Oxidation-reduction process of Arabidopsis thaliana roots induced by bisphenol compounds based on RNA-seq analysis.

Bisphenol compounds (BPs) have various industrial uses and can enter the environment through various sources. To evaluate the ecotoxicity of BPs and identify potential gene candidates involved in the plant toxicity, Arabidopsis thaliana was exposed to bisphenol A (BPA), BPB, BPE, BPF, and BPS at 1, 3, 10 mg/L for a duration of 14 days, and their growth status were monitored. At day 14, roots and leaves were collected for internal BPs exposure concentration detection, RNA-seq (only roots), and morphological observations. As shown in the results, exposure to BPs significantly disturbed root elongation, exhibiting a trend of stimulation at low concentration and inhibition at high concentration. Additionally, BPs exhibited pronounced generation of reactive oxygen species, while none of the pollutants caused significant changes in root morphology. Internal exposure concentration analysis indicated that BPs tended to accumulate in the roots, with BPS exhibiting the highest level of accumulation. The results of RNA-seq indicated that the shared 211 differently expressed genes (DEGs) of these 5 exposure groups were enriched in defense response, generation of precursor metabolites, response to organic substance, response to oxygen-containing, response to hormone, oxidation-reduction process and so on. Regarding unique DEGs in each group, BPS was mainly associated with the redox pathway, BPB primarily influenced seed germination, and BPA, BPE and BPF were primarily involved in metabolic signaling pathways. Our results provide new insights for BPs induced adverse effects on Arabidopsis thaliana and suggest that the ecological risks associated with BPA alternatives cannot be ignored.

Cerium oxide nanoparticles promoted lateral root formation in Arabidopsis by modulating reactive oxygen species and Ca2+ level.

Roots play an important role in plant growth, including providing essential mechanical support, water uptake, and nutrient absorption. Nanomaterials play a positive role in improving plant root development, but there is limited knowledge of how nanomaterials affect lateral root (LR) formation. Poly (acrylic) acid coated nanoceria (cerium oxide nanoparticles, PNC) are commonly used to improve plant stress tolerance due to their ability to scavenge reactive oxygen species (ROS). However, its impact on LR formation remains unclear. In this study, we investigated the effects of PNC on LR formation in Arabidopsis thaliana by monitoring ROS levels and Ca2+ distribution in roots. Our results demonstrate that PNC significantly promote LR formation, increasing LR numbers by 26.2%. Compared to controls, PNC-treated Arabidopsis seedlings exhibited reduced H2 O2 levels by 18.9% in primary roots (PRs) and 40.6% in LRs, as well as decreased O 2 · - levels by 47.7% in PRs and 88.5% in LRs. When compared with control plants, Ca2+ levels were reduced by 35.7% in PRs and 22.7% in LRs of PNC-treated plants. Overall, these results indicate that PNC could enhance LR development by modulating ROS and Ca2+ levels in roots.

Phytochrome-dependent responsiveness to root-derived cytokinins enables coordinated elongation responses to combined light and nitrate cues.

Plants growing at high densities can detect competitors through changes in the composition of light reflected by neighbours. In response to this far-red-enriched light, plants elicit adaptive shade avoidance responses for light capture, but these need to be balanced against other input signals, such as nutrient availability. Here, we investigated how Arabidopsis integrates shade and nitrate signalling. We unveiled that nitrate modulates shade avoidance via a previously unknown shade response pathway that involves root-derived trans-zeatin (tZ) signal and the BEE1 transcription factor as an integrator of light and cytokinin signalling. Under nitrate-sufficient conditions, tZ promotes hypocotyl elongation specifically in the presence of supplemental far-red light. This occurs via PIF transcription factors-dependent inhibition of type-A ARRs cytokinin response inhibitors. Our data thus reveal how plants co-regulate responses to shade cues with root-derived information about nutrient availability, and how they restrict responses to this information to specific light conditions in the shoot.

Antifungal activity of 2-chloro-5-trifluoromethoxybenzeneboronic acid and inhibitory mechanisms on Geotrichum candidum from sour rot Xiaozhou mustard root tuber.

