The role of silicon in mitigating the incidence and damage of yellow stem borer in rice crops is well proven. However, the underlying mechanisms offered by silicon amendment in rice crops against yellow stem borer were not explored or poorly understood. Here, we have shown that silicon supplement to rice plants at 200 mg/kg of soil, improved silicification in stem tissues by increased length, width (18.1-32.5%), and area (6.6-14.2%) of silica cells and silicon content given over scanning electron microscopy and electron-dispersive spectrophotometric analysis. The increased activities of antioxidant and defense enzymes such as catalase (106-215%), superoxide dismutase (74.5%), peroxidase (52.1%), phenylalanine ammonia lyase (74%), and polyphenol oxidase (47.3%) in rice plants supplemented with silicon and infested with yellow stem borer at different durations were shown. The enhanced concentrations of total sugars (23.6%) and total phenols (18.4%) were also observed due to silicon supplement to rice plants. However, the defense enzyme activities were less in rice plants without silicon supplementation and yellow stem borer infestation. The outcome of the study highlighted the impact of silicon in activating the defense responses in rice plants infested with yellow stem borer. Silicon supplementation should be considered as one of the alternative and sustainable measures for integrated management of yellow stem borer in rice across ecosystems.
Salinity is a major abiotic stress that negatively affects agricultural land, significantly reducing crop yields. It alters the fundamental structure of the soil, causing a decrease in porosity, reduced aeration, and impaired water movement. Piriformospora indica, multifaceted fungi can enhance plant tolerance under abiotic stress conditions. The present study examined the effects of Piriformospora indica on the growth of Solanum melongena L. under saline conditions in a greenhouse, assessing parameters such as proline accumulation, lipid peroxidation, chlorophyll content, stomatal behavior, antioxidant activity, and phenotypic traits under salt stress Results of the present study showed significant improvement in phenotypic traits of Piriformospora indica colonized plants under saline conditions. Solanum melongena L. plants treated with 200 mM NaCl had swollen, deformed guard cells and closed stomata, while colonized plants maintained normal stomatal structure and their stomata remained open. Additionally, untreated plants exhibited higher malondialdehyde levels, indicating greater lipid peroxidation, while Piriformospora indica-colonized plants showed reduced oxidative damage, increased chlorophyll content, and enhanced peroxidase activity under saline conditions. The salt tolerance mediated by Piriformospora indica likely involves lipid desaturation, activation of antioxidant enzymes to counter reactive oxygen species, enhanced metabolism, improved nutrient uptake, proline accumulation, and increased phytohormone production.
High-Density Polyethylene (HDPE) PE is one of the primary contributors of long-lasting and prolonged pollution in the environment. In this study, more than three hundred marine isolates collected off the Gujarat Sea coast were tested for HDPE plastic utilizing ability. Among fifty-one positive noted isolates, RS124 as a potential strain was identified as Micrococcus flavus (accession is PP858228) based on 16 S rRNA gene sequencing and total cellular fatty acid profiling. Initial bacterial adherence on the film surface was shown in a scanning electron microscopy (SEM) image as a key step to biodegradation. Moreover, atomic force microscopy (AFM) shows that the film surface became more fragile, damaged, and rougher than untreated films. Shifts and alterations in peak transmittance with emergence of two new shouldered peak in degraded HDPE observed by fourier transform infrared spectroscopy (FTIR) was associated to chemical and mechanical alteration. Thermogravimetric analysis (TGA) analysis designated larger difference in percent weight loss provisions thermal instability. In the enzymatic study, the highest activity of peroxidase and dehydrogenase was recorded on the 3rd and 4th weeks of treatment with strain, respectively, during co-incubation. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis disclosed the presence of a distinct 19 kDa size protein, uncovering its role in the colonization of bacteria on the hydrophilic HDPE surfaces. About 1.8% weight reduction in HDPE was recorded as a result after 30 days of bio-treatment with M. flavus. Hence, the entire observed results reveal that the M. flavus RS124 could be effectively applied for the degradation of HDPE. This is the first report on M. flavus that it exhibits plastic degrading characteristic ever, which may allow for green scavenging of plastic waste.
