Proline Research Articles

Application of Synthetic Microbial Communities of Kalidium schrenkianum in Enhancing Wheat Salt Stress Tolerance.

Soil salinization poses a significant challenge to global agriculture, particularly in arid and semi-arid regions like Xinjiang. Kalidium schrenkianum, a halophytic plant adapted to saline-alkaline conditions, harbors endophytic microorganisms with potential plant growth-promoting properties. In this study, 177 endophytic bacterial strains were isolated from K. schrenkianum, and 11 key strains were identified through functional screening based on salt tolerance, nutrient solubilization, and growth-promoting traits. Synthetic microbial communities (SMCs) were then constructed using these strains and optimized to enhance wheat growth under salt stress. The SMCs significantly improved seed germination, root length, and seedling vigor in both spring and winter wheat in hydroponic and pot experiments. Furthermore, the SMCs enhanced the activities of antioxidant enzymes, including superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and levels of malondialdehyde (MDA) and proline (PRO). They also reduced oxidative stress and improved chlorophyll content in wheat seedlings. These results demonstrate the potential of microbial consortia derived from extreme environments as eco-friendly biofertilizers for improving crop performance in saline soils, offering a sustainable alternative to chemical fertilizers and contributing to agricultural resilience and productivity.

Pumpkin Rootstocks Improve the Low-temperature Resistance of Bitter Gourd through Physiological Regulation

Bitter gourd (Momordica charantia L.) is one of the Cucurbitaceae species that is sensitive to low temperatures. Grafting onto pumpkin rootstock is an effective technique to increase the chilling tolerance of the Cucurbitaceae species upon exposure to low-temperature stress. However, research on the mechanism by which pumpkin rootstock increases chilling tolerance of bitter gourd remains limited. In this study, bitter gourd ‘Baoyu No.2’ was used as the scion, and pumpkin ‘Dongfang Changsheng’ served as the rootstock; self-rooted seedlings are used as a control. The grafted and self-rooted bitter gourd seedlings were exposed to low-temperature stress (10 °C) for 10 days and allowed to recover for 1 day at 25 °C/20 °C (D/N). Changes in chilling damage index, osmotic regulatory substance contents, antioxidant enzyme activity, and chlorophyll fluorescence induction kinetics were determined. We found that the malondialdehyde (MDA) and proline (PRO) levels in the leaves of both self-rooted and grafted bitter gourd seedlings, as well as the activity of antioxidant enzymes, including superoxide dismutase (SOD) and peroxidase (POD), tended to increase overall with increasing duration of low-temperature stress. After 10 days of low-temperature stress, the PRO content of grafted seedlings increased by 312.77% compared with the self-rooted seedlings. The SOD activity increased by 46.19%, and the POD activity increased by 4.66%. Under low-temperature stress, the chlorophyll fluorescence induction kinetics (OJIP) curves of both self-rooted and grafted seedlings clearly changed. As the low-temperature stress duration increased, the maximum fluorescence intensity (P) decreased compared with 0 day, and the J-I-P curve tended to flatten. However, the decline and flattening for grafted seedlings were weaker than those for self-rooted seedlings. After 3 days of low-temperature stress, the Fv/Fm of the self-rooted seedlings reached its lowest point of 0.63, which was 24.10% lower and 18.18% lower than that noted at 0 day and for the grafted seedlings, respectively. The PIABS of the self-rooted seedlings reached its lowest point of 0.61, which was 86.76% lower than that noted at 0 day and 68.88% lower than the grafted seedlings. Furthermore, after 3 days of low-temperature stress, the absorption per active reaction center (ABS/RC) of the self-rooted seedlings increased by 25.19% compared with 0 day and 26.54% compared with the grafted seedlings. Moreover, the dissipation energy per active reaction center (DIo/RC) of the self-rooted seedlings was 179.43% of that noted at 0 day and 108.45% greater than that of the grafted seedlings.