Xiaozhou mustard (Brassica napiformis) root tuber, a traditional fermented vegetable, has a long history in Rongan County, Guangxi Province. However, the frequent occurrence of root tuber sour rot by Geotrichum candidum (G. candidum) has seriously reduced Xiaozhou mustard production and quality in recent years. The objective of the present study is to investigate the antifungal efficacy of 2-chloro-5-trifluoromethoxybenzeneboronic acid (Cl-F-BBA) against G. candidum and its possible mechanisms. The results revealed that a concentration of 0.25 mg/mL Cl-F-BBA completely halted mycelial growth and spore germination. Furthermore, a slightly lower concentration of 0.20 mg/mL was sufficient to compromise the integrity of the plasma membrane in mycelia and mitochondria, leading to a reduction in respiratory rate, activities of malate dehydrogenase (MDH), and succinate dehydrogenase (SDH), ATP content, and energy charge. This concentration also significantly disordered antioxidant metabolism, resulting in the accumulation of reactive oxygen species (ROS) and malondialdehyde (MDA), and caused intracellular leakage in mycelia. In vivo experiments further demonstrated that Xiaozhou mustard root tubers treated with Cl-F-BBA exhibited markedly lower decay rates and lesion diameters compared to the control group. In summary, Cl-F-BBA presents a promising solution for controlling root tuber sour rot in Xiaozhou mustard caused by G. candidum.

Influence of indole acetic acid and trehalose, with and without zinc oxide nanoparticles coated urea on tomato growth in nitrogen deficient soils.

Nitrogen deficiency in low organic matter soils significantly reduces crop yield and plant health. The effects of foliar applications of indole acetic acid (IAA), trehalose (TA), and nanoparticles-coated urea (NPCU) on the growth and physiological attributes of tomatoes in nitrogen-deficient soil are not well documented in the literature. This study aims to explore the influence of IAA, TA, and NPCU on tomato plants in nitrogen-deficient soil. Treatments included control, 2mM IAA, 0.1% TA, and 2mM IAA + 0.1% TA, applied with and without NPCU. Results showed that 2mM IAA + 0.1% TA with NPCU significantly improved shoot length (~ 30%), root length (~ 63%), plant fresh (~ 48%) and dry weight (~ 48%), number of leaves (~ 38%), and leaf area (~ 58%) compared to control (NPCU only). Additionally, significant improvements in chlorophyll content, total protein, and total soluble sugar, along with a decrease in antioxidant activity (POD, SOD, CAT, and APX), validated the effectiveness of 2mM IAA + 0.1% TA with NPCU. The combined application of 2mM IAA + 0.1% TA with NPCU can be recommended as an effective strategy to enhance tomato growth and yield in nitrogen-deficient soils. This approach can be integrated into current agricultural practices to improve crop resilience and productivity, especially in regions with poor soil fertility. To confirm the efficacy of 2mM IAA + 0.1% TA with NPCU in various crops and climatic conditions, additional field studies are required.

Exogenous application of serotonin, with the modulation of redox homeostasis and photosynthetic characteristics, enhances the drought resistance of the saffron plant.

Water stress is one of the most significant abiotic stresses that disrupts the osmotic balance of plants and consequently reduces their growth and performance. In recent years, it has been found that serotonin, as a signaling and regulatory molecule, can play important roles in the growth and development of plants and enhance their tolerance to abiotic stresses. Saffron is a plant known for its medicinal and culinary properties. Its distinct flavor, aroma, and vibrant color make it a sought-after ingredient in various cuisines and traditional medicines. The aim of this study is to investigate the possible effect of serotonin growth regulator on some morphophysiological and biochemical characteristics of saffron plant under water stress conditions. Water stress was applied using polyethylene glycol 6000 at a level of 30%, w/v. Serotonin was also applied exogenously at a concentration of 100 µM in both foliar and root applications. The experimental findings demonstrated that water stress had a detrimental impact on various growth and photosynthetic parameters including FW, DW, SH, RWC, photosynthetic pigments content, Pn, Fv/Fm, C and Ci. Under these conditions, H2O2 content and ion leakage increased. The increase in the content of proline and sugars also confirmed that the saffron plant was placed in unfavorable growth conditions. Serotonin application in both foliar and root applications and especially root treatment under stressful conditions improved plant growth by activating enzymatic and non-enzymatic antioxidant systems. Overall, the exogenous application of serotonin increased the resistance of saffron plants to water stress.

La (NO3)3 substantially fortified Glycyrrhiza uralensis's resilience against salt stress by interconnected pathways.

