In December 2019, the outbreak of viral disease labeled as Novel Coronavirus started in Wuhan, China, which later came to be known as Covid-19. The disease has spread in almost every part of the ...world and has been declared a global pandemic in March 2020 by World Health Organization (WHO). The corona virus outbreak has emerged as one of the deadliest pandemics of all time in human history. The ongoing pandemic of COVID-19 has forced several countries of the world to observe complete lockdown forcing people to live in their homes. India also faced the phase of total lockdown for 21 days (in first phase) to avoid the spread of coronavirus to the maximum possible extent. This lockdown impacted the pollution levels of environment and improved air and water quality in the short span owing to very less human activities. The present work scientifically analyzed the available data for primary air pollutants (PM
2.5
, NO
2
, SO
2
and CO) from two major Indian cities, Lucknow and New Delhi. The analysis was based on air quality data for before lockdown and after lockdown (first phase of 21 days) periods of 21 days each. The results showed significant decline in the studied air pollution indices and demonstrated improvement of air quality in both the cities. The major impact was seen in the levels of PM
2.5
, NO
2
and CO. The levels of SO
2
showed less significant decline during the lockdown period. The results are presented with future perspectives to mitigate air pollution in near future by adopting the short and periodical lockdown as a tool.
Salinity stress is one of the major abiotic stresses threatening sustainable crop production worldwide. The extent of salinity affected area is expected to cover about 50% of total agricultural land ...by 2050. Salinity stress produces various detrimental effects on plants’ physiological, biochemical, and molecular features and reduces productivity. The poor plant growth under salinity stress is due to reduced nutrient mobilization, hormonal imbalance, and formation of reactive oxygen species (ROS), ionic toxicity, and osmotic stress. Additionally, salinity also modulates physicochemical properties and reduces the microbial diversity of soil and thus decreases soil health. On the other hand, the demand for crop production is expected to increase in coming decades owing to the increasing global population. Conventional agricultural practices and improved salt-tolerant crop varieties will not be sufficient to achieve the yields desired in the near future. Plants harbor diverse microbes in their rhizosphere, and these have the potential to cope with the salinity stress. These salinity-tolerant plant growth-promoting bacteria (PGPB) assist the plants in withstanding saline conditions. These plant-associated microbes produce different compounds such as 1-aminocyclopropane-1-carboxylate (ACC) deaminase, indole-3-acetic acid (IAA), antioxidants, extracellular polymeric substance (EPS), and volatile organic compounds (VOC). Additionally, the naturally associated microbiome of plants has the potential to protect the host through stress avoidance, tolerance, and resistance strategies. Recent developments in microbiome research have shown ways in which novel microbe-assisted technologies can enhance plant salt tolerance and enable higher crop production under saline conditions. This focused review article presents the global scenario of salinity stress and discusses research highlights regarding PGPB and the microbiome as a biological tool for mitigation of salinity stress in plants.
•The major source of arsenic exposure in human is rice and rice-based products.•Apart from rice, As levels in other important dietary sources has also been covered.•The level of As species (iAs/oAs) ...influences the associated As toxicity in food.•It is mandatory to set the regulatory limits of arsenic in food at earliest.
Arsenic (As) is a carcinogenic element threatening the health of millions of people around the world. The sources for human exposure include drinking water, crops, processed food items, vegetables, mushrooms, animal products etc. The people at most risk are those living in hotspots of As contamination viz., Bangladesh and West Bengal, India. However, it has been found that rice growing in other uncontaminated regions like Australia can also contain high As levels. Further, rice import/export among various countries make the problem of global concern. The emergence of several reports of As in rice based food products including baby food from different parts of the world demonstrates that even the infants and toddlers are not spared. The variation in the levels of inorganic and organic As species in different food items influence the associated As toxicity. This review tries to present the available data on As levels in various dietary sources.
