigation of Salinity Stress in Plants. Review and Future Directions.

Soil salinization is a serious concern across the globe that is negatively affecting crop productivity. Recently, biochar received attention for mitigating the adverse impacts of salinity. Salinity stress induces osmotic, ionic, and oxidative damages that disturb physiological and biochemical functioning and nutrient and water uptake, leading to a reduction in plant growth and development. Biochar maintains the plant function by increasing nutrient and water uptake and reducing electrolyte leakage and lipid peroxidation. Biochar also protects the photosynthetic apparatus and improves antioxidant activity, gene expression, and synthesis of protein osmolytes and hormones that counter the toxic effect of salinity. Additionally, biochar also improves soil organic matter, microbial and enzymatic activities, and nutrient and water uptake and reduces the accumulation of toxic ions (Na+ and Cl), mitigating the toxic effects of salinity on plants. Thus, it is interesting to understand the role of biochar against salinity, and in the present Review we have discussed the various mechanisms through which biochar can mitigate the adverse impacts of salinity. We have also identified the various research gaps that must be addressed in future study programs. Thus, we believe that this work will provide new suggestions on the use of biochar to mitigate salinity stress.