Genome-wide analysis of the cotton COBRA-like gene family and functional characterization of GhCOBL22 in relation to drought tolerance

Abstract Background The COBRA-like (COBL) gene family is a crucial glycosylphosphatidylinositol (GPI)-anchored proteins that participate in various biological processes in plants by regulating the arrangement of cell wall microfibrils. While the functions of COBL genes have been analyzed in several plant species, their roles in cotton’s response to abiotic stress remain unexplored. Results This study identified and characterized the COBL gene family in Gossypium hirsutum, revealing a total of 39 COBL family members classified into five subgroups. Transcriptome analysis indicated that the transcription levels of several GhCOBL genes were upregulated following PEG treatment, with GhCOBL22 being significantly induced. Further silencing of the GhCOBL22 gene through virus-induced gene silencing (VIGS) technology demonstrated that this gene’s silencing reduced cotton’s drought stress tolerance. Under drought stress conditions, the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) enzymes, along with proline (PRO) content, were lower in GhCOBL22-silenced plants compared to control plants, while the accumulation of malondialdehyde (MDA) was significantly higher. Moreover, silencing the GhCOBL22 gene also led to reductions in the levels of cellulose, hemicellulose, and lignin content in cotton leaves. Conclusion A systematic survey of gene structure, motif composition, and evolutionary relationships of the COBL gene family was conducted in Gossypium hirsutum. Subsequent expression and functional studies indicated that GhCOBL22 plays a significant role in cotton’s drought tolerance. These findings enhance our understanding of the biological functions of the COBL family and highlight the critical role of the GhCOBL22 gene in cotton’s response to drought stress.

Highland barley ELNs and physiological responses to different concentrations of Cr (VI) stress.

This study is the first to use highland barley (HB) to study the toxic effects of Cr (VI) on seedlings and the response mechanism of HELNs to Cr (VI) stress. The outcomes indicated that the germination rate of HB seeds, plant height, root length, water content, and levels of proline (PRO) and soluble sugar in both leaves and roots were all impacted by varying concentrations of Cr (VI) treatments. Differential changes in the activities of antioxidant enzymes (SOD, POD, CAT) were observed in leaves and roots of HB. We also extracted HB-derived ELNs (HELNs) and characterized and sequenced HELNs. The average particle size of CK-HELNs was 79.0 nm, and the concentration of HELNs was 4.56 E+10 (particles/mL). As the concentration of Cr (VI) increased, the particle size of HELNs in HB seedlings also increased, while the concentration decreased. A total of 29 miRNA species were identified in CK-HELNs, Cr10-HELNs, and Cr40-HELNs. Out of these, 25 were newly predicted miRNAs, and the remaining four were known miRNAs. A total of 2 known miRNAs and 11 novel miRNAs were upregulated under different concentrations of Cr (VI) stress. 1 known and 5 novel miRNAs were downregulated under different concentrations of Cr (VI) stress. Enrichment of the GO and KEGG pathways revealed that the differential gene functions were mainly focused on binding and catalytic activities. This study reveals for the first time the changes of HELNs under different concentrations of Cr (VI) stress and the toxic effects of Cr (VI) on HB seedlings. This study provides a new perspective to explore the function and utilisation of ELNs.

Effect of exogenous application of L-mimosine on physiological, cytogenetic, biochemical and anatomical characteristics of Allium cepa L

Mimosine [β-(3‑hydroxy-4-pyridone-1-yl)-l-alanine] is a toxic non- protein amino acid, and one of its major effects is to suppress plant growth and development. Since mimosine is a compound responsible for many interesting biological activities, intensive studies have begun to be carried out on it in recent years. The current work investigated toxic effects of exogenously given 1, 2 and 3 mM l-mimosine doses on some physiological, cytogenetic, biochemical, and anatomical parameters of Allium cepa L. bulbs. For this purpose, the germination percentage (GP), root length (RL), root number (RN), and fresh weight (FW) were determinated as physiological parameters to be examined experimentally; the micronucleus (MN) frequency, chromosomal aberrations (CAs), and mitotic index (MI) were chosen as cytogenetic parameters; and the catalase (CAT) and superoxide dismutase (SOD) activities, malondialdehyde (MDA) level, and free proline (PR) content were determinated as biochemical parameters to be investigated. In addition, the changes in the root anatomical structure of the bulbs were examined under the microscope by taking cross-sections. Onion bulbs were divided into four groups as three treatments and one control (C). For seven days, the bulbs in the treatment groups were germinated with three different doses of l-mimosine (1, 2 and 3 mM), while the bulbs in the C group were germinated with tap water. Consequently, all three doses of l-mimosine caused a decrease (p < 0.05) in all investigated physiological parameter (GP, RL, RN and FW) values compared to C. Furthermore, every l-mimosine dosage resulted in a reduce (p < 0.05) in MI and an increase (p < 0.05) in MN and CA frequency compared to C group. l-mimosine application promoted CAs such as irregular mitosis, stick chromosome, lagging chromosome, protruded out chromosome, pole deviation and alignment in root meristem cells. Exposure to l-mimosine resulted in dose-related increases (p < 0.05) in SOD and CAT enzyme activity as well as MDA and PR levels compared to C group, indicating that l-mimosine also induced toxicity by causing oxidative stress in cells. Also, especially exposure to a dose of 3 mM l-mimosine caused the anatomical damages such as deformations of the epidermis and cortex cells, necrosis, buildup of certain chemical compounds in the cortex cells, thickening of the cortex cell wall, formation of vacuoles in the cell nuclei and flattened cell nuclei in the root tip meristem cells. In summary, since l-mimosine showed an inhibitory effect in the Allium cepa L. test material, it was concluded that the compound induced multi-dimensional toxicity, and the Allium test proved to be a highly valuable tool in identifying this toxicity.

