Effect of drought on photosynthesis, total antioxidant capacity, bioactive component accumulation, and the transcriptome of Atractylodes lancea

Exogenous Melatonin Modulates Photosynthesis and Antioxidant Systems for Improving Drought Tolerance of Sorghum Seedling

Sorghum faces significant production challenges due to drought stress. Melatonin has been demonstrated to play a crucial role in coping with stresses in plants. This study investigated the effect of exogenous melatonin on the sorghum seedling growth, photosynthetic capacity, and antioxidant system under drought stress. The results indicated that drought stress inhibited the growth of sorghum seedlings by a marked reduction in leaf relative water content, along with a significant increase in both malondialdehyde and hydrogen peroxide content. The drought stress also led to a significant diminution in chlorophyll contents, thereby curtailing the capacity for light energy capture. Furthermore, the efficiency of the photosynthetic electron transport chain was adversely impacted. However, the application of exogenous melatonin notably mitigated the adverse effects on sorghum seedlings under the drought stress. Additionally, it stimulated an elevation in the photosynthetic rate and a decrease in non-photochemical quenching. The exogenous melatonin also facilitated the preservation of the chloroplast ultra-structure and boosted the activity of antioxidant enzymes and the content of non-enzymatic antioxidants. Cluster heat maps and principal component analysis further revealed significant correlations among various parameters under different treatment conditions. These results highlight melatonin's role in improving sorghum's drought tolerance, which is beneficial for agricultural management.

Potassium silica nanostructure improved growth and nutrient uptake of sorghum plants subjected to drought stress

Introduction

Recent advancements in nanotechnology present promising opportunities for enhancing crop resilience in adverse environmental conditions.

Methods

In this study, we conducted a factorial experiment to investigate the influence of potassium nanosilicate (PNS) on sorghum plants exposed to varying degrees of drought stress A randomized complete block design with three replications was employed to subject the sorghum plants to different drought conditions. The three levels of stress were designated as non-stress (NS at -0.03 MPa), moderate stress (MD at -0.6 MPa), and severe stress (SD at -1.2 MPa). The plants were administered PNS at concentrations of 0 mM (control), 3.6 mM Si, and 7.2 mM Si.

Results and discussion

As drought stress intensified, we observed significant reductions in multiple plant parameters, including height, fresh weight, dry weight, leaf number, stem diameter, cluster length, seed weight, and nutrient uptake, with the most pronounced effects observed under SD conditions. Interestingly, nitrogen (N) and potassium (K) levels exhibited an increase under drought stress and PNS application, peaking at MD, alongside Si concentrations. Notably, PNS application facilitated enhanced nutrient uptake, particularly evident in the significant increase in nitrogen concentration observed at 3.6 mM PNS. Furthermore, the application of PNS significantly enhanced the fresh weight and nutrient concentrations (notably K and Si) in sorghum seeds under drought stress, despite varying statistical significance for other nutrients. These findings shed light on the mechanisms through which PNS exerts beneficial effects on plant performance under drought stress. By elucidating the complex interactions between PNS application, drought stress, and plant physiology, this study contributes significantly to the development of sustainable agricultural practices aimed at bolstering crop resilience and productivity in water-limited environments.

GOA-optimized deep learning for soybean yield estimation using multi-source remote sensing data

Accurately estimating large-area crop yields, especially for soybeans, is essential for addressing global food security challenges. This study introduces a deep learning framework that focuses on precise county-level soybean yield estimation in the United States. It utilizes a wide range of multi-variable remote sensing data. The model used in this study is a state-of-the-art CNN-BiGRU model, which is enhanced by the GOA and a novel attention mechanism (GCBA). This model excels in handling intricate time series and diverse remote sensing datasets. Compared to five leading machine learning and deep learning models, our GCBA model demonstrates superior performance, particularly in the 2019 and 2020 evaluations, achieving remarkable R2, RMSE, MAE and MAPE values. This sets a new benchmark in yield estimation accuracy. Importantly, the study highlights the significance of integrating multi-source remote sensing data. It reveals that synthesizing information from various sensors and incorporating photosynthesis-related parameters significantly enhances yield estimation precision. These advancements not only provide transformative insights for precision agricultural management but also establish a solid scientific foundation for informed decision-making in global agricultural production and food security.

