Ectomycorrhiza and ethylenediurea reduced the impact of high nitrogen and ozone stresses and increased the growth of Cedrus deodara.

Cedrus deodara is the central conifer plant affected by ozone and nitrogen pollutants among forest species worldwide. The growth of C. deodara depends upon the ectomycorrhizal (ECM) association, which is usually disturbed by these factors. This study aims to understand how these factors affect plants at physiological and biochemical levels. Three fungal strain consortiums were inoculated with two-year-old C. deodara seedlings. The stresses of 100 kg N h-1and 100 ppb O3 were applied for six months to study their impact on chlorophyll and antioxidant enzymes (SOD, CAT, and APX). The results showed that C2 (Consortium of Cedrus deodara) positively impacted the growth of selected plant species. The high photosynthesis rate was determined by enhanced chlorophyll content, and C2-treated plants showed high chlorophyll content. Relatively, chlorophyll a and b contents increased significantly in the seedlings treated with Ethylenediurea (EDU) alone and with ozone stress. In addition, a significant difference was observed between EDU and O3-treated plants (14% EDU400-O3 and 23% EDU600-O3) and the control. Overall, antioxidant activities were higher in the treated samples than in the control. The order of SOD activity was C2 (448 U/gFW) and lowest (354.7 U/gFW) in control. APX also showed higher activity in treated plants in C1 ≥ C2 ≥ C3+O3, whereas CAT activity was the highest in C2 treatments. Ozone and nitrogen-stressed plants showed higher activities than EDU-treated plants compared to non-treated ones. Our findings highlight the importance of understanding the signaling effects of numerous precursors. Moreover, an extended investigation of seedlings developing into trees must be conducted to verify the potential of ectomycorrhizal strains associated with C. deodara and comprehend EDU's role as a direct molecular scavenger of reactive toxicants.

Optimizing chili production in drought stress: combining Zn-quantum dot biochar and proline for improved growth and yield.

The reduction in crop productivity due to drought stress, is a major concern in agriculture. Drought stress usually disrupts photosynthesis by triggering oxidative stress and generating reactive oxygen species (ROS). The use of zinc-quantum dot biochar (ZQDB) and proline (Pro) can be effective techniques to overcome this issue. Biochar has the potential to improve the water use efficiency while proline can play an imperative role in minimization of adverse impacts of ROS Proline, functioning as an osmotic protector, efficiently mitigates the adverse effects of heavy metals on plants by maintaining cellular structure, scavenging free radicals, and ensuring the stability of cellular integrity. That's why current study explored the impact of ZQDB and proline on chili growth under drought stress. Four treatments, i.e., control, 0.4%ZQDB, 0.1 mM Pro, and 0.4%ZQDB + Pro, were applied in 4 replications following the complete randomized design. Results exhibited that 0.4%ZQDB + Pro caused an increases in chili plant dry weight (29.28%), plant height (28.12%), fruit length (29.20%), fruit girth (59.81%), and fruit yield (55.78%) over control under drought stress. A significant increment in chlorophyll a (18.97%), chlorophyll b (49.02%), and total chlorophyll (26.67%), compared to control under drought stress, confirmed the effectiveness of 0.4%ZQDB + Pro. Furthermore, improvement in leaves N, P, and K concentration over control validated the efficacy of 0.4%ZQDB + Pro against drought stress. In conclusion, 0.4%ZQDB + Pro can mitigate drought stress in chili. More investigations are suggested to declare 0.4%ZQDB + Pro as promising amendment for mitigation of drought stress in other crops as well under changing climatic situations.

Removal of Antibiotic Resistance Genes, Class 1 Integrase Gene and Escherichia coli Indicator Gene in a Microalgae-Based Wastewater Treatment System.