Genotype and Organ-Specific Variability in Antioxidant Capacities as Well as Polyamine and Osmolyte Levels in Eleven Lisianthus (Eustoma grandiflorum Raf.) Cultivars with Different Flowering Periods

Lisianthus (Eustoma grandiflorum Raf. Shinn.) is a valued plant known for its diverse flower colors and long vase life. Despite considerable research on the physiological roles of osmolytes, polyamines, and phenolic compounds, there is a lack of understanding regarding their specific accumulation patterns across various lisianthus cultivars and organs. This study aims to compare eleven lisianthus cultivars with varying flowering periods according to their accumulation of osmolytes, polyamines, phenolic content, and antioxidant capacities and measure their resistance to abiotic stress factors. High-performance liquid chromatography coupled with fluorescent detection was employed to quantify putrescine (PUT), spermidine (SPD), and spermine (SPM). In addition, proline (PRO), glycine betaine (GB), antioxidant capacities, phenolic content, and flavonoid contents were assessed spectrophotometrically. This comprehensive analysis allowed for a detailed understanding of the biochemical markers. The result indicates a significant genotype and organ-dependent variation in accumulation patterns of inspected metabolites and antioxidant activities. The petals of Rosita Green exhibited the highest levels of phenols and flavonoids, whereas the petals of Rosita Blue Picote demonstrated the highest concentrations of osmolytes. Polyamines were found to be more concentrated in the petals than in the leaves. The average values indicated high levels of polyamines in the Mariachi Carmine (PUT 186.72 nmol g−1 DW) and Mariachi Pink (SPD 227.4 nmol g−1 DW) cultivars. These findings underscore the significance of inspected compounds in stress tolerance among cultivars with different flowering periods, providing insights for optimizing cultivation strategies for lisianthus.

Anion Receptor-manipulated solvation chemistry and electric double layer enables high Zn-Utilization rate and lean Zn metal batteries

The practical application of aqueous Zn metal batteries (AZMBs) is impeded by inferior reversibility and stability of Zn metal anode (ZMA) originated from side reactions and dendrite growth. Herein, anion receptor l-Proline (LP) is selected to simultaneously manipulate solvation chemistry and electric double layer (EDL) for constructing dendrite-free and stable AZMBs with an ultra-high depth of discharge (DOD of 100 %) and low negative/positive capacity ratio (N/P of 1.1). Experimental and computational results demonstrate that the strong interaction between −SO32- group from OTf- anion and LP promotes the coordination effect of cation and solvent, which improves the stability of electrolyte and induces fine and uniform Zn nucleus formation. Meanwhile, the preferential reduction of OTf- and adsorption of LP establish an anion-derived ZnF2-rich solid electrolyte interface by altering EDL structure, which enhances the mechanical stability and Zn2+ diffusion kinetics of the interface and prevents the contact of H2O molecules. Consequently, ZMA in LP/Zn(OTf)2 electrolyte delivers a satisfactory cycling lifespan under DOD of 100 % and an outstanding Coulombic efficiency of 99.93 % for 10,000 cycles at 10 mA cm−2. Moreover, Zn||Od-NH4V4O10 full cells with LP/Zn(OTf)2 electrolyte demonstrate excellent cycle stability at high cathode loading (20.412 mg), low N/P (1.1), and high temperature (50 °C).

Facilitating effects of plant extracts on soil health and replanted Panax ginseng growth in recession soil.