Drought Stress Responses in Arabica Coffee Genotypes: Physiological and Metabolic Insights

Understanding the impact of drought stress on Arabica coffee physiology and metabolism is essential in the pursuit of developing drought-resistant varieties. In this study, we explored the physiological and metabolite changes in coffee genotypes exhibiting varying degrees of tolerance to drought-namely, the relatively tolerant Ca74110 and Ca74112, and the sensitive Ca754 and CaJ-19 genotypes-under well-watered conditions and during terminal drought stress periods at two time points (0 and 60 days following the onset of stress). The metabolite profiling uncovered significant associations between the growth and the physiological characteristics of coffee genotypes with distinct drought tolerance behaviors. Initially, no marked differences were observed among the genotypes or treatments. However, at the 60-day post-drought onset time point, notably higher shoot growth, biomass, CO2 assimilation, pigments, and various physiological parameters were evident, particularly in the relatively tolerant genotypes. The metabolite profiling revealed elevations in glucose, maltose, amino acids, and organic acids, and decreases in other metabolites. These alterations were more pronounced in the drought-tolerant genotypes, indicating a correlation between enhanced compatible solutes and energy-associated metabolites crucial for drought tolerance mechanisms. This research introduces GC-MS-based metabolome profiling to the study of Ethiopian coffee, shedding light on its intricate responses to drought stress and paving the way for the potential development of drought-resistant coffee seedlings in intensified agro-ecological zones.

Photosynthetic gas exchange, plant water relations and osmotic adjustment of three tropical perennials during drought stress and re-watering

Planting vegetation on slopes is an effective way of improving slope stability while enhancing the aesthetic appearance of the landscape. However, plants growing on slopes are susceptible to natural drought stress (DS) conditions which commonly lead to water deficit in plant tissues that affect plant health and growth. This study investigated the photosynthetic gas exchange, plant water status and proline accumulation of three tropical perennials namely Clerodendrum paniculatum, Ipomoea pes-caprae and Melastoma malabathricum after being subjected to DS and re-watering (RW). During DS, there was a significant decrease in light-saturated photosynthetic CO2 assimilation rate (Asat), stomatal conductance (gs sat), and transpiration rate (Tr) for all three plant species. Leaf relative water content, shoot water potential, and leaf, stem and root water content also declined during DS. Proline concentration increased for all three species during DS, reaching especially high levels for C. paniculatum, suggesting that it heavily relies on the accumulation of proline to cope with DS. Most of the parameters recovered almost completely to levels similar to well-watered plants after RW, apart from M. malabathricum. Strong linear correlations were found between Asat and gs sat and between gs sat and Tr. Ultimately, C. paniculatum and I. pes-caprae had better drought tolerance than M. malabathricum.

Transcriptomic and physiological analysis of atractylodes chinensis in response to drought stress reveals the putative genes related to sesquiterpenoid biosynthesis

BACKGROUND

Atractylodes chinensis (DC) Koidz., a dicotyledonous and hypogeal germination species, is an important medicinal plant because its rhizome is enriched in sesquiterpenes. The development and production of A. chinensis are negatively affected by drought stress, especially at the seedling stage. Understanding the molecular mechanism of A. chinensis drought stress response plays an important role in ensuring medicinal plant production and quality. In this study, A. chinensis seedlings were subjected to drought stress treatment for 0 (control), 3 (D3), and 9 days (D9). For the control, the sample was watered every two days and collected on the second morning after watering. The integration of physiological and transcriptomic analyses was carried out to investigate the effects of drought stress on A. chinensis seedlings and to reveal the molecular mechanism of its drought stress response.

RESULTS

The malondialdehyde, proline, soluble sugar, and crude protein contents and antioxidative enzyme (superoxide dismutase, peroxidase, and catalase) activity were significantly increased under drought stress compared with the control. Transcriptomic analysis indicated a total of 215,665 unigenes with an average length of 759.09 bp and an N50 of 1140 bp. A total of 29,449 differentially expressed genes (DEGs) were detected between the control and D3, and 14,538 DEGs were detected between the control and D9. Under drought stress, terpenoid backbone biosynthesis had the highest number of unigenes in the metabolism of terpenoids and polyketides. To identify candidate genes involved in the sesquiterpenoid and triterpenoid biosynthetic pathways, we observed 22 unigene-encoding enzymes in the terpenoid backbone biosynthetic pathway and 15 unigene-encoding enzymes in the sesquiterpenoid and triterpenoid biosynthetic pathways under drought stress.

CONCLUSION

Our study provides transcriptome profiles and candidate genes involved in sesquiterpenoid and triterpenoid biosynthesis in A. chinensis in response to drought stress. Our results improve our understanding of how drought stress might affect sesquiterpenoid and triterpenoid biosynthetic pathways in A. chinensis.