Microalgae-based wastewater treatment systems (AWWTS) have recently shown promise in the mitigation of antibiotic resistance genes (ARGs) from municipal wastewater (MWW). However, due to the large number of ARGs that exist in MWW, the use of indirect conventional water quality parameters to monitor ARGs reduction in wastewater would make the process less burdensome and economically affordable. In order to establish a robust relationship between the ARGs and water quality parameters, the current study employed different microalgae strains in monoculture (CM2, KL10) and multi-species combinations (CK and WW) for the MWW treatment under outdoor environmental conditions. The studied genes were quantified in the MWW influents and effluents using real-time PCR. All the cultures substantially improved the physicochemical qualities of the MWW. Out of the 14 genes analyzed in this study, tetO, tetW, tetX and ermB were decreased beyond detection within the first 4 days of treatment in all the cultures. Other genes, including blaCTX, sul1, cmlA, aadA, int1 and uidA were also decreased beyond a 2 log reduction value (LRV). The mobile genetic element, int1, correlated positively with most of the ARGs, especially sul1 (r ≤ 0.99, p < 0.01) and aadA (r ≤ 0.97, p < 0.01). Similarly, the Escherichia coli indicator gene, uidA, correlated positively with the studied genes, especially with aadA, blaCTX, blaTEM and cmlA (r ≤ 0.99 for each, p < 0.01). Some of the studied genes also correlated positively with total dissolved solids (TDS) (r ≤ 0.98, p < 0.01), and/or negatively with total suspended solids (TSS) (r ≤ −0.98, p < 0.01) and pH (r ≤ −0.98, p < 0.01). Among the tested cultures, both monocultures, i.e., KL10 and CM2 were found to be more consistent in gene suppression than their multi-species counterparts. The findings revealed water quality parameters such as TDS, TSS and E. coli as reliable proxies for ARGs mitigation in AWWTS and further highlight the superiority of monocultures over multi-species cultures in terms of gene suppression from the MWW stream.

Novel microalgae strains from selected lower Himalayan aquatic habitats as potential sources of green products.

Microalgal biomass provides a renewable source of biofuels and other green products. However, in order to realize economically viable microalgal biorefinery, strategic identification and utilization of suitable microalgal feedstock is fundamental. Here, a multi-step suboptimal screening strategy was used to target promising microalgae strains from selected freshwaters of the study area. The resulting strains were found to be affiliated to seven closely-related genera of the family Scenedesmaceae, as revealed by both morphologic and molecular characterization. Following initial screening under upper psychrophilic to optimum mesophilic (irregular temperature of 14.1 to 35.9°C) cultivation conditions, superior strains were chosen for further studies. Further cultivation of the selected strains under moderate to extreme mesophilic cultivation conditions (irregular temperature of 25.7 to 42.2°C), yielded up to 74.12 mgL-1day-1, 19.96 mgL-1day-1, 48.56%, 3.34 µg/mL and 1.20 µg/mL, for biomass productivity, lipid productivity, carbohydrate content, pigments content and carotenoids content respectively. These performances were deemed promising compared with some previous, optimum conditions-based reports. Interestingly, the fatty acids profile and the high carotenoids content of the studied strains revealed possible tolerance to the stress caused by the changing suboptimal cultivation conditions. Overall, strains AY1, CM6, LY2 and KL10 were exceptional and may present sustainable, promising feedstock for utilization in large-scale generation of green products, including biodiesel, bioethanol, pigments and dietary supplements. The findings of this study, which exposed promising, eurythermal strains, would expand the current knowledge on the search for promising microalgae strains capable of performing under the largely uncontrolled large-scale cultivation settings.

Organic amendment plus inoculum drivers: Who drives more P nutrition for wheat plant fitness in small duration soil experiment.

Functioning of ecosystems depends on the nutrient dynamics across trophic levels, largely mediated by microbial interactions in the soil food web. The present study investigated the use of phosphate solubilizing bacteria (PSB) and poultry manure (PM) for maintaining labile P in the soil for an extensive fertility enhancement and as a substitution of chemical fertilizers. Based on the different P solubilizing capabilities of Bacillus and Pseudomonas, a quadruple consortium of Bacillus subtilis, Bacillus cereus, Bacillus thuringiensis and Pseudomonas fluorescens, and their grazer nematodes (soil free living) supplemented with PM were studied. This study was carried out on the trophic levels of soil communities to assess the growth and availability of P to the wheat plants. Experiment was performed for 90 days. Comparing the unamended and amended predator results showed that nematode addition beyond bacterial treatment substantially increased the net available P by ≈2 times, and alkaline phosphatase (ALP) activity by 3.3 times. These results demonstrated the nematodes association with increasing nutrient availability or P mineralization. The interactive effect of PM as substrate and biological drivers was more noticeable on plant dry biomass (1.6 times) and plant P concentration (3.5times) compared to the similar unamended treatment. It is concluded that the biological drivers significantly enhanced the soil ALP and available P while the substrate and biological drivers enhanced dry biomass and plant P concentration. Bacterivore nematodes enhanced the effect of PSB for P mineralization via microbial loop and could be used for the enhancement of wheat production.

Allium cepa assay based comparative study of selected vegetables and the chromosomal aberrations due to heavy metal accumulation.