Heavy metal pollution reduces the community of soil microorganisms, including fungi from the genus Trichoderma, which are plant growth promotors and biological control agents. Because of potential effects on crop productivity, the toxic effects of heavy metals (HMs) in Trichoderma are of interest. However, there have been few studies on the biochemical and molecular response to oxidation caused by exposure to copper (Cu), chromium (Cr), and lead (Pb) and whether this antioxidant response is species-specific. In this study, we compared the tolerance of Trichoderma asperellum and Trichoderma longibrachiatum to Cu, Pb, and Cr and evaluated the expression of genes related to the antioxidant response, including glutathione peroxidase (GPX), catalase (CAT), and cysteine synthase (CYS) as well as the activity of peroxidase and catalase. The isolates of Trichoderma were selected because we previously reported them as promotors of plant growth and agents of biological control. Our results revealed that, with exposure to the three HMs, the Trichoderma cultures formed aggregates and the culture color changed according to the metal and the Trichoderma species. The tolerance index (TI) indicated that the two Trichoderma species were tolerant of HMs (Cu > Cr > Pb). However, the TI and conidia production revealed that T. longibrachiatum was more tolerant of HMs than T. asperellum. The three HMs caused oxidative damage in both Trichoderma species, but the enzyme activity and gene expression were differentially regulated based on exposure time (72 and 144 h) to the HMs and Trichoderma species. The main changes occurred in T. asperellum; the maximum expression of the GPX gene occurred at 144 h in response to all three HMs, whereas the CAT gene was upregulated at 72 h in response to Cu but downregulated at 144 h in response to all three HMs. The CYS gene was upregulated in response to the three metals. The peroxidase activity increased with all three HMs, but the catalase activity increased with Cu and Pb at 72 h and decreased at 144 h with Pb and Cr. In T. longibrachiatum, the GPX gene was upregulated with all three HMs at 72 h, the CAT gene was upregulated only with Pb at 72 h and was downregulated at 144 h with HMs. Cr and Cu upregulated CYS gene expression, but expression did not change with Pb. The peroxidase activity increased with Cu at 144 h and with Cr at 72 h, whereas Pb decreased the enzyme activity. In contrast, catalase activity increased with the three metals at 144 h. In conclusion, T. longibrachiatum was more tolerant of Cu, Cr, and Pb than was T. asperellum, but exposure to all three HMs caused oxidative damage to both Trichoderma species. Peroxidases and catalases were activated, and the expression of the genes GPX and CYS was upregulated, whereas the CAT gene was downregulated. These findings indicate that the antioxidant response to HMs was genetically modulated in each Trichoderma species.
Antioxidant complex enzymes have a significant role in cellular homeostasis control in plants, and they inhibit the toxic action of reactive oxygen species when they are in excess. There are many antioxidant enzymes executing this role; among these, superoxide dismutase, catalase, and ascorbate peroxidase are reported as the most studied in this process, as they prevent free radicals from becoming more reactive and toxic to cells. Thus, this research was conducted to evaluate antioxidant enzyme expression in response to hydric stress at the reproductive stage in upland rice genotypes. Three genotypes from the upland rice breeding program on agreement between UFLA, EPAMIG, and EMBRAPA, CMG2093, CMG2172, and BRSMG Relampago, were used as controls. Genotypes were grown under field conditions with supplementary irrigation during the whole crop cycle, and hydric stress was induced in the reproductive phase before panicle emission. Seedlings were used in enzyme analyses from the emergence test and IVE on substrate (soil+sand at a 2:1 rate) at 70% and 10% field capacity. Significant differences were observed among genotypes for vigor tests. In biochemical tests, the CMG2093 genotype had lower damage on hydric deficit, with the best performance under hydric restriction conditions, being considered tolerant for this stress type.