Effects of Exogenous Abscisic Acid on the Physiological and Biochemical Responses of Camellia oleifera Seedlings under Drought Stress

This study comprehensively investigates the physiological and molecular regulatory mechanisms of Camellia oleifera seedlings under drought stress with a soil moisture content of about 30%, where exogenous abscisic acid (ABA) was applied via foliar spraying at concentrations of 50 µg/L, 100 µg/L, and 200 µg/L. The results demonstrated that appropriate concentrations of ABA treatment can regulate the physiological state of the seedlings through multiple pathways, including photosynthesis, oxidative stress response, and osmotic balance, thereby aiding in the restructuring of their drought response strategy. ABA treatment effectively activated the antioxidant system by reducing stomatal conductance and moderately inhibiting the photosynthetic rate, thus alleviating oxidative damage caused by drought stress. Additionally, ABA treatment promoted the synthesis of osmotic regulators such as proline, maintaining cellular turgor stability and enhancing the plant's drought adaptability. The real-time quantitative PCR results of related genes indicated that ABA treatment enhanced the plant's response to the ABA signaling pathway and improved disease resistance by regulating the expression of related genes, while also enhancing membrane lipid stability. A comprehensive evaluation using a membership function approach suggested that 50 µg/L ABA treatment may be the most-effective in mitigating drought effects in practical applications, followed by 100 µg/L ABA. The application of 50 µg/L ABA for 7 h induced significant changes in various biochemical parameters, compared to a foliar water spray. Notably, superoxide dismutase activity increased by 17.94%, peroxidase activity by 30.27%, glutathione content by 12.41%, and proline levels by 25.76%. The content of soluble sugars and soluble proteins rose by 14.79% and 87.95%, respectively. Additionally, there was a significant decrease of 31.15% in the malondialdehyde levels.

Integrative analysis of transcriptome and metabolome reveals the sesquiterpenoids and polyacetylenes biosynthesis regulation in Atractylodes lancea (Thunb.) DC

Atractylodes lancea (Thunb.) is a perennial medicinal herb, with its dry rhizomes are rich in various sesquiterpenoids and polyacetylenes components (including atractylodin, atractylon and β-eudesmol). However, the contents of these compounds are various and germplasms specific, and the mechanisms of biosynthesis in A. lancea are still unknown. In this study, we identified the differentially expressed candidate genes and metabolites involved in the biosynthesis of sesquiterpenoids and polyacetylenes, and speculated the anabolic pathways of these pharmaceutical components by transcriptome and metabolomic analysis. In the sesquiterpenoids biosynthesis, a total of 28 differentially expressed genes (DEGs) and 6 differentially expressed metabolites (DEMs) were identified. The beta-Selinene is likely to play a role in the synthesis of atractylon and β-eudesmol. Additionally, the polyacetylenes biosynthesis showed the presence of 3 DEGs and 4 DEMs. Notably, some fatty acid desaturase (FAB2 and FAD2) significantly down-regulated in polyacetylenes biosynthesis. The gamma-Linolenic acid is likely involved in the biosynthesis of polyacetylenes and thus further synthesis of atractylodin. Overall, these studies have investigated the biosynthetic pathways of atractylodin, atractylon and β-eudesmol in A. lancea for the first time, and present potential new anchor points for further exploration of sesquiterpenoids and polyacetylenes compound biosynthesis pathways in A. lancea.

Comparative analysis of the rhizosphere microbiome and medicinally active ingredients of Atractylodes lancea from different geographical origins

This study aimed to explore the important role of the rhizosphere microbiome in the quality of Atractylodes lancea (Thunb.) DC. (A. lancea). The rhizosphere microbial community of A. lancea at two sampling sites was studied using metagenomic technology. The results of α-diversity analysis showed that the rhizosphere microbial richness and diversity were higher in the Maoshan area. The higher abundance of core microorganisms of the rhizosphere, especially Penicillium and Streptomyces, in the Maoshan area compared with those in the Yingshan area might be an important factor affecting the yield of A. lancea. Redundancy analysis illustrated that the available phosphorus had a significant effect on the rhizosphere microbial community structure of A. lancea. We also showed that the plant-microbe and microbe-microbe interactions were closer in the Maoshan area than in the Yingshan area, and Streptomyces were the main contributors to the potential functional difference between the two regions. A. lancea in the Maoshan area had a high content of atractylodin and atractylon, which might be related to the enhanced abundance of Streptomyces, Candidatus-Solibacter, and Frankia. Taken together, this study provided theoretical insights into the interaction between medicinal plants and the rhizosphere microbiome and provides a valuable reference for studying beneficial microbes of A. lancea.