Plant extracts have been shown to be effective agricultural strategies for improving soil fertility and quality, and promoting plant growth in soil degradation remediation. The application of plant extracts improves the material cycle of soil microecology, such as the decomposition of nitrogen, phosphorus, and potassium, while increasing plant resistance. However, there is currently no experiment to demonstrate whether plant extracts have a promoting effect on the growth of ginseng and the mechanism of action. Pot experiments were carried out to investigate the effects of extracts, namely Rubia cordifolia (RC), Schisandra chinensis (SC), and Euphorbia humifusa (EH) on soil properties, enzyme activities, and plant physiological characteristics were evaluated. Results showed that compared with CK, plant extract-related treatments increased soil Organic carbon (OC), Available nitrogen (AN), Available phosphorus (AP) contents, and Soil urease activity. (S-UE), Soil sucrase activity (Soil sucrase), Soil acid phosphatase activity. (S-ACP). Meanwhile, plant extract-related treatments significantly increased plant physiological properties and TP (Total protein) content, and decreased the content of MDA (malondialdehyde) by 15.70% -36.59% and PRO (proline) by 30.13% -148.44%. Furthermore, plant extract-related treatments also significantly promote plant growth and reduce plant incidence, the fresh weight of ginseng increased by 27.80% -52.08%, ginseng root activity increased by 45.13% -90.07%, and ginseng incidence rate decreased by 20.00% -46.67%. Through correlation analysis between fresh weight of ginseng and root parameters and soil index, fresh weight is significantly positively correlated with root diameter, fiber root number, root activity, total protein (TP), catalytic activity (CAT) and superoxide dismutase activity (SOD), H, soil urea activity (S-UE), soil sucrose activity (S-SC), soil acid phosphate activity (S-ACP), and soil laccase activity (SL); The fresh weight was significantly negatively correlated with incidence rate, disease severity index, and malondialdehyde content (MDA). In summary, plant extract-related treatments improve soil quality and promote ginseng growth, further enhancing soil health and plant disease resistance. These findings provide new insights into ginseng cultivation and soil health management and highlight a new approach that can be applied to a wider range of agricultural practices and environmental sustainability.

Exogenous Substances Improved Salt Tolerance in Cotton

Soil salinization is a major limiting factor for cotton growth in Southern Xinjiang. Studying technologies and mechanisms to improve cotton salt tolerance is of significant importance for the development and utilization of saline–alkaline land. In this study, ‘Xinluzhong 40’ cotton was used as the material, and 150 mmol·L−1 sodium chloride (NaCl) and 1.2% natural saline–alkaline soil extract were employed to simulate single-salt (SS) and mixed-salt (MS) stresses, respectively. The effects of different exogenous substances (sodium nitrophenolate, 24-epibrassinolide, and γ-aminobutyric acid) on the growth characteristics of cotton under salt stress were investigated. The results show that: (1) Under salt stress, the height and biomass of cotton (50 d old) were reduced. Both SS and MS stresses led to increased superoxide dismutase (SOD) activity, elevated proline (PRO) content (with an increase of 50.01% and no significant difference), and increased malondialdehyde (MDA) content (with increases of 63.14% and 32.42%, respectively). At the same time, catalase (CAT) activity decreased, Na+ and Cl− contents increased, K+ content decreased, and the K+/Na+ ratio was reduced. (2) Application of sodium nitrophenolate (S), 24-epibrassinolide (E), and γ-aminobutyric acid (G) significantly improved SOD activity and PRO content while reducing MDA content (decreased by 29.33%, 25.48%, and 30.47% compared to SS treatment; and 1.68%, 5.21%, and 5.49% compared to MS treatment, respectively). They also increased CAT activity (increased by 75.97%, 103.24%, and 80.79% compared to SS treatment; and 91.06%, 82.43%, and 119.68% compared to MS treatment, respectively) and K+/Na+ ratio (increased by 57.59%, 66.35%, and 70.50% compared to SS treatment; and 38.31%, 42.97%, and 66.66% compared to MS treatment, respectively), reduced Cl− content, and promoted increases in plant height and biomass. The effects of exogenous substances on antioxidant capacity and ion balance under salt stress were significant, particularly under SS stress. (3) Principal component analysis revealed that under SS and MS stresses, principal component 1 mainly reflects cotton’s antioxidant capacity, with SOD, CAT, and PRO having high weights; principal component 2 mainly reflects cotton’s ion balance and nutrient absorption, with root Na+, stem Na+, leaf Na+, root K+, and root Cl− having high weights. These findings highlight the potential of exogenous substances to improve cotton salt tolerance and provide scientific evidence for cotton cultivation on saline–alkaline land, offering new insights into cultivation techniques from an applied research perspective.

