Morpho-physiological responses and growth indices of triticale to drought and salt stresses

Response of Elymus nutans Griseb. seedling physiology and endogenous hormones to drought and salt stress

Elymus nutans Griseb. (E. nutans), a pioneer plant for the restoration of high quality pasture and vegetation, is widely used to establish artificial grasslands and ecologically restore arid and salinized soils. To investigate the effects of drought stress and salt stress on the physiology and endogenous hormones of E. nutans seedlings, this experiment configured the same environmental water potential (0 (CK), - 0.04, - 0.14, - 0.29, - 0.49, - 0.73, and - 1.02 MPa) of PEG-6000 and NaCl stress to investigate the effects of drought stress and salt stress, respectively, on E. nutans seedlings under the same environmental water potential. The results showed that although the physiological indices and endogenous hormones of the E. nutans seedlings responded differently to drought stress and salt stress under the same environmental water potential, the physiological indices of E. nutans shoots and roots were comprehensively evaluated using the genus function method, and the physiological indices of the E. nutans seedlings under the same environmental water potential exhibited better salt tolerance than drought tolerance. The changes in endogenous hormones of the E. nutans seedlings under drought stress were analyzed to find that treatment with gibberellic acid (GA3), gibberellin A7 (GA7), 6-benzyladenine (6-BA), 6-(y,y-dimethylallylaminopurine) (2.IP), trans-zeatin (TZ), kinetin (KT), dihydrozeatin (DHZ), indole acetic acid (IAA), and 2,6-dichloroisonicotininc acid (INA) was more effective than those under drought stress. By analyzing the amplitude of changes in the endogenous hormones in E. nutans seedlings, the amplitude of changes in the contents of GA3, GA7, 6-BA, 2.IP, TZ, KT, DHZ, IAA, isopentenyl adenosine (IPA), indole-3-butyric acid (IBA), naphthalene acetic acid (NAA), and abscisic acid was larger in drought stress compared with salt stress, which could be because the endogenous hormones are important for the drought tolerance of E. nutans itself. The amplitude of the changes in the contents of DHZ, TZR, salicylic acid, and jasmonic acid was larger in salt stress compared with drought stress. Changes in the content of melatonin were larger in salt stress compared with drought stress, which could indicate that endogenous hormones and substances are important for the salt tolerance of E. nutans itself.

Defense Pathways of Wheat Plants Inoculated with Zymoseptoria tritici under NaCl Stress Conditions: An Overview

Due to being sessile, plants develop a broad range of defense pathways when they face abiotic or biotic stress factors. Although plants are subjected to more than one type of stress at a time in nature, the combined effects of either multiple stresses of one kind (abiotic or biotic) or more kinds (abiotic and biotic) have now been realized in agricultural lands due to increases in global warming and environmental pollution, along with population increases. Soil-borne pathogens, or pathogens infecting aerial parts, can have devastating effects on plants when combined with other stressors. Obtaining yields or crops from sensitive or moderately resistant plants could be impossible, and it could be very difficult from resistant plants. The mechanisms of combined stress in many plants have previously been studied and elucidated. Recent studies proposed new defense pathways and mechanisms through signaling cascades. In light of these mechanisms, it is now time to develop appropriate strategies for crop protection under multiple stress conditions. This may involve using disease-resistant or stress-tolerant plant varieties, implementing proper irrigation and drainage practices, and improving soil quality. However, generation of both stress-tolerant and disease-resistant crop plants is of crucial importance. The establishment of a database and understanding of the defense mechanisms under combined stress conditions would be meaningful for the development of resistant and tolerant plants. It is clear that leaf pathogens show great tolerance to salinity stress and result in pathogenicity in crop plants. We noticed that regulation of the stomata through biochemical applications and some effort with the upregulation of the minor gene expressions indirectly involved with the defense mechanisms could be a great way to increase the defense metabolites without interfering with quality parameters. In this review, we selected wheat as a model plant and Zymoseptoria tritici as a model leaf pathogen to evaluate the defense mechanisms under saline conditions through physiological, biochemical, and molecular pathways and suggested various ways to generate tolerant and resistant cereal plants.