The taproot of Glycyrrhiza uralensis is globally appreciated for its medicinal and commercial value and is one of the most popular medicinal plants. With the decline of wild G. uralensis resources, cultivated G. uralensis has become a key method to ensure supply. However, soil salinization poses challenges to G. uralensis cultivation and affects the yield and quality of it. In this study, the inhibitory effects of NaCl and Na2SO4 on yield and quality of G. uralensis were comprehensively evaluated in a three-year large-scale pot experiment, and the alleviating effects of supplementation with lanthanum nitrate (La (NO3)3) on G. uralensis were further evaluated under salt stress. The findings indicate that La (NO3)3 significantly strengthened the plant's salt tolerance by enhancing photosynthetic capacity, osmolyte accumulation, antioxidant defenses, and cellular balance of ions, which led to a substantial increase in root biomass and accumulation of major medicinal components. In comparison to the NaCl-stress treatment, the 0.75 M La (NO3)3 + NaCl treatment resulted in a 20% and 34% increase in taproot length and biomass, respectively, alongside a 52% and 43% rise in glycyrrhizic acid and glycyrrhizin content, respectively. Similar improvements were observed with 0.75 M La (NO3)3 + Na2SO4 treatment, which increased root length and biomass by 14% and 26%, respectively, and glycyrrhizic acid and glycyrrhizin content by 40% and 38%, respectively. The combined showed that application of La (NO3)3 not only significantly improved the salt resilience of G. uralensis, but also had a more pronounced alleviation of growth inhibition induced by NaCl compared to Na2SO4 stress except in the gas exchange parameters and root growth. This study provides a scientific basis for high-yield and high-quality cultivation of G. uralensis in saline soils and a new approach for other medicinal plants to improve their salt tolerance.

Novel nanocomposite and biochar insights to boost rice growth and alleviation of Cd toxicity.

Cadmium (Cd) is an unessential and pervasive contaminant in agricultural soil, eventually affecting the food and instigating health issues. The implication of nanocomposites in agriculture attained significant attention to drive food security. Nanocomposites possess exceptional characteristics to stun the challenges of chemical fertilizers that can enhance plant yield and better nutrient bioavailability. Similarly, biochar has the ability to immobilize Cd in soil by reducing mobility and bioavailability. Rice husk biochar is produced at high temperature pyrolysis under anoxic conditions and a stable carbon-rich material is formed. To strive against this issue, rice plants were subjected to Cd (15, 20 mg kg- 1) stress and treated with alone/combined Ca + Mg (25 mg L- 1) nanocomposite and rice husk biochar. In our study, growth and yield traits showed the nurturing influence of Ca + Mg nanocomposite and biochar to improve rice defence mechanism by reducing Cd stress. Growth parameters root length 28%, shoot length 34%, root fresh weight 19%, shoot fresh weight 16%, root dry weight 9%, shoot dry weight 8%, number of tillers 32%, number of grains 20%, and spike length 17% were improved with combined application of Ca + Mg and biochar, with Cd (20 mg kg- 1), rivalled to alone biochar. Combined Ca + Mg and biochar application increased the SPAD 23%, total chlorophyll 26%, a 19%, b 18%, and carotenoids 15%, with Cd (20 mg kg- 1), rivalled to alone biochar. MDA 15%, H2O2 13%, and EL 10% were significantly regulated in shoots with combined Ca + Mg and biochar application with Cd (20 mg kg- 1) compared to alone biochar. POD 22%, SOD 17%, APX 18%, and CAT 9% were increased in shoots with combined Ca + Mg and biochar application with Cd (20 mg kg- 1) compared to alone biochar. Cd uptake in roots 13%, shoots 14%, and grains 21% were minimized under Cd (20 mg kg- 1) with combined Ca + Mg and B. pumilus application, compared to alone biochar. Subsequently, combined Ca + Mg and biochar application is a sustainable solution to boost crop production under Cd stress.

Licorice-root extract and potassium sorbate spray improved the yield and fruit quality and decreased heat stress of the 'osteen' mango cultivar.

