Several anthropogenic activities including mining, modern agricultural practices, and industrialization have long-term detrimental effect on our environment. All these factors lead to increase in ...heavy metal concentration in soil, water, and air. Soil contamination with heavy metals cause several environmental problems and imparts toxic effect on plant as well as animals. In response to these adverse conditions, plants evolve complex molecular and physiological mechanisms for better adaptability, tolerance, and survival. Nowadays conventional breeding and transgenic technology are being used for development of metal stress resistant varieties which, however, are time consuming and labor intensive. Interestingly the use of microbes as an alternate technology for improving metal tolerance of plants is gaining momentum recently. The use of these beneficial microorganisms is considered as one of the most promising methods for safe crop-management practices. Interaction of plants with soil microorganisms can play a vital role in acclimatizing plants to metalliferous environments, and can thus be explored to improve microbe-assisted metal tolerance. Plant-associated microbes decrease metal accumulation in plant tissues and also help to reduce metal bioavailability in soil through various mechanisms. Nowadays, a novel phytobacterial strategy, i.e., genetically transformed bacteria has been used to increase remediation of heavy metals and stress tolerance in plants. This review takes into account our current state of knowledge of the harmful effects of heavy metal stress, the signaling responses to metal stress, and the role of plant-associated microbes in metal stress tolerance. The review also highlights the challenges and opportunities in this continued area of research on plant-microbe-metal interaction.
Pearl millet is a widely cultivated grain and forage crop in areas frequented with hot and dry weather, and high temperature. Being cultivated in arid and semi-arid regions, the crop often encounters ...intermittent water stress either at early stages of development or flowering stage or both. However, its asynchronous tillering behavior and fast growth rate helps recovering from drought stress at vegetative stages while there is no such reprieve under terminal stress (flowering through grain filling). At present, the molecular basis of terminal drought tolerance of certain pearl millet genotypes remains elusive. In this study, a comparative transcriptome analysis has been performed at both vegetative and flowering stages of a terminal drought tolerant genotype, PRLT2/89-33, subjected to drought stress. The gene expression profiling analysis showed that PRLT2/89-33 has an inherent ability to sense drought at both developmental stages. Gene Ontology (GO) and MapMan pathway analyses underlined that flavanoid pathway, lignin biosynthesis, phenyl propanoid pathway, pigment biosynthesis, and other secondary metabolite pathways were enriched in control and drought stressed PRLT2/89-33 at flowering stage than at the vegetative stage. To our knowledge, this is the first report of comparative transcriptome analysis under drought stress at two different developmental stages which can facilitate fastidious discovery of drought tolerant genes leading to improved yield in pearl millet and other related crops.
•Amla juice was spray dried into powder.•Effects of inlet temperature and maltodextrin level on amla powder were studied.•Inlet temperature significantly influenced TPC and DPPH activity of ...powder.•DPPH activity and TPC were significantly influenced by maltodextrin concentration.•Amla powder showed excellent WSI.
The effects of inlet temperatures of 125, 150, 175 and 200°C and maltodextrin levels at 3, 5, 7 and 9% on the physicochemical properties, total phenolic content (TPC) and 2,2-diphenyl picryl hydrazile (DPPH) scavenging activity of spray dried amla juice powder were studied. Moisture content and hygroscopicity of powder were significantly affected by inlet temperature and maltodextrin level. However, an increase in the level of maltodextrin did not significantly affect the bulk density and water solubility index (WSI). An increase in drying temperature and maltodextrin concentration decreased the free radical scavenging activity of the powder. Morphological study revealed that at higher inlet temperatures the spray dried powder had small sized particles that were densely packed. Spray dried amla juice powder made with 7% maltodextrin and processed at 175°C inlet temperature had less hygroscopicity, acceptable color and potent free radical scavenging activity.