Antioxidant responses play a crucial role in combating free radical damage induced by drought stress. In guar plants, the antioxidant mechanism is crucial for stress tolerance; however, the specific antioxidant response in individual guar genotypes remains unclear. This study investigates the physiological, biochemical, and transcriptional responses of four guar genotypes to drought stress by maintaining soil moisture content (SMC) at varying levels: control (100% FC), medium (60% FC), and severe (20% FC). Among the genotypes examined, HG-563 and HG-365 exhibit higher leaf relative water content (RWC) and total chlorophyll/carotenoid content, indicating lesser inhibition under drought stress compared to HG-75 and RGC-936. Notably, HG-563 and HG-365 demonstrate a significant increase in activities of key antioxidant enzymes such as superoxide dismutase (SOD), peroxidase (POD), ascorbate (AsA), and glutathione (GSH) during medium and severe drought stress conditions. This observation is further supported by in-gel activity assays revealing a notable upregulation of Cu/ZnSOD and POD isozymes, which is consistent with higher expression levels of Cu/ZnSOD and POD genes at the transcriptional level. Consequently, these results highlight the comparatively higher drought tolerance of HG-563 and HG-365 genotypes. The findings shed light on the activation of antioxidant responses in drought-tolerant guar genotypes under stress conditions, emphasizing the crucial role of antioxidant enzymes in the drought tolerance mechanism of guar plants.
Platycladus orientalis (P. orientalis) is a common tree used for vegetation restoration in northern China, and its large area propagation helps to improve site conditions. However, under harsh conditions such as poor land, the survival rate of P. orientalis is very low. Numerous studies have shown that root pruning can promote the formation of lateral roots in seedlings, enhancing the roots' capacity to absorb soil nutrients and water, and thereby improving the survival rate of seedlings. In this study, a one-third root pruning treatment was applied to P. orientalis seedlings, and the whole transcriptome of seedlings subjected to both control (CK) and root pruning treatments was sequenced to analyze their gene expression profiles. This study investigated the regulatory mechanisms of lateral root development in response to root pruning damage at the molecular level. Using nine cells, 15.28 Gb of clean data were obtained, which yielded 101,688 high-quality full-length transcript sequences and 22,955 low-quality full-length transcript sequences after clustering. Redundancy was then removed using CD-HIT, and Illumina RNA-seq sequencing produced 139.26 Gb of clean data. A total of 2025 differentially expressed genes (DEGs) were identified at three time points following root pruning treatment. Enrichment analysis revealed that the peroxidase gene family plays a significant role in lateral root proliferation. Furthermore, the expression levels of the peroxidase gene family were notably upregulated in comparison to the control group. Pathway enrichment analysis identified 22 relevant genes, which appeared to be highly associated with root growth and resilience to stress. Through examining the expression patterns and correlations of these genes, five central genes emerged as key players. The findings of this research suggest that the peroxidase gene family plays a crucial role in the stress response and root development of P. orientalis, providing reference and guidance for root development in other plant species.
Globally, soil acidification is a serious environmental issue that reduces commercial agricultural production. Rice is subjected to nutritional stress due to acidic soil, which is a major impediment to rice production. Since acid soil threatens rice plants with soil compaction, nutrient loss, and plant stress-induced oxidative cell damage that results in affecting the photosynthetic system, restricting the availability of water, and reducing overall plant growth and productivity. Since contemporary soil acidification management strategies provide mediocre results, the use of Sargassum wightii seaweed-based biostimulants (BS) and soil amendments is sought as an environmentally friendly alternative strategy, and therefore its potential isevaluated in this study. BS was able to mediate soil quality by improving soil pH and structure along with facilitating nitrogen phytoavailability. BS also increased the activity of the antioxidant enzyme system, superoxide dismutase ((48%), peroxidase (76.6%), and ascorbate peroxidase (63.5%), aggregating the monaldehyde-mediating accumulation of osmoprotective proline in roots, that was evident from rapid initiation of root hair growth in treated seedlings. BS was also able to physiologically modulate photosynthetic activities and chlorophyll production (24.31%) in leaves, maintaining the efficiency of plant water use by regulating the stomatal conductance (0.91 mol/m/s) and the transpiration rate (13.2 mM/m/s). The BS compounds were also successful in facilitating nitrogen uptake resulting in improved plant growth (59%), tiller-panicle number, and yield (52.57%), demonstrating a resourceful nitrogen use efficiency (71.96%) previously affected by stress induced by acid soil. Therefore, the study affirms the competent potential of S. wightii-based soil amendment to be applied not only to improve soil quality, but also to increase plant production and yield.