Overexpression of StERECTA enhances drought tolerance in Arabidopsis thaliana

Drought is a major abiotic stresses that severely hinder plant growth and agricultural productivity. The receptor-like kinase gene, ERECTA, has been proved to play important role in promoting the response to abiotic stress in crops. However, the specific molecular mechanisms underlying the drought resistance mediated by ERECTA in potato (Solanum tuberosum L.) are not well understood. In this study, sequence analysis confirmed that the StERECTA gene contains eight leucine-rich repeat (LRR) domains and an S_TKc domain, and these domains were highly conserved in Solanaceae family. Under drought stress, Arabidopsis thaliana strains overexpressing StERECTA showed increased biomass, proline (PRO) content, and antioxidant enzyme activities compared to the wild-type strains while the mutant ERECTA strain (er105) exhibited opposite phenotype. Additionally, StERECTA overexpression upregulated the expression of drought response marker genes (LEA3, DREB2A and P5CS1), improved levels of ABA and auxin, reduced stomatal density and relative expression level of stomatal development related genes (SPCH, FAMA and MUTE). Furthermore, Co-immunoprecipitation (Co-IP) assays demonstrated that StERECTA physically interacted with the YODA protein. In conclusion, our study provides new insights into the role and regulatory mechanism of StERECTA in response to drought stress. These findings may serve as a basis for genetic improvement of potato to enhance their tolerance to abiotic stress.

Cloning and Functional Study of AmGDSL1 in Agropyron mongolicum.

Agropyron mongolicum Keng is a diploid perennial grass of triticeae in gramineae. It has strong drought resistance and developed roots that can effectively fix the soil and prevent soil erosion. GDSL lipase or esterases/lipase has a variety of functions, mainly focusing on plant abiotic stress response. In this study, a GDSL gene from A. mongolicum, designated as AmGDSL1, was successfully cloned and isolated. The subcellular localization of the AmGDSL1 gene (pCAMBIA1302-AmGDSL1-EGFP) results showed that the AmGDSL1 protein of A. mongolicum was only localized in the cytoplasm. When transferred into tobacco (Nicotiana benthamiana), the heterologous expression of AmGDSL1 led to enhanced drought tolerance. Under drought stress, AmGDSL1 overexpressing plants showed fewer wilting leaves, longer roots, and larger root surface area. These overexpression lines possessed higher superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and proline (PRO) activities. At the same time, the malondialdehyde (MDA) content was lower than that in wild-type (WT) tobacco. These findings shed light on the molecular mechanisms involved in the GDSL gene's role in drought resistance, contributing to the discovery and utilization of drought-resistant genes in A. mongolicum for enhancing crop drought resistance.

Inter-subspecies diversity of maize to drought stress with physio-biochemical, enzymatic and molecular responses.

Drought is the most significant factor limiting maize production, given that maize is a crop with a high water demand. Therefore, studies investigating the mechanisms underlying the drought tolerance of maize are of great importance. There are no studies comparing drought tolerance among economically important subspecies of maize. This study aimed to reveal the differences between the physio-biochemical, enzymatic, and molecular mechanisms of drought tolerance in dent (Zea mays indentata), popcorn (Zea mays everta), and sugar (Zea mays saccharata) maize under control (no-stress), moderate, and severe drought stress. Three distinct irrigation regimes were employed to assess the impact of varying levels of drought stress on maize plants at the V14 growth stage. These included normal irrigation (80% field capacity), moderate drought (50% field capacity), and severe drought (30% field capacity). All plants were grown under controlled conditions. The following parameters were analyzed: leaf relative water content (RWC), loss of turgidity (LOT), proline (PRO) and soluble protein (SPR) contents, membrane durability index (MDI), malondialdehyde (MDA), and hydrogen peroxide (H2O2) content, the antioxidant enzyme activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), and catalase (CAT). Additionally, the expression of heat shock proteins (HSPs) was examined at the transcriptional and translational levels. The effects of severe drought were more pronounced in sugar maize, which had a relatively high loss of RWC and turgor, membrane damage, enzyme activities, and HSP90 gene expression. Dent maize, which is capable of maintaining its RWC and turgor in both moderate and severe droughts, and employs its defense mechanism effectively by maintaining antioxidant enzyme activities at a certain level despite less MDA and H2O2 accumulation, exhibited relatively high drought tolerance. Despite the high levels of MDA and H2O2 in popcorn maize, the up-regulation of antioxidant enzyme activities and HSP70 gene and protein expression indicated that the drought coping mechanism is activated. In particular, the positive correlation of HSP70 with PRO and HSP90 with enzyme activities is a significant result for studies examining the relationships between HSPs and other stress response systems. The discrepancies between the transcriptional and translational findings provide an opportunity for more comprehensive investigations into the role of HSPs in stress conditions.

Seed priming with mepiquat chloride and foliar applications of salicylic acid and proline improve the adverse effects of water deficit in cotton (Gossypium hirsutum L.)