The phenotypic variation mechanisms of Atractylodes lancea post-cultivation revealed by conjoint analysis of rhizomic transcriptome and metabolome

The wild Atractylodes lancea rhizomes have been traditionally used as herbal medicine. As the increasingly exhaustion of wild A. lancea, the artificial cultivation mainly contributed to the medicinal material production. However, besides the phenotypic variation of rhizome phenotypic trait alteration, the qualities of cultivated A. lancea decrease compared with the wild counterpart. To unveil the physiological and molecular mechanism beneath the phenotypic variation, GC-MS-based volatile organic compounds (VOCs) profiling and RNAseq-based transcriptome analysis were conducted. The volatile metabolomics profiling revealed 65 differentially accumulated metabolites (DAMs) while the transcriptomic profiling identified 12 009 differentially expressed unigenes (DEGs) post-cultivation. The volatile active compounds including atractylone, and eudesmol accumulated more in wild rhizome than in the cultivated counterpart, and several unigenes in terpene synthesis were downregulated under cultivated condition. Compared with the wild A. lancea rhizome, the contents of bioactive Jasmonic Acid (JAs) in cultivated A. lancea rhizome were higher, and evidences that JAs negatively regulate the terpenes biosynthesis in the cultivated A. lancea rhizome were also provided. The combinational omics analysis further indicated the high correlation between the ten cultivation-suppressed VOCs and the cultivation-altered genes for sesquiterpenoids biosynthesis in A. lancea. The network of the cultivation-altered transcription factors (TFs) and the ten VOCs suggested TFs (e.g. Arabidopsis ERF13 homologs and WRKY50) are involved in the regulation of terpenes biosynthesis. These results laid a theoretical basis for developing geo-herbalism medicinal plants with "high quality and optimal shape".

Authenticating the geographic origins of Atractylodes lancea rhizome chemotypes in China through metabolite marker identification

Introduction

Atractylodes lancea is widely distributed in East Asia, ranging from Amur to south-central China. The rhizome of A. lancea is commonly used in traditional Chinese medicine, however, the quality of products varies across different regions with different geochemical characteristics.

Method

This study aimed to identify the chemotypes of A. lancea from different areas and screen for chemical markers by quantifying volatile organic compounds (VOCs) using a targeted metabolomics approach based on GC-MS/MS.

Results

The A. lancea distributed in Hubei, Anhui, Shaanxi, and a region west of Henan province was classified as the Hubei Chemotype (HBA). HBA is characterized by high content of β-eudesmol and hinesol with lower levels of atractylodin and atractylon. In contrast, the Maoshan Chemotype (MA) from Jiangsu, Shandong, Shanxi, Hebei, Inner Mongolia, and other northern regions, exhibited high levels of atractylodin and atractylon. A total of 15 categories of VOCs metabolites were detected and identified, revealing significant differences in the profiles of terpenoid, heterocyclic compound, ester, and ketone among different areas. Multivariate statistics indicated that 6 compounds and 455 metabolites could serve as candidate markers for differentiating A. lancea obtained from the southern, northern, and Maoshan areas.

Discussion

This comprehensive analysis provides a chemical fingerprint of selected A. lancea. Our results highlight the potential of metabolite profiling combined with chemometrics for authenticating the geographical origin of A. lancea.

Selection of Soybean and Cowpea Cultivars with Superior Performance under Drought Using Growth and Biochemical Aspects

Identifying cultivars of leguminous crops exhibiting drought resistance has become crucial in addressing water scarcity issues. This investigative study aimed to select soybean and cowpea cultivars with enhanced potential to grow under water restriction during the vegetative stage. Two parallel trials were conducted using seven soybean (AS3810IPRO, M8644IPRO, TMG1180RR, NS 8338IPRO, BMX81I81IPRO, M8808IPRO, and BÔNUS8579IPRO) and cowpea cultivars (Aracê, Novaera, Pajeú, Pitiúba, Tumucumaque, TVU, and Xique-xique) under four water levels (75, 60, 45, and 30% field capacity-FC) over 21 days. Growth, water content, membrane damage, photosynthetic pigments, organic compounds, and proline levels were analyzed. Drought stress significantly impacted the growth of both crops, particularly at 45 and 30% FC for soybean and 60 and 45% FC for cowpea plants. The BÔNUS8579IPRO and TMG1180RR soybean cultivars demonstrated the highest performance under drought, a response attributed to increased amino acids and proline contents, which likely help to mitigate membrane damage. For cowpea, the superior performance of the drought-stressed Xique-xique cultivar was associated with the maintenance of water content and elevated photosynthetic pigments, which contributed to the preservation of the photosynthetic efficiency and carbohydrate levels. Our findings clearly indicate promising leguminous cultivars that grow under water restriction, serving as viable alternatives for cultivating in water-limited environments.