Irrigation of industrial effluents may end in the bioaccumulation of various toxic metals and consequent genetic changes in contaminated food crops. To test this hypothesis and extent of genetic modifications, Allium cepa test was performed to food crops viz. tomato (Lycopersicum esculentum) and chili (Capsicum annum) as Allium cepa test is a useful tool to assess genetic variations in plants. Prior to A. cepa test, the plants were exposed to various metal concentrations 125-1000 mg/L in the synthetic wastewater. The extracts of harvested plants were used to grow the root of A. cepa following its standard method. The root tips were fixed, stained and examined under compound microscope (almost 300-400 dividing cells) to check the extent of chromosomal variations during various stages of mitosis. The results revealed various chromosomal abnormalities including laggards, stickiness, vagrant chromosomes, binucleated cells, nuclear lesions, giant cells and c-mitosis at different level of treatment. On the whole, aberrations were increasing with the increasing doses along the positive control. In comparison, chili crop had higher level of aberrations depicting the higher chromosomal changes. Lower mitotic index (MI) with increasing level of doses was also describing the hampered cell division due to increased metal stress. The study is showing that the cell division was ceased with increasing metal stress thus increasing the rate of cell aberrations.

Identification and inoculation of fungal strains from Cedrus deodara rhizosphere involve in growth and alleviation of high nitrogen stress.

Cedrus deodara is economically and ethnobotanically an important forest tree and is shown to be at decline in Northern areas of Pakistan in recent years mainly due to high concentration of Nitrogen in forests. Ectomycorrhizal (ECM) association forming fungi enables the forest trees to develop optimally by absorbing water from the rhizosphere through their absorptive hyphae and by making available the nutrients by mobilization of N and P from the organic substrates. This study was conducted to identify the ECM strains from C. deodara rhizosphere and to analyse the impact of high N load on the C. deodara seedlings to establish N critical load value for coniferous forests of Pakistan. Six new fungal strains were identified from the rhizosphere of C. deodara and were registered at GenBank (NCBI) as Emmia latemarginata strain ACE1, Aspergillus terreus strain ACE2, Purpureocillium lilacinum strain ACE3, Talaromyces pinophilus strain ACE4, A. fumigatus strain ACE5 and T. pinophilus strain ACE6 with accession numbers MH145426, MH145427, MH145428, MH145429, MH145430 and MH547115. Four out of six isolated strains were inoculated with seedlings of C. deodara singly and in consortium (CN) in combination with nitrogen load of 0 (C), 25 (T1), 50 (T2), 100 kg N ha-1 yr-1 (T3). Agronomic, physiological and gene expression studies for ExpansinA4 (EXPA4) and Cystatins (Cys) were made to analyse the impact of fungal strains in relation to high N stress. This study suggests a positive impact of T1 (25 kg N ha-1 yr-1) Nitrogen load and a negative impact of T3 (100 kg N ha-1 yr-1) on growth parameters and expression patterns of EXPA4 and Cys genes. Peroxidase (POX) activity decreased in the order ACE5 > ACE2 > C > ACE3 > ACE1 > CN. However, the results of Superoxide dismutase (SOD) showed decreasing trend in the order ACE5 > C > CN > ACE1 > ACE2 > ACE3. Strain ACE3 was shown to have a positive impact on the seedlings in terms of growth, physiology and expression of genes. Present study suggests that newly identified fungal strains showing positive impact on the growth and physiology of C. deodara could be used for the propagation of this economically important plant in Pakistan after pathogenicity test.

Bacterial Subspecies Variation and Nematode Grazing Change P Dynamics in the Wheat Rhizosphere.

Low phosphorus soils are thought to constitute the majority of soils worldwide and cannot support intensive agriculture without high fertilizer inputs. Rhizobacteria are well-known to modify P dynamics and an increased bacterial diversity normally has a positive impact on various process rates. However, it is not known how variation in bacterial diversity at the subspecies level could influence trophic interactions in the rhizosphere and its consequences on plant P nutrition. We therefore hypothesized that the interactions between closely related P solubilizing bacteria and their grazing nematodes could improve plant P dynamics from an unavailable P source. We isolated four Pseudomonas poae strains and extracted nematodes from a Saskatchewan wheat field soil sample. The potential of all bacterial isolates with and without nematodes for increasing P availability in the wheat rhizosphere was tested in controlled microcosms with Ca3(PO4)2 as sole P source. Liberated P, phosphatase activity, plant P and bacterial abundance based on phnX gene copies were determined. Phosphorus solubilization efficiency of isolates varied between isolates whereas phosphatase enzyme activity was only detected under nematodes grazing and during the first 15 days of the experiment. Nematodes grazing upon individual Pseudomonas poae increased phosphatase enzyme activity, bacterial abundance, but decreased plant P concentration compared to non-grazed system. In contrast, the treatment combining all Pseudomonas poae isolates together with nematodes resulted in significant increases in P availability and plant P concentration. Diverse P-solubilizing efficiency and interaction with nematodes within the same bacterial "species" suggest that P dynamics might be linked to micro variation in soil diversity that would not accurately be picked up using common tools such as 16S rRNA gene sequencing.