We aimed to investigate the effects of some seed priming and foliar applications on stress prevention in cotton under deficit irrigation conditions. Seed priming with mepiquat chloride (PIX) and foliar applications of salicylic acid (SA) and proline (PRO) were tested at three levels of irrigation at 25, 50, and 100% of field capacity. Plant height, boll number, fiber length and fiber strength were significantly affected by the interaction of irrigation level × treatment. The effects of irrigation level and treatment were significant for boll weight, seed index, seed cotton yield and lint yield. When deficit irrigation conditions (25%) were compared with full irrigation, plant height decreased by 21.6 %, boll number by 18.1 %, boll weight by 26.0%, seed index by 5.8%, seed cotton yield by 25.6% and lint yield by 24.6%. Seed priming with PIX and foliar application of PRO produced significantly higher seed cotton and lint yields, whereas SA application had favourable fiber quality parameters under deficit irrigation conditions. PRO slightly increased fiber fineness. Foliar application of SA positively affected chlorophyll content (SPAD) and leaf area index (LAI) under deficit irrigation. In conclusion, it was recommended that all three practices could be successfully used to alleviate negative impacts under deficit irrigation conditions.

Evaluation with physiological, cytogenetic, biochemical and anatomical aspects of dose-dependent inhibitory activity of jasmonic acid, a lipidderived growth regulator, in onion root tip cells

The effects of different doses of exogenous jasmonic acid (JA), were investigated on physiological parameters such as germination percentage, root length, root number and fresh weight, cytogenetic parameters such as mitotic index (MI), micronucleus (MN), frequency and chromosome aberration (CA), biochemical parameters as such superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA) and proline (PR) contents of Allium cepa L., known as onion. In addition, the changes in the root anatomical structures of the bulbs were examined under the microscope by taking cross-sections. Onion bulbs were divided into four groups as one control (C) and three treatments. The bulbs of the C group were kept in cuvettes containing tap water for 7 days and the bulbs of the treatment groups were kept in cuvettes containing 100 µM, 250 µM and 500 µM JA. JA administration caused a decrease in all physiological parameters examined, an increase in the frequency of MN and CA, and a reduce in MI compared to group C. In addition, the mentioned application caused a dosedependent increase in CAT and SOD activities and MDA and PR contents compared to group C. Moreover, 500 µM JA, the highest application dose, caused quite significant damages such as giant cell nucleus, unclear vascular tissue, binuclealar cell and accumulation of some substances in the cells of the epidermis/cortex in root anatomical structure of the bulbs. In summary, it was concluded that JA is a chemical with inhibitory functions and the Allium cepa test is a useful bioindicator for monitoring these effects.

Comprehensive evaluation of drought tolerance of six Chinese chestnut varieties (clones) based on flavonoids and other physiological indexes

Flavonoids are crucial secondary metabolites that possess the ability to mitigate UV damage and withstand both biotic and abiotic stresses. Therefore, it is of immense significance to investigate the flavonoid content as a pivotal indicator for a comprehensive assessment of chestnut's drought tolerance. This study aimed to determine the flavonoid content and drought tolerance-related physiological and biochemical indices of six chestnut varieties (clones) grafted trees—Qianxi 42 (QX42), Qinglong 45 (QL45), Yanshanzaofeng (YSZF), Yanzi (YZ), Yanqiu (YQ), and Yanlong (YL)-under natural drought stress. The results were used to comprehensively analyze the drought tolerance ability of these varieties. The study revealed that the ranking of drought tolerance indices in terms of their ability to reflect drought tolerance was as follows: superoxide (oxide) dismutase (SOD) activity, ascorbate peroxidase (APX) activity, flavone content, catalase (CAT) activity, proline (PRO) content, soluble sugar content, peroxidase (POD) activity, betaine content, flavonol content, hydrogen peroxide (H2O2) content, soluble protein content, superoxide ion (OFR) content, superoxide (ion OFR) production rate, malondialdehyde (MDA) content, chlorophyll content. Through principal component analysis, the contents of flavonoids and flavonols can be used as indicators for comprehensive evaluation of drought tolerance of chestnut. The comprehensive evaluation order of drought tolerance of grafted trees of 6 chestnut varieties (Clones) was: QL45 > QX42 > YQ > YZ > YSZF > YL.

Physiological and Transcriptome Analyses Reveal the Protective Effect of Exogenous Trehalose in Response to Heat Stress in Tea Plant (Camellia sinensis).