Upregulation of TaHSP90A transcripts enhances heat tolerance and increases grain yield in wheat under changing climate conditions

Plants have certain adaptation mechanisms to combat temperature extremes and fluctuations. The heat shock protein (HSP90A) plays a crucial role in plant defence mechanisms under heat stress. In silico analysis of the eight TaHSP90A transcripts showed diverse structural patterns in terms of intron/exons, domains, motifs and cis elements in the promoter region in wheat. These regions contained cis elements related to hormones, biotic and abiotic stress and development. To validate these findings, two contrasting wheat genotypes E-01 (thermo-tolerant) and SHP-52 (thermo-sensitive) were used to evaluate the expression pattern of three transcripts TraesCS2A02G033700.1, TraesCS5B02G258900.3 and TraesCS5D02G268000.2 in five different tissues at five different temperature regimes. Expression of TraesCS2A02G033700.1 was upregulated (2-fold) in flag leaf tissue after 1 and 4h of heat treatment in E-01. In contrast, SHP-52 showed downregulated expression after 1h of heat treatment. Additionally, it was shown that under heat stress, the increased expression of TaHSP90A led to an increase in grain production. As the molecular mechanism of genes involved in heat tolerance at the reproductive stage is mostly unknown, these results provide new insights into the role of TaHSP90A transcripts in developing phenotypic plasticity in wheat to develop heat-tolerant cultivars under the current changing climate scenario.

Unraveling the plethora of toxicological implications of nanoparticles on living organisms and recent insights into different remediation strategies: A comprehensive review

Increased use of nanoscale particles have benefited many industries, including medicine, electronics, and environmental cleaning. These particles provide higher material performance, greater reactivity, and improved drug delivery. However, the main concern is the generation of nanowastes that can spread in different environmental matrices, posing threat to our environment and human health. Nanoparticles (NPs) have the potential to enter the food chain through a variety of pathways, including agriculture, food processing, packaging, and environmental contamination. These particles can negatively impact plant and animal physiology and growth. Due to the assessment of their environmental damage, nanoparticles are the particles of size between 1 and 100 nm that is the recent topic to be discussed. Nanoparticles' absorption, distribution, and toxicity to plants and animals can all be significantly influenced by their size, shape, and surface chemistry. Due to their absorptive capacity and potential to combine with other harmful substances, they can alter the metabolic pathways of living organisms. Nevertheless, despite the continuous research and availability of data, there are still knowledge gaps related to the ecotoxicology, prevalence and workable ways to address the impact of nanoparticles. This review focuses on the impact of nanoparticles on different organisms and the application of advanced techniques to remediate ecosystems using hyperaccumulator plant species. Future considerations are explored around nano-phytoremediation, as an eco-friendly, convenient and cost effective technology that can be applied at field scales.

Response of nine triticale genotypes to different salt concentrations at the germination and early seedling stages

Salinity stress poses a major challenge to agricultural productivity worldwide, and understanding their responses at the early growth stage is vital for devising strategies to cope with this stress. Therefore, to improve triticale productivity, this study investigated the salinity stress tolerance of different salt-tolerant triticale genotypes aiming to cultivate them on saline soils. To this end, salinity stress impacts on nine triticale genotypes, i.e., Zhongsi 1084, Gannong No. 2, Gannong No. 4, Shida No. 1, C6, C16, C23, C25 and C36 at germination and early seedling stages was evaluated. Each genotype was subjected to six treatments inducing control, 40, 80, 120, 160, and 200 mM NaCl treatments to study their effect on seedling and termination traits of the nine genotypes. Compared to the overall mean seedling vigor index, the seedling vigor index was higher in the genotypes Zhongsi 1084 and C6 (39% and 18.1%, respectively) and lower in Gannong No.2 (41%). Increasing NaCl concentrations negatively affected germination and seedling traits. Compared to other genotypes, Zhongsi 1084 had the highest mean germination rate, germination vigor index, germination percentage, mean daily germination and germination energy. It also showed the lowest relative salt injury. The relative salt injury was higher in the genotype Shida No. 1 than those in Gannong No. 2, Gannong No. 4, Shida No. 1, C16, and C36 genotypes. All genotypes exhibited desirable mean germination time except for line C6. High significant positive correlations were observed among germination rate, germination vigor index, germination percentage, mean daily germination, seedling vigor index, and root length. Principal component analysis (PCA) grouped the most desirable genotypes into two clusters. Our study determined salt stress tolerance of nine triticale genotypes at germination and early seedling stages. to select salt-tolerant genotypes that can be cultivated on saline soil or after salt irrigation.