Being sessile in nature, plants have to withstand various adverse environmental stress conditions including both biotic and abiotic stresses. Comparatively, abiotic stresses such as drought, ...salinity, high temperature, and cold pose major threat to agriculture by negatively impacting plant growth and yield worldwide. Rice is one of the most widely consumed staple cereals across the globe, the production and productivity of which is also severely affected by different abiotic stresses. Therefore, several crop improvement programs are directed toward developing stress tolerant rice cultivars either through marker assisted breeding or transgenic technology. Alternatively, some known rhizospheric competent bacteria are also known to improve plant growth during abiotic stresses. A plant growth promoting rhizobacteria (PGPR),
NBRI-SN13 (SN13) was previously reported by our lab to confer salt stress tolerance to rice seedlings. However, the present study investigates the role of SN13 in ameliorating various abiotic stresses such as salt, drought, desiccation, heat, cold, and freezing on a popular rice cv. Saryu-52 under hydroponic growth conditions. Apart from this, seedlings were also exogenously supplied with abscisic acid (ABA), salicylic acid (SA), jasmonic acid (JA) and ethephon (ET) to study the role of SN13 in phytohormone-induced stress tolerance as well as its role in abiotic and biotic stress cross-talk. All abiotic stresses and phytohormone treatments significantly affected various physiological and biochemical parameters like membrane integrity and osmolyte accumulation. SN13 also positively modulated stress-responsive gene expressions under various abiotic stresses and phytohormone treatments suggesting its multifaceted role in cross-talk among stresses and phytohormones in response to PGPR. To the best of our knowledge, this is the first report on detailed analysis of plant growth promotion and stress alleviation by a PGPR in rice seedlings subjected to various abiotic stresses and phytohormone treatments for 0, 1, 3, 10, and 24 h.
Pearl millet is one of the most important small-grained C
Panicoid crops with a large genome size (∼2352 Mb), short life cycle and outbreeding nature. It is highly resilient to areas with scanty rain ...and high temperature. Pearl millet is a nutritionally superior staple crop for people inhabiting hot, drought-prone arid and semi-arid regions of South Asia and Africa where it is widely grown and used for food, hay, silage, bird feed, building material, and fuel. Having excellent nutrient composition and exceptional buffering capacity against variable climatic conditions and pathogen attack makes pearl millet a wonderful model crop for stress tolerance studies. Pearl millet germplasm show a large range of genotypic and phenotypic variations including tolerance to abiotic and biotic stresses. Conventional breeding for enhancing abiotic and biotic stress resistance in pearl millet have met with considerable success, however, in last few years various novel approaches including functional genomics and molecular breeding have been attempted in this crop for augmenting yield under adverse environmental conditions, and there is still a lot of scope for further improvement using genomic tools. Discovery and use of various DNA-based markers such as EST-SSRs, DArT, CISP, and SSCP-SNP in pearl millet not only help in determining population structure and genetic diversity but also prove to be important for developing strategies for crop improvement at a faster rate and greater precision. Molecular marker-based genetic linkage maps and identification of genomic regions determining yield under abiotic stresses particularly terminal drought have paved way for marker-assisted selection and breeding of pearl millet cultivars. Reference collections and marker-assisted backcrossing have also been used to improve biotic stress resistance in pearl millet specifically to downy mildew. Whole genome sequencing of pearl millet genome will give new insights for processing of functional genes and assist in crop improvement programs through molecular breeding approaches. This review thus summarizes the exploration of pearl millet genetic and genomic resources for improving abiotic and biotic stress resistance and development of cultivars superior in stress tolerance.
The spoilage enzymes in tender coconut water were inactivated by atmospheric cold plasma technology. The kinetics of peroxidase (POD) and polyphenol oxidase (PPO) inactivation was studied at voltage ...levels varying between 18 and 28 kV dielectric barrier discharge plasma treatments (DBD) at atmospheric air. The time of treatment and applied voltage were significant factors for inactivation of the enzymes. POD was more resistant than PPO. The experimentally observed data were fitted to establish different kinetics models and model parameters were evaluated. The sigmoidal logistic was the best fitting model to explain the kinetics of browning enzymes inactivation based on high RMSE values. The time required for half maximal activity values for POD was 0.84, 1.67 and 2.53 min at 18 kV, 23 kV and 28 kV, respectively which was higher than PPO with half maximal activity values of 0.67, 1.18 and 1.35 min, respectively. This indicates that POD is more resistant to cold plasma than PPO and its inactivation in tender coconut water by cold plasma can be considered as a crucial quality parameter. DBD generated cold plasma can therefore be used to process fruits and vegetables juices wherein enzymes activity is one of the quality deterioration parameters.
•DBD cold plasma used to inactivate POD and PPO in tender coconut water.•Treatment time and applied voltage showed significant inactivation.•POD was more resistant than PPO to DBD cold plasma.•Sigmoidal shaped Logistic model adequately described the enzymes inhibition.•DBD cold plasma can be used as a quality indicator for enzymatically spoiled foods.
