Physiological and photochemical profiling of soybean plant using biological and chemical methods of treatment against biotic stress management.

Phyto-pathogenic fungal species is a leading biotic stress factor to agri-food production and ecosystem of globe. Chemical (Systemic fungicides) and biological treatment (micro-organism) are globally accepted methods that are being used against biotic stress (disease) management. Plant Growth-Promoting Microbes are being used as an alternative to ease chemical dependency as their overdoses have generated injurious effects on plants and environment. Therefore, present study performs to evaluate the photochemical and physiological profiling of plants exposed to chemical and biological treatment in biotic stress (disease) environment. Two concentrations of each chemical treatment i.e. Topsin-M 70 (Dimethyl 4,4'-o-phenylene bis 3-thioallaphanate, MF1 = 3 g kg-1 and MF2 = 6 g kg-1 seeds) and biological treatment i.e. Trichoderma harzianum strain Th-6 (MT1 = 106 spores mL-1and MT2 = 107 spores mL-1) were used in this experiment. Macrophomina phaseolina (MP) were used as biotic stress factor causing root rot disease in soybean plants. Morpho-physiological assessments and light harvesting efficiency of photosystem II were conducted after 52 days of treatment. Maximum quantum yield (Fv/Fm), number and size of active reaction center (Fv/Fo), photochemical quenching (qP), efficiency of photosystem II (ΦPSII), electron transport rate (ETR), chlorophyll content index (CCI), relative water content (RWC) and stomatal conductance (SC) were increased in MT2 and MF1 treatments as compared to stress plants (MP). Biological (MT2) and chemical (MF1) treatment lessen the production of stress markers showing -48.0 to -54.3% decline in malondialdehyde (MDA) and -42.0 to -53.7% in hydrogen peroxide (H2O2) as compared to stress plant (MP). Biological treatment in both concentration (MF1 & MF2) while chemical treatment at low dose effectively mitigates biotic stress and eases the magnitude of disease. Increasing doses of chemical treatment persuaded deleterious effects on the physiology and light harvesting efficiency of stressed plant suggesting the role of biological treatment (T. harzianum) against biotic stress management in future of crop protection.

Halophilic soil microbial strains improve the moisture stress tolerance in oilseed crop by sustaining Photosystem II functionality.

The sunflower (Helianthus annus L.) is a vital oilseed crop exposed to drought globally. A vast proportion of research is devoted to the naturally occurring microbes and their interaction with plants to alleviate stress consequences. Halophilic bacterial strains, i.e., Bacillus cereus KUB-15 (accession number NR 074540.1), KUB-27 (accession number NR 074540.1), and Bacillus licheniformis strain AAB9 (accession number MW362506), were isolated. Later, isolated strains were used for sunflower through inoculation. Plants were allowed to grow, and thirty-days-old plants were exposed to fixed moisture stress (40-45%). The functionality of photosystem II, light-harvesting ability, and physiological tolerance of cultivars were examined. Bacterial strains B. licheniformis sustained substantial electron flow in between photosystem II (PS II) and photosystem I (PS 1) that not only favored the passable photosynthetic performance but also enhanced antioxidant enzyme activity under stress condition. Compared to other halophilic strains, Bacillus licheniformis did manage reasonable relative water content (RWC), chlorophyll content index (CCI) and biomass production under stress condition. In comparison to both sunflower cultivars, bacterial inoculation was greatly restored growth and photosynthetic performance in Agsun-5264 than S-278 under moisture stress environment. Hence, it is suggested that that bacterial strain and plants cultivar compatibility are essential aspect for sustainable agriculture production.

Recent progress in bio-mediated synthesis and applications of engineered nanomaterials for sustainable agriculture.

The ever-increasing demand for agricultural food products, medicine, and other commercial sectors requires new technologies for agricultural practices and promoting the optimum utilization of natural resources. The application of engineered nanomaterials (ENMs) enhance the biomass production and yield of food crop while resisting harmful environmental stresses. Bio-mediated synthesis of ENMs are time-efficient, low-cost, environmentally friendly, green technology. The precedence of using a bio-mediated route over conventional precursors for ENM synthesis is non-toxic and readily available. It possesses many active agents that can facilitate the reduction and stabilization processes during nanoparticle formation. This review presents recent developments in bio-mediated ENMs and green synthesis techniques using plants, algae, fungi, and bacteria, including significant contributions to identifying major ENM applications in agriculture with potential impacts on sustainability, such as the role of different ENMs in agriculture and their impact on different plant species. The review also covers the advantages and disadvantages of different ENMs and potential future research in this field.