Arsenic (As) is a non-essential toxic metalloid whose elevated concentration in rice grains is a serious issue both for rice yield and quality, and for human health. The rice-As interactions, hence, ...have been studied extensively in past few decades. A deep understanding of factors influencing As uptake and transport from soil to grains can be helpful to tackle this issue so as to minimize grain As levels. As uptake at the root surface by rice plants depends on factors like iron plaque and radial oxygen loss. There is involvement of a number of transporters
., phosphate transporters and aquaglyceroporins in the uptake and transport of different As species and in the movement to subcellular compartments. These processes are also affected by sulfur availability and consequently on the level of thiol (-SH)-containing As binding peptides viz., glutathione (GSH) and phytochelatins (PCs). Further, the role of phloem in As movement to the grains is also suggested. This review presents a detailed map of journey of As from soil to the grains. The implications for the utilization of available knowledge in minimizing As in rice grains are presented.
The present study measured arsenic (As) concentrations in soil, groundwater and rice grain samples in two villages, Sarapur and Chinili, under Chakdaha block, Nadia district, West Bengal, India. This ...study also included a survey of the two villages to understand the knowledge among villagers about the As problem. Soil and groundwater samples were collected from fields in two villages while rice grain samples were collected from villagers’ houses. The results revealed the presence of As in higher concentrations than the maximum permissible limit of As in drinking water (10 µg L
−1
and 50 µg L
−1
by WHO and Indian standard, respectively) in groundwater 124.50 ± 1.11 µg L
−1
(Sarapur) and 138.20 ± 1.34 µg L
−1
(Chinili). The level of As in soil was found to range from 47.7 ± 0.14 to 49.3 ± 0.19 mg Kg
−1
in Sarapur and from 57.5 ± 0.25 to 62.5 ± 0.44 mg Kg
−1
in Chinili which are also higher than European Union maximum acceptable limit in agricultural soil (i.e. 20 mg Kg
−1
). The analysis of As in rice grains of five varieties, collected from residents of two villages, showed the presence of higher than recommended safe level of As in rice by FAO/WHO (0.2 mg Kg
−1
). The As concentration order was Gosai (0.95 ± 0.044 mg kg
−1
), Satabdi (0.79 ± 0.038 mg kg
−1
), Banskathi (0.60 ± 0.026 mg kg
−1
), Kunti (0.47 ± 0.018 mg kg
−1
) and Ranjit (0.29 ± 0.021 mg kg
−1
). Importantly, Gosai and Satabdi were the most popular varieties being consumed by local people. The data of consumption of rice per day in the survey was used for the measurement of average daily dose and hazard quotient. It was seen that the As hazard was negatively correlated to the age of residents. Therefore, children and toddlers were at higher risk of As exposure than elderly people. In addition, people with skin related As toxicity symptoms were also cited in the two villages. The study emphasized the severity of As problem in remote areas of West Bengal, India where people consume As tainted rice due to lack of awareness about the As problem and associated health issues.
•Microbial consortium of P. putida and C. vulgaris improved the growth and reduced arsenic induced oxidative stress in rice.•The consortium reduced the accumulation of arsenic and also improved the ...level of nutrient elements in rice.•Reduced arsenic in rice due to the consortium alleviated the requirement of thiols and antioxidant enzymes.
In the present study, arsenic (As) toxicity amelioration potential of a consortium of plant growth promoting rhizobacterium (Pseudomonas putida) and alga (Chlorella vulgaris) was evaluated during arsenate (AsV) exposure to rice (Oryza sativa) plants for 15 d. The consortium mediated amelioration of As toxicity was evident through improved growth of rice plants (root and shoot length and biomass) and reduced oxidative stress as level of superoxide radicals (O2−), hydrogen peroxide (H2O2) and membrane damage. The positive responses were attributable to a significant decline in As accumulation in root (94 mg kg−1 dw) and shoot (51 mg kg−1 dw) in consortium (P. putida + C. vulgaris) inoculated seedlings as compared to As alone exposed plants (156 and 98 mg kg−1 dw, respectively). There were also significant changes in the level of various nutrient elements (Mn, Fe, Co, Zn, Mo and Cu), thiols and in the activities of antioxidant and thiol metabolism enzymes in the consortium inoculated seedlings that allowed the plants to tolerate As stress effectively and achieve better growth. The study demonstrated that consortium of P. putida and C. vulgaris may alleviate As stress and improve growth of rice seedlings along with reduction in As levels.