Drought stress amelioration in tomato (Solanum lycopersicum L.) seedlings by biostimulant as regenerative agent

Drought adversely affects many physiological and biochemical events of crops. This research was conducted to investigate the possible effects of biostimulants containing plant growth-promoting rhizobacteria (PGPR) on plant growth parameters, chlorophyll content, membrane permeability (MP), leaf relative water content (LRWC), hydrogen peroxide (H2O2), proline, malondialdehyde (MDA), hormone content, and antioxidant enzymes (catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD)) activity of tomato (Solanum lycopersicum L.) seedlings under different irrigation levels. This study was carried out under controlled greenhouse conditions with two irrigation levels (D0: 100% of field capacity and D1: 50% of field capacity) and three biostimulant doses (B0: 0, B1: 4 L ha-1, and B2: 6 L ha-1). The results of the study show that drought stress negatively influenced the growth and physiological characteristics of tomato seedlings while biostimulant applications ameliorated these parameters. Water deficit conditions (50% of field capacity) caused decrease in indole acetic acid (IAA), gibberellic acid (GA), salicylic acid (SA), cytokine, zeatin, and jasmonic acid content of tomato seedlings by ratios of 83%, 93%, 82%, 89%, 50%, and 57%, respectively, and shoot fresh weight, root fresh weight, shoot dry weight, root dry weight, plant height, stem diameter, and leaf area decreased by 43%, 19%, 39%, 29%, 20%, 18%, and 50%, respectively, compared to the control (B0D0). In addition, 21%, 16%, 21%, and 17% reductions occurred in LRWC, chlorophyll a, chlorophyll b, and total chlorophyll contents with drought compared to the control, respectively. Biostimulant applications restored the plant growth, and the most effective dose was 4 L ha-1 under drought condition. Amendment of biostimulant into the soil also enhanced organic matter and the total N, P, Ca, and Cu content of the experiment soil. In conclusion, 4 L ha-1 biostimulant amendment might be a promising approach to mitigate the adverse effects of drought stress on tomato.

Impacts of Deficit Irrigation on Photosynthetic Performance, Productivity and Nutritional Quality of Aeroponically Grown Tuscan Kale (Brassica oleracea L.) in a Tropical Greenhouse

Tuscan kale was grown aeroponically with 5, 30 and 60 min nutrient spraying intervals (defined as 5 minNSIs, 30 minNSIs and 60 minNSIs). Four weeks after transplanting, some 5 minNSI plants were transferred to a 60 minNSI (5 minNSI → 60 minNSI) and 90 minNSI (5 minNSI → 90 minNSI) for one more week. Significantly lower light-saturated rates of photosynthesis and stomatal conductance were observed for plants grown with a 60 minNSI than with a 5 minNSI. However, all plants had similar internal CO₂ concentrations and transpiration rates. Reduced light use efficiency but increased energy dissipation was observed in plants grown in a 60 minNSI. A higher nitrate concentration was observed in 60 minNSI plants compared to 5 minNSI and 30 minNSI plants, while all plants had similar concentrations of total reduced nitrogen, leaf soluble protein and Rubisco protein. Plants grown with prolonged NSIs (deficit irrigation) had lower biomass accumulation due to the inhibition of leaf initiation and expansion compared to 5 minNSIs. However, there was no substantial yield penalty in 5 minNSI → 60 minNSI plants. Enhancements in nutritional quality through deficit irrigation at pre-harvest were measured by proline and total soluble sugar. In conclusion, it is better to grow Tuscan kale with a 5 minNSI for four weeks followed by one week with a 60 minNSI before harvest to reduce water usage, yield penalty and enhance nutritional quality.