Heat stress, low mango yields and inconsistent fruit quality are main challenges for growers. Recently, licorice-root extract (LRE) has been utilized to enhance vegetative growth, yield, and tolerance to abiotic stresses in fruit trees. Potassium sorbate (PS) also plays a significant role in various physiological and biochemical processes that are essential for mango growth, quality and abiotic stress tolerance. This work aimed to elucidate the effects of foliar sprays containing LRE and PS on the growth, yield, fruit quality, total chlorophyll content, and antioxidant enzymes of 'Osteen' mango trees. The mango trees were sprayed with LRE at 0, 2, 4 and 6 g/L and PS 0, 1, 2, and 3 mM. In mid-May, the mango trees were sprayed with a foliar solution, followed by monthly applications until 1 month before harvest. The results showed that trees with the highest concentration (6 g/L) of LRE exhibited the maximum leaf area, followed by those treated with the highest concentration (3 mM) of PS. Application of LRE and PS to Osteen mango trees significantly enhanced fruit weight, number of fruits per tree, yield (kg/tree), yield increasing%, and reduced number of sun-burned fruits compared to the control. LRE and PS foliar sprays to Osteen mango trees significantly enhanced fruit total soluble solids ˚Brix, TSS/acid ratio, and vitamin C content compared to the control. Meanwhile, total acidity percentage in 'Osteen' mango fruits significantly decreased after both LRE and PS foliar sprays. 'Osteen' mango trees showed a significant increase in leaf area, total chlorophyll content, total pigments, and leaf carotenoids. Our results suggest that foliar sprays containing LRE and PS significantly improved growth parameters, yield, fruit quality, antioxidant content, and total pigment concentration in 'Osteen' mango trees. Moreover, the most effective treatments were 3 mM PS and 6 g/L LRE. LRE and PS foliar spray caused a significant increase in yield percentage by 305.77%, and 232.44%, in the first season, and 242.55%, 232.44% in the second season, respectively.

Diethyl aminoethyl hexanoate ameliorates salt tolerance associated with ion transport, osmotic adjustment, and metabolite reprograming in white clover.

BACKGROUND: Soil salinization is a serious environmental hazard, limiting plant growth and production in different agro-ecological zones worldwide. Diethyl aminoethyl hexanoate (DA-6) as an essential plant growth regulator (PGR) exhibits a beneficial role in improving crop growth and stress tolerance. However, the DA-6-regulated effect and mechanism of salt tolerance in plants are still not fully understood. The objective of current study was to disclose salt tolerance induced by DA-6 in relation to changes in water and redox balance, photosynthetic function, ionic homeostasis, and organic metabolites reprogramming in white clover (Trifolium repens). RESULTS: A prolonged duration of salt stress caused water loss, impaired photosynthetic function, and oxidative injury to plants. However, foliar application of DA-6 significantly improved osmotic adjustment (OA), photochemical efficiency, and cell membrane stability under salt stress. In addition, high salinity induced massive accumulation of sodium (Na), but decreased accumulation of potassium (K) in leaves and roots of all plants. DA-6-treated plants demonstrated significantly higher transcript levels of genes involved in uptake and transport of Na and K such as VP1, HKT8, SOS1, NHX2, NHX6, and SKOR in leaves as well as VP1, HKT1, HKT8, H+-ATPase, TPK5, SOS1, NHX2, and SKOR in roots. Metabolomics analysis further illustrated that DA-6 primarily induced the accumulation of glucuronic acid, hexanoic acid, linolenic acid, arachidonic acid, inosose, erythrulose, galactopyranose, talopyranose, urea, 1-monopalmitin, glycerol monostearate, campesterol, stigmasterol, and alanine. CONCLUSIONS: The DA-6 significantly up-regulated transcript levels of multiple genes associated with increased Na+ compartmentalization in vacuoles and Na+ sequestration in roots to reduce Na+ transport to photosynthetic organs, thereby maintaining Na+ homeostasis under salt stress. The accumulation of many organic metabolites induced by the DA-6 could be attributed to enhanced cell wall and membrane structural stability and functionality, OA, antioxidant defense, and downstream signal transduction in leaves under salt stress. The present study provides a deep insight about the synergistic role of DA-6 in salt tolerance of white clover.

Effects of exogenous calcium and calcium inhibitor on physiological characteristics of winter turnip rape (Brassica rapa) under low temperature stress.