Two pigmented and two non-pigmented aromatic rice varieties were analysed for physical dimensions, physicochemical properties, colour, viscosity changes while cooking, phytochemicals content and ...antioxidant capacities. The rices were also evaluated for the effect of cooking on phytochemicals content and antioxidant capacities. While Bakul joha (BJ) and Keteki joha (KJ) varieties are non-pigmented, Poreiton chakhao (PC) is purple coloured and Chak-hao-amubi (CA) is red coloured. The varieties differed in size and shape of the kernels; varying from tiny to big in size, short to long in length, and round to bold in shape. KJ contained the highest amount of protein (9.9%) and PC had the maximum amount of fat (2.1%). Non pigmented rices were of high amylose and of high pasting profile parameters and the pigmented ones were of vice-versa nature. Highest levels of total phenolics, total flavonoid content and ferric reducing antioxidant property (FRAP) were observed in CA (579.00mg GAE 100−1g, 220.5mg QE 100−1g and 5.45mM 100−1g respectively); PC recorded maximum levels of anthocyanin content (35.87mg cyanidin-3-glucoside equivalent 100−1g). Both PC and CA possessed good DPPH (2, 2-diphenyl-1-picrylhydrazyl) radical scavenging activity with 94.19% and 96.43% abilities, respectively. Cooking drastically reduced the phytochemicals and antioxidant capacities. These properties further decreased with keeping time of the cooked rices; PC, however, retained maximum amounts compared to others. The study revealed wide differences in the properties of the aromatic rices. PC (purple) was superior to CA (red) for cumulative phytochemicals content and antioxidant properties.
► Pigmented waxy varieties showed very low viscosity on heating, cooking and cooling. ► The pigmented rices had high phytochemicals content and antioxidant capacities. ► Cooking caused drastic reduction in phytochemicals level and antioxidant capacities. ► Pigmented Poreiton chakhao (purple colour) had high levels of anthocyanins. ► Purple rice was superior in phytochemicals content and antioxidant properties.
Crop growth and productivity has largely been vulnerable to various abiotic and biotic stresses that are only set to be compounded due to global climate change. Therefore developing improved ...varieties and designing newer approaches for crop improvement against stress tolerance have become a priority now-a-days. However, most of the crop improvement strategies are directed toward staple cereals such as rice, wheat, maize etc., whereas attention on minor cereals such as finger millet
(L.) Gaertn. lags far behind. It is an important staple in several semi-arid and tropical regions of the world with excellent nutraceutical properties as well as ensuring food security in these areas even during harsh environment. This review highlights the importance of finger millet as a model nutraceutical crop. Progress and prospects in genetic manipulation for the development of abiotic and biotic stress tolerant varieties is also discussed. Although limited studies have been conducted for genetic improvement of finger millets, its nutritional significance in providing minerals, calories and protein makes it an ideal model for nutrition-agriculture research. Therefore, improved genetic manipulation of finger millets for resistance to both abiotic and biotic stresses, as well as for enhancing nutrient content will be very effective in millet improvement.
Apart from the excellent nutraceutical value of finger millet, its ability to tolerate various abiotic stresses and resist pathogens make it an excellent model for exploring vast genetic and genomic potential of this crop, which provide us a wide choice for developing strategies for making climate resilient staple crops.
The APETALA2/ethylene-responsive element binding factor (AP2/ERF) family is one of the largest transcription factor (TF) families in plants that includes four major sub-families, namely AP2, DREB ...(dehydration responsive element binding), ERF (ethylene responsive factors) and RAV (Related to ABI3/VP). AP2/ERFs are known to play significant roles in various plant processes including growth and development and biotic and abiotic stress responses. Considering this, a comprehensive genome-wide study was conducted in foxtail millet (Setaria italica L.). A total of 171 AP2/ERF genes were identified by systematic sequence analysis and were physically mapped onto nine chromosomes. Phylogenetic analysis grouped AP2/ERF genes into six classes (I to VI). Duplication analysis revealed that 12 (∼7%) SiAP2/ERF genes were tandem repeated and 22 (∼13%) were segmentally duplicated. Comparative physical mapping between foxtail millet AP2/ERF genes and its orthologs of sorghum (18 genes), maize (14 genes), rice (9 genes) and Brachypodium (6 genes) showed the evolutionary insights of AP2/ERF gene family and also the decrease in orthology with increase in phylogenetic distance. The evolutionary significance in terms of gene-duplication and divergence was analyzed by estimating synonymous and non-synonymous substitution rates. Expression profiling of candidate AP2/ERF genes against drought, salt and phytohormones revealed insights into their precise and/or overlapping expression patterns which could be responsible for their functional divergence in foxtail millet. The study showed that the genes SiAP2/ERF-069, SiAP2/ERF-103 and SiAP2/ERF-120 may be considered as potential candidate genes for further functional validation as well for utilization in crop improvement programs for stress resistance since these genes were up-regulated under drought and salinity stresses in ABA dependent manner. Altogether the present study provides new insights into evolution, divergence and systematic functional analysis of AP2/ERF gene family at genome level in foxtail millet which may be utilized for improving stress adaptation and tolerance in millets, cereals and bioenergy grasses.
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