Effects of soil drought and nitrogen deposition on BVOC emissions and their O3 and SOA formation for Pinus thunbergii

Soil drought and nitrogen (N) deposition can influence the biogenic volatile organic compound (BVOC) emissions and thereby their ozone (O₃) and secondary organic aerosol (SOA) formation. This study addressed their single and combined effects on BVOC emissions of Pinus thunbergii by laboratory simulation experiments. The results showed that light drought (LD, 50% soil volumetric water content (VWC)) stimulated isoprene, monoterpene, sesquiterpene, and total BVOC emissions, while moderate drought (MD, 30% and 40% VWC) and severe drought (SD, 10% and 20% VWC) inhibited their emissions (except for sesquiterpene in 20% VWC). N deposition decreased other VOC emissions and increased isoprene and sesquiterpene emissions. Total BVOCs and monoterpene were stimulated in low N deposition (LN, 2 g N/(m²·yr)) and inhibited in moderate (MN, 5 g N/(m²·yr)) and high N deposition (HN, 10 g N/(m²·yr)). Under combined treatment of soil drought and N deposition, total BVOC, monoterpene, and other VOC emissions were inhibited, sesquiterpene had no significant change, and isoprene emission was inhibited in MD combined treatment but promoted in SD. The O₃ formation potential (OFP) and SOA formation potential (SOAP) from the changed BVOC emissions were calculated, OFP and SOAP of BVOC emissions and their compositions varied significantly among the treatments. Our study provided theoretical basis for assessing the impact of climate change and atmospheric pollution on BVOC emissions and their contribution to the formation of secondary atmospheric pollution.

Mild shading promotes sesquiterpenoid synthesis and accumulation in Atractylodes lancea by regulating photosynthesis and phytohormones

Atractylodes lancea rhizome (AR) has high medicinal and economic value. A previous study has reported that the accumulation of sesquiterpenoids in AR has obvious advantages under bamboo canopy. A concrete shade value to promote the cultivation of high-quality AR has not been established. In this study, 80% shading was screened at six different light intensities (100%, 80%, 60%, 40%, 20%, 7%), and the mechanism was explored in terms of photosynthetic efficiency and phytohormones levels. The results indicated that the total sesquiterpenoid content of 80% mild shading increased by 58%, 52%, and 35%, respectively, compared to 100% strong light in seedling, expansion, and harvest stages and increased by 144%, 178%, and 94%, respectively, compared with 7% low light. The sesquiterpenoids hinesol and β-eudesmol contributed approximately 70% to the differential contribution ratio between mild shading and strong light (100%) or between mild shading and low light (7%). Furthermore, HMGR, DXR, and FPPS genes, which regulate sesquiterpenoid synthesis, were significantly upregulated in 80% mild shading. Transpiration rate; the intercellular CO₂ concentration; net photosynthetic rate; and levels of jasmonic acid, abscisic acid, and gibberellin were strongly correlated (r > 0.85) with sesquiterpenoid accumulation. Cis-acting elements responding to light and phytohormones were present within the promoter regions of HMGR, DXR, and FPPS. Therefore, 80% shading promotes the synthesis and accumulation of sesquiterpenoids in AR by regulating photosynthetic efficiency and phytohormone production, thereby promoting transcriptional expression.

Comprehensive resistance evaluation of 15 blueberry cultivars under high soil pH stress based on growth phenotype and physiological traits

High soil pH is one of the main abiotic factors that negatively affects blueberry growth and cultivation. However, no comprehensive evaluation of the high soil pH tolerance of different blueberry cultivars has been conducted. Herein, 16 phenotypic and physiological indices of 15 blueberry cultivars were measured through pot experiments, and the high-pH soil tolerance coefficient (HSTC) was calculated based on these indices to comprehensively evaluate the high-soil-pH tolerance of plants. The results demonstrated that high soil pH stress inhibited blueberry 77.growth, and MDA, soluble sugar (SS), and soluble protein (SP) levels increased in leaves. Moreover, in all cultivars, CAT activity in the antioxidant system was enhanced, whereas SOD activity was reduced, and the relative expression levels of the antioxidant enzyme genes SOD and CAT showed similar changes. In addition, the leaf chlorophyll relative content (SPAD), net photosynthetic rate (P_n), transpiration rate (E), and stomatal conductance (G_s) decreased, while changes in the intercellular CO₂ concentration (C_i) were noted in different cultivars. Finally, according to the comprehensive evaluation value D obtained from the combination of principal component analysis (PCA) and membership function (MF), the 15 blueberry cultivars can be divided into 4 categories: high soil pH-tolerant type ['Briteblue' (highest D value 0.815)], intermediate tolerance type ('Zhaixuan 9', 'Zhaixuan 7', 'Emerald', 'Primadonna', 'Powderblue' and 'Chandler'), low high soil pH-tolerant type ('Brightwell', 'Gardenblue', 'Plolific' and 'Sharpblue') and high soil pH-sensitive type ['Legacy', 'Bluegold', 'Baldwin' and 'Anna' (lowest D value 0.166)]. Stepwise linear regression analysis revealed that plant height, SS, E, leaf length, C_i, SOD, and SPAD could be used to predict and evaluate the high soil pH tolerance of blueberry cultivars.