It is well known that application of exogenous trehalose can enhance the heat resistance of plants. To investigate the underlying molecular mechanisms by which exogenous trehalose induces heat resistance in C. sinensis, a combination of physiological and transcriptome analyses was conducted. The findings revealed a significant increase in the activity of superoxide dismutase (SOD) and peroxidase (POD) upon treatment with 5.0 mM trehalose at different time points. Moreover, the contents of proline (PRO), endogenous trehalose, and soluble sugar exhibited a significant increase, while malondialdehyde (MDA) content decreased following treatment with 5.0 mM trehalose under 24 h high-temperature stress (38 °C/29 °C, 12 h/12 h). RNA-seq analysis demonstrated that the differentially expressed genes (DEGs) were significantly enriched in the MAPK pathway, plant hormone signal transduction, phenylpropanoid biosynthesis, flavone and flavonol biosynthesis, flavonoid biosynthesis, and the galactose metabolism pathway. The capability to scavenge free radicals was enhanced, and the expression of a heat shock factor gene (HSFB2B) and two heat shock protein genes (HSP18.1 and HSP26.5) were upregulated in the tea plant. Consequently, it was concluded that exogenous trehalose contributes to alleviating heat stress in C. sinensis. Furthermore, it regulates the expression of genes involved in diverse pathways crucial for C. sinensis under heat-stress conditions. These findings provide novel insights into the molecular mechanisms underlying the alleviation of heat stress in C. sinensis with trehalose.

Comprehensive physiology and proteomics analysis revealed the resistance mechanism of rice (Oryza sativa L) to cadmium stress

Cadmium contamination can lead to a decrease in crop yield and quality. However, Cd-tolerant rice can improve rice resistance genes, improve crop tolerance to heavy metals, and protect plants from oxidative damage. In this study, Japonica rice: Chunyou 987 and Indica rice: Chuanzhong you 3607 were used to reveal the molecular response mechanism of Cd-tolerant rice under cadmium concentration of 3 mg/kg through comparative experiments combined with physiology and proteomics. The results showed that compared with indica rice, japonica rice showed more robust resistance to Cd stress and effectively retained many Cd ions in roots. Moreover, it enhanced its enzymatic and non-enzymatic anti-oxidative stress mechanism, which increased the activities of catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD) by 47.37%, 21.75%, and 55.42%, respectively. The contents of non-enzymatic antioxidant substances ascorbic acid (AsA), glutathione (GSH), cysteine (Cys), proline (PRO), anthocyanins (OPC), and flavonoids were increased by 25.32%, 42.67%, 21.43%, 50.81%, 33.23%, and 72.16%, respectively. Through proteomics analysis, it was found that in response to the damage caused by cadmium stress, Japonica rice makes Photosynthesis functional proteins (psbO and PetH), Photosynthesis antenna proteins (LHCA and ASCAB9), Carbon fixation functional proteins (PEPC and OsAld), Porphyrin metabolism functional proteins (OsRCCR1 and SE5), Glyoxylate and dicarboxylate The expression of metabolism functional proteins (CATC and GLO4.) and Glutathione metabolism functional proteins (APX8 and OsGSTU13) were significantly up-regulated, which stimulated the antioxidant stress mechanism and photosynthetic system, and constructed a robust energy supply system to ensure the normal metabolic activities of life. Strengthening the mechanisms of plant homeostasis. In summary, this study revealed the molecular mechanism of tolerance to Cd stress in japonica rice, and the results of this study will provide a possible way to improve Cd-resistant rice seedlings.

Comparative Physio-Biochemical and Transcriptome Analyses Reveal Contrasting Responses to Magnesium Imbalances in Leaves of Mulberry (Morus alba L.) Plants.

Magnesium (Mg) deficiency is a major factor limiting the growth and development of plants. Mulberry (Morus alba L.) is an important fruit tree crop that requires Mg for optimal growth and yield, especially in acid soils. However, the molecular mechanism of Mg stress tolerance in mulberry plants remains unknown. In this study, we used next-generation sequencing technology and biochemical analysis to profile the transcriptome and physiological changes of mulberry leaves under different Mg treatments (deficiency: 0 mM, low: 1 mM, moderate low: 2 mM, sufficiency: 3 mM, toxicity: 6 mM, higher toxicity: 9 mM) as T1, T2, T3, CK, T4, T5 treatments, respectively, for 20 days. The results showed that Mg imbalance altered the antioxidant enzymatic activities, such as catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD), and non-enzymatic, including soluble protein, soluble sugar, malondialdehyde (MDA), and proline (PRO), contents of the plant. The Mg imbalances disrupted the ultrastructures of the vital components of chloroplast and mitochondria relative to the control. The transcriptome data reveal that 11,030 genes were differentially expressed (DEGs). Genes related to the photosynthetic processes (CAB40, CAB7, CAB6A, CAB-151, CAP10A) and chlorophyll degradation (PAO, CHLASE1, SGR) were altered. Antioxidant genes such as PER42, PER21, and PER47 were downregulated, but DFR was upregulated. The carbohydrate metabolism pathway was significantly altered, while those involved in energy metabolism processes were perturbed under high Mg treatment compared with control. We also identified several candidate genes associated with magnesium homeostasis via RT-qPCR validation analysis, which provided valuable information for further functional characterization studies such as promoter activity assay or gene overexpression experiments using transient expression systems.