Scrutinizes the Sustainable Role of Halophilic Microbial Strains on Oxygen-Evolving Complex, Specific Energy Fluxes, Energy Flow and Nitrogen Assimilation of Sunflower Cultivars in a Suboptimal Environment.

Environmental extremes such as hypersaline conditions are significant threats to agricultural productivity. The sustainable use of halophilic microbial strains was evaluated in plant in a salt stress environment. Oxygen-evolving complex (OEC), energy compartmentalization, harvesting efficiencies (LHE), specific energy fluxes (SEF), and nitrogen assimilation of oilseed crops (Sunflower cultivars) in a suboptimal environment was examined. Plants were grown in a plastic pot (15 ×18 cm2) containing sterilized (autoclaved at 120°C for 1 h) soil. Twenty-five ml suspension (107 CFU/ml) each of Bacillus cereus strain KUB-15 and KUB-27 (accession number NR 074540.1) and Bacillus licheniformis strain AAB9 (accession number MW362506), were applied via drenching method. Month-old plants were subjected to salt stress via gradual increment method. The energy compartmentalization of microbial inoculated plants exposed to salt stress revealed higher photosystem II (PSII) activity at the donor side, lesser photo-inhibition, and increased performance of oxygen-evolving complex compared to control. High potassium (K+) and low sodium (Na+) ions in treated leaves with the activated barricade of the antioxidant system stimulated by Bacillus strains favored enhanced photochemical efficiency, smooth electron transport, and lesser energy dissipation in the stressed plants. Moreover, the results reveal the increased activity of nitrite reductase (NiR) and nitrate reductase (NR) by microbial inoculation that elevated the nitrogen availability in the salt-stressed plant. The current research concludes that the application of bio-inoculants that reside in the hyper-saline environment offers substantial potential to enhance salt tolerance in sunflowers by modulating their water uptake, chlorophyll, nitrogen metabolism, and better photochemical yield.

Profiling of energy compartmentalization in photosystem II (PSII), light harvesting complexes and specific energy fluxes of primed maize cultivar (P1429) under salt stress environment.

Photosystem II efficiency is the most important aspect of stress physiology to keep photosynthetic momentum operative under stress conditions. In the last few decades effect of priming on the germination growth and physiology of plants were highlighted. Profiling energy compartmentalization in PSII using chlorophyll fluorescence kinetics and specific energy fluxes of primed seeds and plants has not been documented. It is crucial to discover the changes associated with the light-harvesting complexes, PSII functionality, and photochemical modulations occurring in the biochemical thylakoid membrane in response to priming and salt stress. The present study mainly focuses on photosystem II efficiency leading to physiological tolerance by seed priming. We grow the plants after seed priming with the solution of sodium chloride (75 and 150 mM), salicylic acid (1 and 2 mM), and calcium chloride (34 mM) and nitrate (20 mM). All the primed plants were subjected to salt stress 10 days after germination @ 0, 75, and 150 mM NaCl. Later germination, growth, morphology, physiology, PS II functionality and photochemical yield were evaluated. NaCl priming did more promising effects on energy compartmentalization, light-harvesting ability, and specific energy fluxes of photosystem II compared to salicylic acid and calcium salts under a stress environment. Maximum quantum yield (FV/FM), active reaction centers with higher efficiency of water splitting complex (FV/FO), restored electron flow, higher photochemical quenching (qP), oxygen evolution (SMT-phase), and almost negligible heat dissipation are associated with better osmotic adjustment and higher water uptake (RWC) under stress condition.

Physiological and photochemical evaluation of pepper methionine sulfoxide reductase B2 (CaMsrB2) expressing transgenic rice in saline habitat.

Two pepper methionine sulfoxide reductase B2 (CaMsrB2) gene expressing transgenic rice lines (L-8 and L-23) were interrogated with respect to their physiological and photochemical attributes along with control (WT, Ilmi) as a standard against varying levels of salt concentration which are 75 mM, 150 mM and 225 mM. Against various levels of salt (NaCl) concentration, recurring detrimental effects of extreme salt stress was observed and more pronounced in the wild type plants as compared to our transgenic lines. As the exacerbated effects of salinity is responsible for pushing the plants to their ecological tolerance, our transgenic lines performed well uplifted in different realms of physiology and photochemistry such as relative water content (RWC = 60-75%), stomatal conductance (gs = 70-190 mmolm-2s-1), performance index (PIABS = 1.0-4.5), maximal photochemical yield of PSII (FV/FM = 0.48-0.72) and chlorophyll content index (CCI = 5-7.2 au) in comparison to the control. Relative gene expression, ion analysis and antioxidants activity were analyzed in all treatments to ensure the hypothesis obtained from data of physiology and photochemistry. Photosynthetic apparatus is known to lose energy in various forms such as NPQ, DIO/CS, damages of reaction center (FV/FO) which are the markers of poor health were clearly decreased in the L-23 line as compared to L-8 and WT. Present study revealed the protruding tolerance of L-23 and L-8 transgenic lines with L-23 line in the lead in comparison to control and L-8 transgenic lines.