Improved tolerance of apple plants to drought stress and nitrogen utilization by modulating the rhizosphere microbiome via melatonin and dopamine

This study explored the contributions of melatonin and dopamine to the uptake and utilization of nitrogen and the formation of rhizosphere microbial communities in 'Tianhong 2'/M. hupehensis, with the goal improving plant resistance to drought stress. Drought stress was formed by artificially controlling soil moisture content. And melatonin or dopamine solutions were applied to the soil at regular intervals for experimental treatment. After 60 days of treatment, plant indices were determined and the structure of the rhizosphere microbial community was evaluated using high-throughput sequencing technology. The findings revealed two ways through which melatonin and dopamine alleviate the inhibition of growth and development caused by drought stress by promoting nitrogen uptake and utilization in plants. First, melatonin and dopamine promote the absorption and utilization of nitrogen under drought stress by directly activating nitrogen transporters and nitrogen metabolism-related enzymes in the plant. Second, they promote the absorption of nitrogen by regulating the abundances of specific microbial populations, thereby accelerating the transformation of the soil nitrogen pool to available nitrogen that can be absorbed directly by plant roots and utilized by plants. These findings provide a new framework for understanding how melatonin and dopamine regulate the uptake and utilization of nitrogen in plants and improve their ability to cope with environmental disturbances.

Physiological and transcriptome analyses reveal the photosynthetic response to drought stress in drought-sensitive (Fengjiao) and drought-tolerant (Hanjiao) Zanthoxylum bungeanum cultivars

As an important economical plant, Zanthoxylum bungeanum is widely cultivated in arid and semi-arid areas. The studies associated with photosynthesis under drought stress were widely carried out, but not yet in Z. bungeanum. Here, the photosynthesis of two Z. bungeanum cultivars (FJ, Z. bungeanum cv. "Fengjiao"; HJ, Z. bungeanum cv. "Hanjiao") was analyzed under drought stress using physiological indicators and transcriptome data. Drought decreased stomatal aperture and stomatal conductance (Gsw), reduced transpiration rate (E) and sub-stomatal CO₂ concentration (Ci), and lowered chlorophyll and carotenoid content, which reduced the net photosynthetic rate (Pn) of Z. bungeanum. The higher photosynthetic rate in HJ stemmed from its higher chlorophyll content, larger stomatal aperture and Gsw, and higher Ci. Weighted gene co-expression network analysis (WGCNA) identified several ABA signal transduction genes (PYL4, PYL9, and PYR1), LCH-encoding genes (LHCB4.3), and chlorophyll metabolism genes (CRD1, PORA, and CHLH). Additionally, seven transcription factor genes were identified as important factors regulating photosynthesis under drought conditions. In general, a photosynthetic response model under drought stress was built firstly in Z. bungeanum, and the key genes involved in photosynthesis under drought stress were identified. Therefore, the results in our research provide important information for photosynthesis under drought and provided key clues for future molecular breeding in Z. bungeanum.

The phytochrome-interacting factor DcPIF3 of carrot plays a positive role in drought stress by increasing endogenous ABA level in Arabidopsis

The phytochrome-interacting factor (PIF) subfamily of basic helix-loop-helix (bHLH) transcription factors plays a critical role in plant growth and development. However, there has been no detailed report on the PIFs in carrot. In this study, we present the identification and characterization of DcPIF gene family in carrot (Daucus carota L.). Phylogenetic analysis indicated that PIFs from carrot and other five plant species could be divided into four groups supported by similar gene structure and motif analysis. Expression profiles showed that all DcPIF genes were tissue-specific and could be induced by drought or abscisic acid (ABA) treatment except DcPIF7.1, among which DcPIF3 was the most responsive. The DcPIF3-overexpressed Arabidopsis plants exhibited more tolerance to drought stress, with higher antioxidant capacity and lower malondialdehyde content after drought treatment than wild type plants. Further stress tolerance assays revealed that DcPIF3 plays a positive role in drought stress by increasing endogenous ABA level and promoting the expression of ABA-related genes. Our results can enrich the understanding of DcPIF family genes and lay a foundation for further investigation of DcPIF3 function to defend against drought stress in carrot.