Effects of exogenous plant regulators on growth and development of "Kyoho" grape under salt alkali stress

Salinity is one of the major abiotic stresses besides drought and cold stress. The application of plant growth regulators (PGRs) is an effective method to mitigate yield losses caused by salinity. However, we investigated the effects of exogenous regulatory substances (γ-aminobutyric acid (GABA), salicylic acid (SA), and brassinolide (BR) on the growth and development of "Kyoho" grapevine under salt stress. The results showed that exogenous regulators GABA, SA, and BR alleviated the inhibition of grape growth by saline stress and regulated the effects of salinity stress on grape fruit development and quality. All three regulators significantly increased fruit set, cross-sectional diameter, weight per unit, and anthocyanin content. In conclusion, this study provides a theoretical basis for grape production practices by using exogenous aminobutyric acid (GABA), salicylic acid (SA), and brassinolide (BR) to mitigate the hazards of salinity stress.

Plant beneficial microbiome a boon for improving multiple stress tolerance in plants

Beneficial microbes or their products have been key drivers for improving adaptive and growth features in plants under biotic and abiotic stress conditions. However, the majority of these studies so far have been utilized against individual stressors. In comparison to individual stressors, the combination of many environmental stresses that plants experience has a greater detrimental effect on them and poses a threat to their existence. Therefore, there is a need to explore the beneficial microbiota against combined stressors or multiple stressors, as this will offer new possibilities for improving plant growth and multiple adaptive traits. However, recognition of the multifaceted core beneficial microbiota from plant microbiome under stress combinations will require a thorough understanding of the functional and mechanistic facets of plant microbiome interactions under different environmental conditions in addition to agronomic management practices. Also, the development of tailored beneficial multiple stress tolerant microbiota in sustainable agriculture necessitates new model systems and prioritizes agricultural microbiome research. In this review, we provided an update on the effect of combined stressors on plants and their microbiome structure. Next, we discussed the role of beneficial microbes in plant growth promotion and stress adaptation. We also discussed how plant-beneficial microbes can be utilized for mitigating multiple stresses in plants. Finally, we have highlighted some key points that warrant future investigation for exploring plant microbiome interactions under multiple stressors.

Morpho-physiological and biochemical characterization of African spider plant (Gynandropsis gynandra (L.) Briq.) genotypes under drought and non-drought conditions

The African spider plant (Gynandropsis gynandra (L.) Briq.) is a nutrient-dense, climate-resilient indigenous vegetable with a C4 carbon fixation pathway. Understanding African spider plant drought tolerance mechanisms is essential for improving its performance in water-stressed areas. The objective of this study was to evaluate the stress tolerance potential of African spider plant accessions based on thirteen morphological, physiological, and biochemical traits under three different water treatment regimes. Eighteen accessions were evaluated over two growing seasons in the greenhouse using a split-split plot design with four replications and three water treatment-regimes namely optimum (100% field capacity), intermediate drought (50% field capacity) and, severe drought (30% field capacity). The results revealed that water regime had a significant effect (P< 0.01) on the accessions for the traits studied. A significant reduction across most of the studied traits was observed under drought conditions. However, proline content in all the accessions significantly rose under drought conditions. The principal component analysis revealed a considerable difference in the performance of the 18 African spider plant accessions under optimum and drought stress conditions. Several morphological and physiological parameters, including days to 50% flowering (r = 0.80), leaf length (r = 0.72), net photosynthesis (r = 0.76) and number of leaves per plant (r = 0.79), were positively associated with leaf yield under drought conditions. Cluster analysis categorized the 18 accessions and 13 measured parameters into 4 clusters, with cluster-1 exhibiting greater drought tolerance for most of the studied traits, and cluster-4 having the most drought-sensitive accessions. Among the accessions tested, accessions L3 and L5 demonstrated excellent drought tolerance and yield performance under both conditions. As a result, these accessions were selected as candidates for African spider plant drought tolerance breeding programs. These findings will serve as the foundation for future studies and will aid in improving food and nutrition security in the face of drought.