Drought and heat stress mediated activation of lipid signaling in plants: a critical review

Lipids are a principal component of plasma membrane, acting as a protective barrier between the cell and its surroundings. Abiotic stresses such as drought and temperature induce various lipid-dependent signaling responses, and the membrane lipids respond differently to environmental challenges. Recent studies have revealed that lipids serve as signal mediators forreducing stress responses in plant cells and activating defense systems. Signaling lipids, such as phosphatidic acid, phosphoinositides, sphingolipids, lysophospholipids, oxylipins, and N-acylethanolamines, are generated in response to stress. Membrane lipids are essential for maintaining the lamellar stack of chloroplasts and stabilizing chloroplast membranes under stress. However, the effects of lipid signaling targets in plants are not fully understood. This review focuses on the synthesis of various signaling lipids and their roles in abiotic stress tolerance responses, providing an essential perspective for further investigation into the interactions between plant lipids and abiotic stress

Bio-techniques for improvement of qualitative and quantitative traits in walnut (Juglans regia)

Walnut, Juglans regia (L.) is an economically significant plant for its immense nutritive and economic value. The breeding character of walnut has lent it a wide diversity in genetic characteristics. The principal vegetative and common traditional agronomic traits together with biochemical characterization i.e., karyotyping and isoenzyme expression have been the early research methods. However, these techniques are time-consuming and susceptible to the environmental variations. Literature is meager in the distribution, applied applications in general and the use of agriculture biotechnology in particular in case of walnut plants. The bio-techniques like molecular markers are adequate in number and there is little or no diversity in the method employed for research on walnuts. Despite basic research method, the organization of information, its retrieval and presentation structures, form elaboration experienced immense advancement via molecular markers such as RFLP, ISSR, RAPD AFLP, SSR and SNP. This appraisal in its first part provides detailed information regarding the present scenario of data on biogeographical distribution, health benefits of walnut worldwide and current applications in the agroforestry management, biochemical evaluations and applied uses of a walnut tree which is relevant for both basic and applied research. The review in its second part sheds light on the application of sophisticated agricultural biotechnology techniques such as use of molecular markers to evaluate, realize the full potential of walnut for increasing its quality, quantity and for its sustainable production which cannot be obtained through usual breeding techniques to meet the demands of a projected world population

Chemical priming enhances plant tolerance to salt stress

Salt stress severely limits the productivity of crop plants worldwide and its detrimental effects are aggravated by climate change. Due to a significant world population growth, agriculture has expanded to marginal and salinized regions, which usually render low crop yield. In this context, finding methods and strategies to improve plant tolerance against salt stress is of utmost importance to fulfill food security challenges under the scenario of the ever-increasing human population. Plant priming, at different stages of plant development, such as seed or seedling, has gained significant attention for its marked implication in crop salt-stress management. It is a promising field relying on the applications of specific chemical agents which could effectively improve plant salt-stress tolerance. Currently, a variety of chemicals, both inorganic and organic, which can efficiently promote plant growth and crop yield are available in the market. This review summarizes our current knowledge of the promising roles of diverse molecules/compounds, such as hydrogen sulfide (H2S), molecular hydrogen, nitric oxide (NO), hydrogen peroxide (H2O2), melatonin, chitosan, silicon, ascorbic acid (AsA), tocopherols, and trehalose (Tre) as potential primers that enhance the salinity tolerance of crop plants

Harnessing Genome Editing Techniques to Engineer Disease Resistance in Plants

Modern genome editing (GE) techniques, which include clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated protein 9 (CRISPR/Cas9) system, transcription activator-like effector nucleases (TALENs), zinc-finger nucleases (ZFNs) and LAGLIDADG homing endonucleases (meganucleases), have so far been used for engineering disease resistance in crops. The use of GE technologies has grown very rapidly in recent years with numerous examples of targeted mutagenesis in crop plants, including gene knockouts, knockdowns, modifications, and the repression and activation of target genes. CRISPR/Cas9 supersedes all other GE techniques including TALENs and ZFNs for editing genes owing to its unprecedented efficiency, relative simplicity and low risk of off-target effects. Broad-spectrum disease resistance has been engineered in crops by GE of either specific host-susceptibility genes (S gene approach), or cleaving DNA of phytopathogens (bacteria, virus or fungi) to inhibit their proliferation. This review focuses on different GE techniques that can potentially be used to boost molecular immunity and resistance against different phytopathogens in crops, ultimately leading to the development of promising disease-resistant crop varieties