Low temperature is one of the environmental factors that restrict the growth and geographical distribution of Brassica. To investigate the effects of exogenous calcium and calcium inhibitor on the ability of winter turnip rapeseed (Brassica rapa L.) to withstand low temperatures (4℃), we used a strong cold-resistant variety Longyou 7 (L7) and a weak cold-resistant variety Longyou 99 (L99) as the materials. The seedlings were treated with CaCl2 (20 mmol·L-1) and calcium inhibitor LaCl3 (10 mmol·L-1) at 0 h (CK), 6 h, 12 h, 24 h and 48 h after 4℃ treatments. Physiological characteristics, Ca2+ flux and Ca2+ concentration in roots after treatments were analyzed. Results illustrated that under 4℃ treatment, activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) increased by both CK and exogenous CaCl2 treatments. Contents of soluble protein (SP) and proline (Pro) increased, while contents of malondialdehyde (MDA) decreased, resulting in reduced membrane lipid peroxidation. But enzyme activity decreased and MDA content increased following treatment with exogenous LaCl3. The rate of Ca2+ flow showed a higher uptake in L7 roots compared with L99. L99 showed Ca2+ efflux with a rate of 30.21 pmol‧cm-2‧s-1, whereas L7 showed short efflux then returned to influx. Calcium ion content in roots decreased in both cultivars after CaCl2 treatment. Results of RNA-seq revealed that genes were differentially expressed in response to low temperatures, hormones, photosystem II, chloroplasts, DNA replication, ribosomal RNA processing, and translation. This study found significant expression genes related to cellular signal transduction (MAPK signaling pathway) and material metabolism (nitrogen metabolism, glycerol ester metabolism).It was also analyzed by WGCNA that two modules had the strongest correlation with physiological indicators. Eight candidate genes were identified among MAPK signaling pathway and the two modules.

Effect of pH on growth and Cd accumulation in different rice varieties under hydroponics.

Currently, applying lime to cadmium (Cd)-contaminated paddy fields to increase pH and reduce Cd availability is an effective method to control excessive Cd levels in rice grain. However, under hydroponic conditions, the impact of increased pH on Cd accumulation in different rice varieties remains unclear. This study employed three rice varieties (Yuzhenxiang, Shaoxiang 100, Xiangwanxian 12) with different Cd accumulation characteristics under different pH and long-term treatment with 1 µM CdCl2, to study the effect of pH on growth and Cd accumulation in different rice varieties. The result showed that as pH shifted from 5 to 8, the SPAD values, shoot dry weight, and plant height of the three rice varieties significantly decreased. The main root length, root volume, and root dry weight of Yuzhenxiang, and Shaoxiang100 significantly decreased. Conversely, the root architecture indicators of Xiangwanxian 12 did not change significantly. As for element accumulation, increasing the pH significantly increased the content of Mn in both the shoots and roots of all three varieties. Yuzhenxiang significantly reduced Cd content in both the shoots and roots of rice, while Shaoxiang100 significantly increased Cd content in both parts. Xiangwanxian 12 showed a significant increase in Cd content in the shoots but a decrease in the roots. In terms of subcellular distribution, Yuzhenxiang significantly reduced Cd concentrations in the cell wall and organelles of root cells, resulting in lower Cd concentrations in the root tissue. Conversely, Shaoxiang100 significantly increased Cd concentrations in the cell wall, organelles, and soluble fractions of root cells, leading to higher Cd concentrations in the root tissue. Xiangwanxian 12 also exhibited a decrease in Cd concentrations in the cell wall, organelles, and soluble fraction of root cells, resulting in lower Cd concentrations in the root tissue. Additionally, the expression of the OsNRAMP5 and OsHMA3 gene was significantly increased in Shaoxiang 100, while no significantly change in Yuzhenxiang and Xiangwanxian 12. These results provide important guidance on the impact of pH on Cd accumulation during the vegetative growth stage of different rice varieties.

Salt stress memory in tall fescue: Interaction of different stress stages, pollination system and genetic diversity.

INTRODUCTION: The effects of salinity memory and its interaction with genetic diversity for drought tolerance and pollination system in terms of morphological, physiological, root characteristics and spectral reflectance indices (SRIs) in tall fescue is still unknown. METHODS: Four tall fescue genotypes (two drought-sensitive and two drought-tolerant) were manually controlled to produce four selfed (S1) and four open-pollinated (OP) progeny genotypes (finally eight progeny genotypes). Then all genotypes were assessed for two years in greenhouse under five salinity treatments including control treatment (C), twice salinity stress treatment (primary mild salinity stress in two different stages and secondary at the end stage) (S1t1S2 and S1t2S2), once severe salinity stress treatment (secondary only, S2), and foliar spray of salicylic acid (SA) simultaneously with secondary salinity stress (H2S2). RESULTS: Results indicated that obligate selfing (S1) caused to inbreeding depression in RWC, plant growth, catalase activity, root length and the ratio of root/shoot (R/S). Once salinity stress treatment (S2) led to depression in most measured traits, while pre-exposure to salinity (salinity memory) (S1t1S2 and S1t2S2) improved photosynthetic pigments, proline, antioxidant enzymes and R/S. CONCLUSION: Salinity memory was more pronounced in drought-sensitive genotypes, while it was more evident in OP than S1 population. Foliar spray of salicylic acid (SA) was almost equally effective in reducing the effects of salinity stress in both populations. The efficacy of application was more pronounced in tolerant genotypes compared to sensitive ones. The possibility of modeling correlated spectral reflectance indices (SRIs) for prediction of different morphological, physiological and root characteristics will be discussed.