Plastic pollution is a common concern of global environmental pollution. Polystyrene (PS) and polyethylene (PE) account for almost one-third of global plastic production. However, so far, there have been few reports on microbial strains capable of simultaneously degrading PS and PE. In this study, Microbacterium esteraromaticum SW3, a non-pathogenic microorganism that can use PS or PE as the only carbon source in the mineral salt medium (MM), was isolated from plastics-contaminated soil and identified. The optimal growth conditions for SW3 in MM were 2% (w/v) PS or 2% (w/v) PE, 35 degrees C and pH 6.3. A large number of bacteria and obvious damaged areas were observed on the surface of PS and PE products after inoculated with SW3 for 21 d. The degradation rates of PS and PE by SW3 (21d) were 13.17% and 5.39%, respectively. Manganese peroxidase and lipase were involved in PS and PE degradation by SW3. Through Fourier infrared spectroscopy detection, different functional groups such as carbonyl, hydroxyl and amidogen groups were produced during the degradation of PS and PE by SW3. Moreover, PS and PE were degraded into alkanes, ketones, carboxylic acids, esters and so on detected by GC-MS. Collectively, we have isolated and identified SW3, which can use PS or PE as the only carbon source in MM as well as degrade PS and PE products. This study not only provides a competitive candidate strain with broad biodegradability for the biodegradation of PS and/or PE pollution, but also provides new insights for the study of plastic biodegradation pathways.
Salt stress is one of the most damaging environmental stresses of recent times and poses a significant threat to food security. Here, we conducted an experimental study over two consecutive years (2022-2023) to evaluate the physiological and biochemical characteristics of kidney beans. The study used a randomized complete block design with 4 replications (n = 4). The experiment included three levels of salicylic acid (SA): SA0 (0 mM), SA0.5 (0.5 mM) and SA1 (1 mM). The study also used biochar in four levels, without biochar as the control treatment (B0), regular biochar (Rb) by 2.5 % per soil weight, modified biochar with phosphoric acid (PA) by 1.25 % per soil weight, and modified biochar with sulfuric acid (Sb) by 1.25 % per soil weight. Additionally, salt stress (SS) was induced using NaCl in three levels, SS0 (distilled water), SS4 (4 4 dS m-1), and SS8 (8 dS m-1). The results showed that salt stress, biochar, and salicylic acid significantly affected the measured parameters. Salt stress (SS4 and SS8) negatively affected the measured parameters compared to the control. However, the application of biochar and salicylic acid regulated the alleviation of the impact of salt stress. Under SS4, the application of Rb along with SA1 resulted in the highest value of proline content. The highest enzymatic activity of catalase was observed due to the use of PA in combination with SA0.5 under non -saline soil conditions. The use of PA under SS8 increased the hydrogen peroxide and caused the highest activity, while the lowest activity was obtained under non -saline soil conditions with the application of Sb. In the first year of the experiment, it was found that the use of SA1 without biochar under non -stress conditions resulted in the highest levels of malondialdehyde. Likewise, in the second year, the highest malondialdehyde activity was observed by applying Rb and SA1 under SS8. The research concludes that kidney bean plants are significantly impacted by salt stress, which affects their biochemical characteristics. Nonetheless, the combined application of biochar and salicylic acid showed promise in addressing these challenges. This approach could be particularly effective in managing salinity issues in arid and semi -arid regions, highlighting the potential of biochar and salicylic acid for improving plant resilience under such conditions.