Influences of Priming on Selected Physiological Attributes and Protein Pattern Responses of Salinized Wheat with Extracts of Hormophysa cuneiformis and Actinotrichia fragilis

Biological effects of extracts obtained from the seaweeds Hormophysa cuneiformis (J.F.Gmelin) P.C.Silva and Actinotrichia fragilis (Forsskål) Bùrgesen were investigated using wheat for the improvement of growth and amelioration of the negative effects of soil salinity. Exposure of plants to salt stress resulted in an overall decrease in growth, chlorophyll a and b, carotenoids and soluble sugars, as well as nutrient uptake (i.e., K, Ca and Mg) and K+/Na+ ratio. At the same time, increases were found in proline, total free amino acids, phenolic compounds, malondialdehyde (MDA), Na+ ions, as well as the activities of peroxidase (POD), catalase (CAT), and superoxide dismutase (SOD). Priming wheat seeds with H. cuneiformis and A. fragilis extracts mitigated the negative impacts of salinity by enhancing growth and all the above attributes except MDA and Na+. Treatments with H. cuneiformis or A. fragilis extracts resulted in an increased intensity of the polypeptide bands with 200, 159, 120, 40, and 22 KDa which were already apparent in the control. A. fragilis showed higher effectiveness than H. cuneiformis extracts under both control and stressed regimes. Our results highlight “biofertilizer” properties of two seaweeds and furnish mechanistic insight into their salinity-improvement action, which is pertinent for both applied and basic research

Drought and heat stress mediated activation of lipid signaling in plants: a critical review

Lipids are a principal component of plasma membrane, acting as a protective barrier between the cell and its surroundings. Abiotic stresses such as drought and temperature induce various lipid-dependent signaling responses, and the membrane lipids respond differently to environmental challenges. Recent studies have revealed that lipids serve as signal mediators forreducing stress responses in plant cells and activating defense systems. Signaling lipids, such as phosphatidic acid, phosphoinositides, sphingolipids, lysophospholipids, oxylipins, and N-acylethanolamines, are generated in response to stress. Membrane lipids are essential for maintaining the lamellar stack of chloroplasts and stabilizing chloroplast membranes under stress. However, the effects of lipid signaling targets in plants are not fully understood. This review focuses on the synthesis of various signaling lipids and their roles in abiotic stress tolerance responses, providing an essential perspective for further investigation into the interactions between plant lipids and abiotic stress

The Impact of Priming with Al2O3 Nanoparticles on Growth, Pigments, Osmolytes, and Antioxidant Enzymes of Egyptian Roselle (Hibiscus sabdariffa L.) Cultivar

Lower concentrations of nanoparticles (NPs) could have positive effects on plants. In the present experiment, we tested the efficacy of seed priming Egyptian roselle cultivar with aluminum oxide nanoparticles (Al2O3 NPs). Plants grown with different concentrations (0.01, 0.05, 0.1, and 0.5%) of Al2O3 NPs-primed seeds showed varied responses. An increasing impact with 0.01% Al2O3 NPs was noticed on growth traits, such as fresh weight, dry weight, shoot length, root length, and leaf area, and physio-biochemical activities like chlorophyll a, chlorophyll b, carotenoid contents, soluble sugars, protein, amino acid, proline, and the activities of defense enzymes viz-superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and ascorbate peroxidase (APX). Nevertheless, a decrease was noted in malondialdehyde (MDA) when plants were primed with 0.01% Al2O3 NPs. Seed priming with 0.05, 0.1, and 0.5% Al2O3 NPs caused the negative effects in the aforementioned parameters. The principal component analysis revealed significant correlations among the various studied parameters. Therefore, seed priming with Al2O3 NPs at 0.01% was expected to serve as an effective measure for inducing positive effect in Egyptian roselle cultivar

Putrescine Mitigates High Temperature Effects by Modulating Morpho-Physiological and Biochemical Attributes in Brassica juncea Seedlings