Nitrate Starvation Induces Lateral Root Organogenesis in Triticum aestivum via Auxin Signaling.

The lateral root (LR) is an essential component of the plant root system, performing important functions for nutrient and water uptake in plants and playing a pivotal role in cereal crop productivity. Nitrate (NO3-) is an essential nutrient for plants. In this study, wheat plants were grown in 1/2 strength Hoagland's solution containing 5 mM NO3- (check; CK), 0.1 mM NO3- (low NO3-; LN), or 0.1 mM NO3- plus 60 mg/L 2,3,5-triiodobenzoic acid (TIBA) (LNT). The results showed that LN increased the LR number significantly at 48 h after treatment compared with CK, while not increasing the root biomass, and LNT significantly decreased the LR number and root biomass. The transcriptomic analysis showed that LN induced the expression of genes related to root IAA synthesis and transport and cell wall remodeling, and it was suppressed in the LNT conditions. A physiological assay revealed that the LN conditions increased the activity of IAA biosynthesis-related enzymes, the concentrations of tryptophan and IAA, and the activity of cell wall remodeling enzymes in the roots, whereas the content of polysaccharides in the LRP cell wall was significantly decreased compared with the control. Fourier-transform infrared spectroscopy and atomic microscopy revealed that the content of cell wall polysaccharides decreased and the cell wall elasticity of LR primordia (LRP) increased under the LN conditions. The effects of LN on IAA synthesis and polar transport, cell wall remodeling, and LR development were abolished when TIBA was applied. Our findings indicate that NO3- starvation may improve auxin homeostasis and the biological properties of the LRP cell wall and thus promote LR initiation, while TIBA addition dampens the effects of LN on auxin signaling, gene expression, physiological processes, and the root architecture.

Synergistic effect of Pseudomonas putida and endomycorrhizal inoculation on the physiological response of onion (Allium cepa L.) to saline conditions.

Salinity stress negatively affects the growth and yield of crops worldwide. Onion (Allium cepa L.) is moderately sensitive to salinity. Beneficial microorganisms can potentially confer salinity tolerance. This study investigated the effects of endomycorrhizal fungi (M), Pseudomonas putida (Ps) and their combination (MPs) on onion growth under control (0 ppm), moderate (2000 ppm) and high (4000 ppm) NaCl salinity levels. A pot experiment was conducted with sandy loam soil and onion cultivar Giza 20. Results showed that salinity reduced growth attributes, leaf pigments, biomass and bulb yield while increasing oxidative stress markers. However, individual or combined inoculations significantly increased plant height, bulb diameter and biomass production compared to uninoculated plants under saline conditions. MPs treatment provided the highest stimulation, followed by Pseudomonas and mycorrhizae alone. Overall, dual microbial inoculation showed synergistic interaction, conferring maximum benefits for onion growth, bulbing through integrated physiological and biochemical processes under salinity. Bulb yield showed 3.5, 36 and 83% increase over control at 0, 2000 and 4000 ppm salinity, respectively. In conclusion, combined application of mycorrhizal-Pseudomonas inoculations (MPs) effectively mitigate salinity stress. This approach serves as a promising biotechnology for ensuring sustainable onion productivity under saline conditions.

Comparative Long Non-Coding Transcriptome Analysis of Three Contrasting Barley Varieties in Response to Aluminum Stress.