Physiological Aspects of Germination and Early Seedling Establishment of Pleurotus sajor-caju Glyceraldehyde-3-Phosphate Dehydrogenase Expressing Transgenic Rice in Saline Environment.

GPD encodes glyceraldehyde-3-phosphate dehydrogenase enzyme involved in sugar mobilization, particularly glycolysis and gluconeogenesis. The objective of this study was to determine physiological aspects of germination and early seedling establishment of PsGPD (Pleurotus sajor-caju glyceraldehyde-3-phosphate dehydrogenase) expressing transgenic rice (T5) against different salt concentrations. The T5 line that carried 2 copies of T-DNA and had the highest level of PsGPD expression was used in the investigation. Final germination percentage, amylase activity, reducing sugar accumulation, and chlorophyll biosynthesis were comparatively higher in PsGPD expressing transgenic rice against elevating saline conditions. A slow-paced conversion of porphyrin's precursors was seen through the matrix model and further elaborated by a graphical model. A sustained level of porphyrin was observed in PsGPD expressing transgenic rice. These data were concurrent with the relative gene expression and thermal imaging (thermography) of PsGPD expressing transgenic rice against salt stress. Morphological attributes also favored the salt tolerance exhibited by PsGPD-transformed rice.

Scrutinizing the Application of Saline Endophyte to Enhance Salt Tolerance in Rice and Maize Plants.

The present study aimed to witness the plant-microbe interaction associated with salt tolerance in crops. We isolated the endophytic microbe from the root zone of halophytic grass. Later, the salt tolerance of the endophyte was tested in the saline medium and was identified using nucleotide sequencing (GenBank under the accession numbers: SUB9030920 AH1_AHK_ITS1 MW570850: SUB9030920 AH1_AHK_ITS4 MW570851). Rice and maize seeds were coated with identified endophyte Aspergillus terreus and were sown in separate plastic pots. Later 21-day-old seedlings were subjected to three NaCl concentrations, including 50, 100, and 150 mM salt stress. Under saline conditions, A. terreus showed a substantial increase in growth, biomass, relative water content, oxidative balance, and photochemical efficiency of rice and maize plants. The data reflected that the stimulation of gibberellic acid (GA) in treated leaves may be the main reason for the upregulation of photosynthesis and the antioxidant defense cascade. The data also depict the downregulation of oxidative damage markers malondialdehyde, hydrogen peroxide in rice and maize plants. Conclusively, salt-tolerant endophytic fungus A. terreus explicitly displayed the positive plant-microbe interaction by developing salt tolerance in rice and maize plants. Salt tolerance by endophytic fungus coincides with the enhanced GA concentration, which illustrated the stimulated physiological mechanism and gene in response to the extreme environmental crisis, resulting in improved crop productivity.

Over-expression of PsGPD, a mushroom glyceraldehyde-3-phosphate dehydrogenase gene, enhances salt tolerance in rice plants.

Transgenic potatoes expressing glyceraldehyde-3-phosphate dehydrogenase (GPD), isolated from the oyster mushroom, Pleurotus sajor-caju, had increased tolerance to salt stress (Jeong et al. Biochem Biophys Res Commun 278:192-196, 2000). To examine the physiological mechanisms enhancing salt tolerance in GPD-transgenic rice plants, the salt tolerance of five GPD transgenic rice lines (T1-T5) derived from Dongjin rice cultivar were evaluated in a fixed 150 mM saline environment in comparison to two known wild-type rice cultivars, Dongjin (salt sensitive) and Pokali (salt tolerant). Transgenic lines, T2, T3, and T5, had a substantial increase in biomass and relative water content compared to Dongjin. Stomatal conductance and osmotic potential were higher in the GPD transgenic lines and were similar to those in Pokali. The results are discussed based on the comparative physiological response of GPD transgenic lines with those of the salt-sensitive and salt-tolerant rice cultivars.