Modification of amino functionalized silica nanoparticles with L-proline and furanacrylic acid as novel composites for the efficient removal of methyl orange

The present study deals with the preparation of new composites in which L-proline (LP) and furnacrylic acid (FA) have been grafted on surface of amino functionalized silica nanoparticles (AFS). At first, AFS were prepared by sol-gel approach using tetraethoxysilane (TEOS) as silica source and aminopropyltriethoxysilane (APTES) as silica modifiers. Taking the advantage of amino group on AFS surface, LP and FA were easily grafted on silica surface to obtain LP grafted silica (AFS-LP) and FA grafted silica (AFS-FA) nanocomposites by post modification approach. As prepared composites were characterized by FTIR, SEM, XRD and TGA. The evidence of LP and FA on AFS was elucidated from the FTIR bands found at 1650–1698 cm−1 related to carbonyl group CO) of amide. Additionally, peaks observed at 2965 cm−1 (C-H stretching) of propyl groups and at 1050 cm−1 (Si-O-Si) indicated that the backbone of the material is preserved as silica. The micro images of SEM depicted that the AFS are spherical in shape and have more degree of monodispersivity whereas the SEM images of composites (AFS-LP and AFS-FA) have larger particle size and less degree of monodispersivity. Likewise, XRD peaks at 2θ (∼12°) revealed the mesoporosity of silica as well as hybrid silica and further depression in this peak in case of AFS-LP and AFS-FA depicted the existence of organic moieties on silica. TGA analysis depicted three decomposition steps (high weight loss) in case of AFS-LP and AFS-FA in contrast to two decomposition steps observed in case of AFS. The higher weight loss observed in the case of hybrid composites depicted the grafting of organic molecules on AFS. The prepared composites AFS-LP and AFS-FA were deployed to investigate their adsorption capacity to remove methyl orange (MO) from aqueous media. Experiments revealed that the composites have high adsorption capacity in acidic media (pH=2) with % removal of 85.05 % for AFS-LP and 81.70 % for AFS-FA. The experimental data was evaluated for adsorption isotherms and value of correlation factor (R2) was close to unity in case of Freundlich representing that the adsorption follows Freundlich isotherm. The data was also evaluated for kinetic models and higher values of R2 as well as closeness of experimental and calculated values of Qe predicted that adsorption of MO followed pseudo-second order kinetic model.

Enhancing the growth performance of Sesbania cannabina using Ensifer alkalisoli and biochar under salt stress

Sesbania cannabina is a leguminous salt-tolerant plant that has been effectively used in saline-alkaline land restoration, and forms symbiotic interactions with various rhizobia to form nodules. Ensifer alkalisoli YIC4027, a rhizobium, was screened from S. cannabina root nodules and has significant host specificity. However, the mechanism underlying the symbiotic salt tolerance of S. cannabina -YIC4027, and strategies to enhance this tolerance remain poorly understood. In this study, the mechanism underlying the effect of YIC4027 on the salt tolerance of S. cannabina and the effect of straw biochar on the symbiotic nodulation of S. cannabina-YIC4027 under salt stress were analyzed using a vermiculite pot test. The results indicated that inoculation with YIC4027 markedly increased the biomass, chlorophyll content, photosynthetic rate, superoxide dismutase (SOD) activity and catalase (CAT) activity of S. cannabina under salt stress, while there was no obvious change in glutathione (GSH) or proline (PRO) content. The nitrogen supply and salt concentration are important regulators of YIC4027 nodulation. Salt stress reduced the nodulation efficiency of YIC4027 by 66.67%, and straw biochar application resulted in a 5-fold increase in nodulation efficiency of YIC4027. The present results further suggest that the combination of YIC4027 and straw biochar is an effective biological method for enhancing the effectiveness of S. cannabina in saline-alkali soil improvement.