Aluminum toxicity is a major abiotic stress on acidic soils, leading to restricted root growth and reduced plant yield. Long non-coding RNAs are crucial signaling molecules regulating the expression of downstream genes, particularly under abiotic stress conditions. However, the extent to which lncRNAs participate in the response to aluminum (Al) stress in barley remains largely unknown. Here, we conducted RNA sequencing of root samples under aluminum stress and compared the lncRNA transcriptomes of two Tibetan wild barley genotypes, XZ16 (Al-tolerant) and XZ61 (Al-sensitive), as well as the aluminum-tolerant cultivar Dayton. In total, 268 lncRNAs were identified as aluminum-responsive genes on the basis of their differential expression profiles under aluminum treatment. Through target gene prediction analysis, we identified 938 candidate lncRNA-messenger RNA (mRNA) pairs that function in a cis-acting manner. Subsequently, enrichment analysis showed that the genes targeted by aluminum-responsive lncRNAs were involved in diterpenoid biosynthesis, peroxisome function, and starch/sucrose metabolism. Further analysis of genotype differences in the transcriptome led to the identification of 15 aluminum-responsive lncRNAs specifically altered by aluminum stress in XZ16. The RNA sequencing data were further validated by RT-qPCR. The functional roles of lncRNA-mRNA interactions demonstrated that these lncRNAs are involved in the signal transduction of secondary messengers, and a disease resistance protein, such as RPP13-like protein 4, is probably involved in aluminum tolerance in XZ16. The current findings significantly contribute to our understanding of the regulatory roles of lncRNAs in aluminum tolerance and extend our knowledge of their importance in plant responses to aluminum stress.

Commonalities and Specificities in Wheat (Triticum aestivum L.) Responses to Aluminum Toxicity and Low Phosphorus Revealed by Transcriptomics and Targeted Metabolomics.

Aluminum (Al) toxicity and low phosphorus availability (LP) are the top two co-existing edaphic constraints limiting agriculture productivity in acid soils. Plants have evolved versatile mechanisms to cope with the two stresses alone or simultaneously. However, the specific and common molecular mechanisms, especially those involving flavonoids and carbohydrate metabolism, remain unclear. Laboratory studies were conducted on two wheat genotypes-Fielder (Al-tolerant and P-efficient) and Ardito (Al-sensitive and P-inefficient)-exposed to 50 µM Al and 2 µM Pi (LP) in hydroponic solutions. After 4 days of stress, wheat roots were analyzed using transcriptomics and targeted metabolomics techniques. In Fielder, a total of 2296 differentially expressed genes (DEGs) were identified under Al stress, with 1535 upregulated and 761 downregulated, and 3029 DEGs were identified under LP stress, with 1591 upregulated and 1438 downregulated. Similarly, 4404 DEGs were identified in Ardito under Al stress, with 3191 upregulated and 1213 downregulated, and 1430 DEGs were identified under LP stress, with 1176 upregulated and 254 downregulated. GO annotation analysis results showed that 4079 DEGs were annotated to the metabolic processes term. These DEGs were significantly enriched in the phenylpropanoid, flavonoid, flavone and flavonol biosynthesis, and carbohydrate metabolism pathways by performing the KEGG enrichment analysis. The targeted metabolome analysis detected 19 flavonoids and 15 carbohydrate components in Fielder and Ardito under Al and LP stresses. In Fielder, more responsive genes and metabolites were involved in flavonoid metabolism under LP than Al stress, whereas the opposite trend was observed in Ardito. In the carbohydrate metabolism pathway, the gene and metabolite expression levels were higher in Fielder than in Ardito. The combined transcriptome and metabolome analysis revealed differences in flavonoid- and carbohydrate-related genes and metabolites between Fielder and Ardito under Al and LP stresses, which may contribute to Fielder's higher resistance to Al and LP. The results of this study lay a foundation for pyramiding genes and breeding multi-resistant varieties.

PEG treatment is unsuitable to study root related traits as it alters root anatomy in barley (Hordeum vulgare L.).

BACKGROUND: The frequency and severity of abiotic stress events, especially drought, are increasing due to climate change. The plant root is the most important organ for water uptake and the first to be affected by water limitation. It is therefore becoming increasingly important to include root traits in studies on drought stress tolerance. However, phenotyping under field conditions remains a challenging task. In this study, plants were grown in a hydroponic system with polyethylene glycol as an osmotic stressor and in sand pots to examine the root system of eleven spring barley genotypes. The root anatomy of two genotypes with different response to drought was investigated microscopically. RESULTS: Root diameter increased significantly (p < 0.05) under polyethylene glycol treatment by 54% but decreased significantly (p < 0.05) by 12% under drought stress in sand pots. Polyethylene glycol treatment increased root tip diameter (51%) and reduced diameter of the elongation zone (14%) compared to the control. Under drought stress, shoot mass of plants grown in sand pots showed a higher correlation (r = 0.30) with the shoot mass under field condition than polyethylene glycol treated plants (r = -0.22). CONCLUSION: These results indicate that barley roots take up polyethylene glycol by the root tip and polyethylene glycol prevents further water uptake. Polyethylene glycol-triggered osmotic stress is therefore unsuitable for investigating root morphology traits in barley. Root architecture of roots grown in sand pots is more comparable to roots grown under field conditions.