Fractionation of phosphorus in soils amended with poultry manure co-composted with sugarcane and cabbage wastes / Fracionamento de fósforo em solos corrigidos com esterco de aves co-compostado com resíduos de cana de açúcar e repolho

Organic waste recycling is a viable option for reducing energy usage, volume of landfills, air and water pollution, greenhouse gas emissions and preserving natural resources for future use. Composting is an easy and natural bio-degradation process that converts organic wastes into available nutrients for plants. We studied the changes in phosphorus (P) fractions in soils amended with poultry manure co-composted with sugarcane and cabbage wastes. The compost was applied to sandy clay and silt loam soils at 10 and 20 t ha-1. Soils were then incubated at room temperature for 8 weeks when mineralization was expected and analyzed for extractable P fractions. The P fractions in the soils varied in the order HCl-P (Ca+Mg-bound) > H2O-P (water soluble) > NaHCO3-P (readily plant-available P) > NaOH-P (Fe+Albound) and the fractions increased significantly as compost application rates increased and decreased as the amount of sugarcane and cabbage wastes in the compost increased. Phosphorus was less concentrated in the compost containing CW than that containing SW and was higher in sandy clay than silty loam soil. The overall results showed that composting reduced the bio-availability of P from poultry litter and would be beneficial for optimizing P fertility in soil and minimizing losses to the environment.

A reciclagem de resíduos orgânicos é uma opção viável para reduzir o uso de energia, o volume de aterros sanitários, a poluição do ar e da água, as emissões de gases de efeito estufa e a preservação dos recursos naturais para uso futuro. A compostagem é um processo fácil e natural de biodegradação que converte resíduos orgânicos em nutrientes disponíveis para plantas. Estudamos as alterações nas frações de fósforo (P) em solos alterados com esterco de aves de capoeira co-compostada com resíduos de cana de açúcar e repolho. O composto foi aplicado em solos arenosos, argilosos e limosos com 10 e 20 t ha-1. Os solos foram então incubados à temperatura ambiente durante 8 semanas quando a mineralização era esperada e analisada para as frações de P extraíveis. As frações de P nos solos variaram na ordem HCl- P (Ca + Mg-bound) > H2O-P (solúvel em água) > NaHCO3-P ( P prontamente disponível para a planta) > NaOH-P (Fe + Al-bound) e as frações aumentaram significativamente à medida que as taxas de aplicação de composto aumentaram e diminuíram à medida que aumentou a quantidade de resíduos de cana de açúcar e de repolho na compostagem. O fósforo estava menos concentrado no composto contendo CW do que o que continha SW e era mais alto em argila arenosa do que o solo limoso. Os resultados globais mostraram que a compostagem reduziu a biodisponibilidade do P vindo do lixo de aves de capoeira e seria benéfica para otimizar a fertilidade do P no solo e minimizar as perdas para o meio ambiente.

From soil to plant, the journey of P through trophic relationships and ectomycorrhizal association.

Phosphorus (P) is essential for plant growth and productivity. It is one of the most limiting macronutrients in soil because it is mainly present as unavailable, bound P whereas plants can only use unbound, inorganic phosphate (Pi), which is found in very low concentrations in soil solution. Some ectomycorrhizal fungi are able to release organic compounds (organic anions or phosphatases) to mobilize unavailable P. Recent studies suggest that bacteria play a major role in the mineralization of nutrients such as P through trophic relationships as they can produce specific phosphatases such as phytases to degrade phytate, the main form of soil organic P. Bacteria are also more effective than other microorganisms or plants at immobilizing free Pi. Therefore, bacterial grazing by grazers, such as nematodes, could release Pi locked in bacterial biomass. Free Pi may be taken up by ectomycorrhizal fungus by specific phosphate transporters and transferred to the plant by mechanisms that have not yet been identified. This mini-review aims to follow the phosphate pathway to understand the ecological and molecular mechanisms responsible for transfer of phosphate from the soil to the plant, to improve plant P nutrition.