A study was performed for phyto-genotoxic assay of chromium (Cr) and arsenic (As) through
Allium cepa
. Various concentrations (0, 1, 3, 6 and 12 mg L
−1
) of Cr and As for 48 and 168 h time points ...exposed
to A. cepa
. The phytotoxic effects of metal(loid) were evident through inhibited root length and root protein. Metal(loid) toxicity also lead to genotoxic effects, which included depression of mitotic index and increased frequency of chromosomes aberrations like break, fragments, c-metaphase, multipolar arrangements etc. Genotoxic endpoint as progressive frequency of micronuclei in interphase of root meristem cells in treated plants was also observed. This genotoxic endpoint revealed carcinogenic nature of both aforementioned metal(loid). Along with inhibition in root length and protein content, depression in mitotic index as well as stimulation of various abnormality in mitotic cell division indicated that both metal(loid) are hazardous in nature and causing harmful effect on the environment.
The nitrogen (N)-rich ureides allantoin and allantoate, which are products of purine catabolism, play a role in N delivery in Leguminosae. Here, we examined their role as an N source in nonlegume ...plants using Arabidopsis (Arabidopsis thaliana) plants mutated in XANTHINE DEHYDROGENASE1 (AtXDH1), a catalytic bottleneck in purine catabolism. Older leaves of the Atxdh1 mutant exhibited early senescence, lower soluble protein, and lower organic N levels as compared with wild-type older leaves when grown with 1 mm nitrate but were comparable to the wild type under 5 mm nitrate. Similar nitrate-dependent senescence phenotypes were evident in the older leaves of allantoinase (Ataln) and allantoate amidohydrolase (Ataah) mutants, which also are impaired in purine catabolism. Under low-nitrate conditions, xanthine accumulated in older leaves of Atxdh1, whereas allantoin accumulated in both older and younger leaves of Ataln but not in wild-type leaves, indicating the remobilization of xanthine-degraded products from older to younger leaves. Supporting this notion, ureide transporter expression was enhanced in older leaves of the wild type in low-nitrate as compared with high-nitrate conditions. Elevated transcripts and proteins of AtXDH and AtAAH were detected in low-nitrate-grown wild-type plants, indicating regulation at protein and transcript levels. The higher nitrate reductase activity in Atxdh1 leaves compared with wild-type leaves indicated a need for nitrate assimilation products. Together, these results indicate that the absence of remobilized purine-degraded N from older leaves of Atxdh1 caused senescence symptoms, a result of higher chloroplastic protein degradation in older leaves of low-nitrate-grown plants.
Plant growth and development is adversely affected by different kind of stresses. One of the major abiotic stresses, salinity, causes complex changes in plants by influencing the interactions of ...genes. The modulated genetic regulation perturbs metabolic balance, which may alter plant's physiology and eventually causing yield losses. To improve agricultural output, researchers have concentrated on identification, characterization and selection of salt tolerant varieties and genotypes, although, most of these varieties are less adopted for commercial production. Nowadays, phenotyping plants through Machine learning (deep learning) approaches that analyze the images of plant leaves to predict biotic and abiotic damage on plant leaves have increased. Here, we review salinity stress related markers on molecular, physiological and morphological levels for crops such as maize, rice, ryegrass, tomato, salicornia, wheat and model plant,
. The combined analysis of data from stress markers on different levels together with image data are important for understanding the impact of salt stress on plants.
The present study assessed the utility of
Allium cepa
based cyto-genotoxicity bioassays in evaluating the arsenic toxicity and remediation potential of
Pteris vittata
on contaminated soil of ...Lakhimpur-Kheri district. Untreated and
P. vittata
treated soil extracts were used for cyto-genotoxicity tests in
A. cepa
. Results showed that
P. vittata
extracted high concentration of arsenic, which ranged from 220 to 1420 mgkg
−1
in different soils. Cyto-genotoxic assessment of
A. cepa
showed that extract of
P. vittata
treated soil had lower cyto-genotoxic effects as compared to untreated soil. A higher mitotic index (10%) while lower mitotic depression (29%), relative abnormality rate (10%), chromosomal aberrations (1%) and micronuclei (2%) were detected in root meristematic cells of
A. cepa
exposed to remediated soil extract in comparison to untreated soil. The studies provide a simple, rapid and economic cyto-genotoxicity bioassay tool for evaluating toxicity of contaminated soils of contaminated soils as well as revealed the phytoremdiation property of
P. vittata
against arsenic toxicity.
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