Effects of cadmium stress on the growth and physiological characteristics of sweet potato.

This study evaluated the responses of sweet potatoes to Cadmium (Cd) stress through pot experiments to theoretically substantiate their comprehensive applications in Cd-polluted agricultural land. The experiments included a CK treatment and three Cd stress treatments with 3, 30, and 150 mg/kg concentrations, respectively. We analyzed specified indicators of sweet potato at different growth periods, such as the individual plant growth, photosynthesis, antioxidant capacity, and carbohydrate Cd accumulation distribution. On this basis, the characteristics of the plant carbon metabolism in response to Cd stress throughout the growth cycle were explored. The results showed that T2 and T3 treatments inhibited the vine growth, leaf area expansion, stem diameter elongation, and tuberous root growth of sweet potato; notably, T3 treatment significantly increased the number of sweet potato branches. Under Cd stress, the synthesis of chlorophyll in sweet potato was significantly suppressed, and the Rubisco activity experienced significant reductions. With the increasing Cd concentration, the function of PS II was also affected. The soluble sugar content underwent no significant change in low Cd concentration treatments. In contrast, it decreased significantly under high Cd concentrations. Additionally, the tuberous root starch content decreased significantly with the increase in Cd concentration. Throughout the plant growth, the activity levels of catalase, peroxidase, and superoxide dismutase increased significantly in T2 and T3 treatments. By comparison, the superoxide dismutase activity in T1 treatment was significantly lower than that of CK. With the increasing application of Cd, its accumulation accordingly increased in various sweet potato organs. The the highest bioconcentration factor was detected in absorbing roots, while the tuberous roots had a lower bioconcentration factor and Cd accumulation. Moreover, the transfer factor from stem to petiole was the highest of the potato organs. These results demonstrated that sweet potatoes had a high Cd tolerance and a restoration potential for Cd-contaminated farmland.

Ginseng rusty root symptoms result from nitric oxide stress in soil.

Ginseng, from the roots of Panax ginseng C. A. Meyer, is a widely used herbal medicine in Asian countries, known for its excellent therapeutic properties. The growth of P. ginseng is depend on specific and strict environments, with a preference for wetness but intolerance for flooding. Under excessive soil moisture, some irregular rust-like substances are deposited on the root epidermis, causing ginseng rusty symptoms (GRS). This condition leads to a significant reduce in yield and quality, resulting in substantial economic loses. However, there is less knowledge on the cause of GRS and there are no effective treatments available for its treatment once it occurs. Unsuitable environments lead to the generation of large amounts of reactive oxygen species (ROS). We investigated the key indicators associated with the stress response during different physiological stages of GRS development. We observed a significant change in ROS level, MDA contents, antioxidant enzymes activities, and non-enzymatic antioxidants contents prior to the GRS. Through the analysis of soil features with an abundance of moisture, we further determined the source of ROS. The levels of nitrate reductase (NR) and nitric oxide synthase (NOS) activities in the inter-root soil of ginseng with GRS were significantly elevated compared to those of healthy ginseng. These enzymes boost nitric oxide (NO) levels, which in turn showed a favorable correlation with the GRS. The activities of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase first rose and then decreased as GRS developed. Excess soil moisture causes a decrease in oxygen levels. This activated NR and NOS in the soil, resulting in a production of excess NO. The NO then diffused into the ginseng root and triggered a burst of ROS through NADPH located on the cell membrane. Additionally, Fe2+ in soil was oxidized to red Fe3+, and finally led to GRS. This conclusion was also verified by the Sodium Nitroprusside (SNP), a precursor compound producing NO. The presence of NO from NR and NOS in water-saturated soil is responsible for the generation of ROS. Among these, NO is the main component that contribute to the occurrence of GRS.