A variety of environmental issues are affecting crops all across the world, but rising temperatures are posing the greatest threat. High temperature has been found to drastically inhibit seedling emergence and cause leaf necrosis at the seedling stage, which results in poor plant stand and significantly decreased yields. Polyamines (PAs) are positively charged, low-molecular-weight aliphatic nitrogenous bases present in all living organisms and are involved in various biological processes in plant growth and development, including senescence and response to different abiotic stresses. Putrescine (Put) functions as a master growth regulator that promotes optimal plant development and greater stress tolerance. Here, the current study aimed to elucidate how Put (1 mM) functions in reducing the negative impacts of high temperature on four varieties of Brassica juncea (RH-1707, RH-1708, RH-1566 and RH-1999-42). Exposure of plants to high temperature resulted in decrease in growth parameters, chlorophyll content and relative water content. Simultaneously, increases were found in antioxidant enzymes, electrolyte leakage, lipid peroxidation, hydrogen peroxide content and stomatal density. High temperature more significantly affected varieties RH-1707 and RH-1708, while RH-1566 and RH-1999-42 showed lesser effects. Exogenous application of Put mitigated the negative impacts of high temperature by enhancing growth, chlorophyll content, relative water content and antioxidant enzyme activities and, simultaneously, it reduces oxidative damage and stomatal density. This study specifies that varieties RH-1707 and RH-1708 are sensitive whereas RH-1566 and RH-1999-42 are tolerant of high temperature and provides an insight into the effectiveness of Put in mitigating the effects of high temperature to a significant extent in B. juncea seedlings

Mitigation of Copper Stress in Maize by Inoculation with Paenibacillus polymyxa and Bacillus circulans

Copper (Cu) is a micronutrient that assumes a principal role in plant growth and development. However, its excess concentration in soil is imperiling crop productivity. Inoculation with different bacterial strains in cereals could modify growth traits, photosynthetic effectiveness, and generation of strong antioxidant defense systems to make them more tolerant of Cu stress. Therefore, a pot study was designed to test plant growth-promoting rhizobacteria (PGPR) including Paenibacillus polymyxa and Bacillus circulans to Cu exposed maize (Zea mays L.) plants. Increasing Cu (100 to 500 µM of CuSO4) concentration decreased growth traits, photosynthetic pigments, soluble sugars, phosphorous (P) and potassium (K) contents, and the activity of catalase (CAT) but increased proline and malondialdehyde (MDA) content, the activity of peroxidase (POD) and Cu ions at root and shoot level. Moreover, the bacterial treatment also modulated the antioxidant capability in stress-free plants. Nevertheless, inoculation with P. polymyxa and B. circulans alleviated Cu-induced growth, photosynthetic pigments and mineral nutrient (P and K) on one hand and regulating the pools of osmolytes and antioxidant enzymes, whilst simultaneously reducing MDA and Cu root and shoot contents. These improved activities of antioxidant enzymes and the regulation of osmolytes content elicited by the blend of bacterial inoculation would have retained the ability of maize plants to confer resilience to Cu stress. This study further affirms that the application of two specific bacterial strains to maize plants proved very effective to ameliorate the Cu toxicity

Drought-Induced Morpho-Physiological, Biochemical, Metabolite Responses and Protein Profiling of Chickpea (Cicer arietinum L.)

The chickpea (Cicer arieitnum L.) is an important food legume crop of the family Fabaceae with high protein levels that is widely grown in rainfed areas prone to drought stress. It is a self-pollinated cool season crop with a true diploid (2n = 16) nature. It is relatively cheap and a high source of protein. About 90% of the chickpea crop is grown by the use of residual moisture in the soil without depending on irrigation. In the present study, two varieties of chickpea, namely ICC 4958 and HC-6, were grown under three field capacities (FC) (100% FC, 50% FC and 25% FC). Samples were taken three times, i.e., 15, 30 and 45 days after sowing (DAS). Parameters such as morphological, physiological, biochemical, metabolite and protein profiling of the two varieties were completed. Morphological parameters such as shoot length (14.2%), number of branches (20.7%), number of leaves (17.5%) and yield (56%) declined as the drought level increased and other characteristics such as root length (9.7%), number of flowers (24.5%) and number of pods (34.4%) increased as drought stress progressed. Physiological parameters such as relative water content (RWC) (13.5%), cell membrane stability (CMS) (29.6%) and chlorophyll content decreased, whereas electrolyte conductivity (EC) (38%) increased in both the varieties as field capacity decreased. Biochemical parameters such as proline (54.75%), sugar (15.2%), glycine betaine (32.25%), superoxide dismutase (SOD) (49.5%), catalase (CAT) (50.5%), ascorbate peroxidase (APX) (44.9%) and glutathione reductase (GR) (49%) increased as drought stress increased. Metabolite analyses of, for example, MDA (malondialdehyde) content (30.5%), total anthocyanin (36.3%), flavonoid content (26%) and phenolic content (29.5%) increased as drought progressed. We also performed protein profiling of the two varieties using SDS-PAGE (sodium dodecyl-sulfate polyacrylamide gel electrophoresis) to differentiate the expression analysis of the two varieties