Genome-Wide Analysis of the WRKY Gene Family in Malus domestica and the Role of MdWRKY70L in Response to Drought and Salt Stresses

The WRKY transcription factors are unique regulatory proteins in plants, which are important in the stress responses of plants. In this study, 113 WRKY genes were identified from the apple genome GDDH13 and a comprehensive analysis was performed, including chromosome mapping, and phylogenetic, motif and collinearity analysis. MdWRKYs are expressed in different tissues, such as seeds, flowers, stems and leaves. We analyzed seven WRKY proteins in different groups and found that all of them were localized in the nucleus. Among the 113 MdWRKYs, MdWRKY70L was induced by both drought and salt stresses. Overexpression of it in transgenic tobacco plants conferred enhanced stress tolerance to drought and salt. The malondialdehyde content and relative electrolyte leakage values were lower, while the chlorophyll content was higher in transgenic plants than in the wild-type under stressed conditions. In conclusion, this study identified the WRKY members in the apple genome GDDH13, and revealed the function of MdWRKY70L in the response to drought and salt stresses.

Analysis of Plant-Plant Interactions Reveals the Presence of Potent Antileukemic Compounds

A method to identify anticancer compounds in plants was proposed based on the hypothesis that these compounds are primarily present in plants to provide them with an ecological advantage over neighboring plants and other competitors. According to this view, identifying plants that contain compounds that inhibit or interfere with the development of other plant species may facilitate the discovery of novel anticancer agents. The method was developed and tested using Magnolia grandiflora, Gynoxys verrucosa, Picradeniopsis oppositifolia, and Hedyosmum racemosum, which are plant species known to possess compounds with cytotoxic activities. Plant extracts were screened for growth inhibitory activity, and then a thin-layer chromatography bioautography assay was conducted. This located the major antileukemic compounds 1, 2, 4, and 5 in the extracts. Once the active compounds were located, they were extracted and purified, and their structures were determined. The growth inhibitory activity of the purified compounds showed a significant correlation with their antileukemic activity. The proposed approach is rapid, inexpensive, and can easily be implemented in areas of the world with high biodiversity but with less access to advanced facilities and biological assays.

Gene expression variation of Astragalus adsurgens Pall. through discharge plasma and its activated water

To explore the effects of plasma-activated water (PAW) on gene expression, the combined treatment of PAW and discharge plasma on Astragalus adsurgens Pall seeds were performed, and then the gene expression of seedlings after treatmentwas analyzed at the molecular level. A needle array-plate dielectric-barrier discharge plasma was used to treat Astragalus adsurgens Pall seeds for 1, 2, and 3 h, and PAW was prepared at the same time to cultivate seeds. When the treatment time was 3 h, the survival rate of Plasma + PAW seedlings was only 9.2% of that of the CK. The Astragalus adsurgens Pall seedlings were analyzed using reactive oxygen species (ROS) and RNA-Seq. The ROS content of the seedlings in treatment group was significantly higher than that in the CK after 3 days of culture, that PAW cultivated can cause oxidative stress damage to Astragalus adsurgens Pall. The enzyme activity of the treated plant increased and the metabolic rate was accelerated. It helped to regulate the growth process of plants and improve the yield and quality of crops. This study discussed the gene expression of plasma and PAW induced Astragalus adsurgens Pall at the molecular level, and provided experimental data support for plasma and PAW treatment and selection of Astragalus adsurgens Pall.

Physiological, Biochemical and Transcriptomic Analysis of the Aerial Parts (Leaf-Blade and Petiole) of Asarum sieboldii Responding to Drought Stress

Asarum sieboldii Miq. is a leading economic crop and a traditional medicinal herb in China. Leaf-blade and petiole are the only aerial tissues of A. sieboldii during the vegetative growth, playing a vital role in the accumulation and transportation of biomass energy. They also act as critical indicators of drought in agricultural management, especially for crops having underground stems. During drought, variations in the morphology and gene expression of the leaves and petioles are used to control agricultural irrigation and production. Besides, such stress can also alter the differential gene expression in these tissues. However, little is known about the drought-tolerant character of the aerial parts of A. sieboldii. In this study, we examined the physiological, biochemical and transcriptomic responses to the drought stress in the leaf blades and petioles of A. sieboldii. The molecular mechanism, involving in drought stress response, was elucidated by constructing the cDNA libraries and performing transcriptomic sequencing. Under drought stress, a total of 2912 and 2887 unigenes were differentially expressed in the leaf blade and petiole, respectively. The detection of many transcription factors and functional genes demonstrated that multiple regulatory pathways were involved in drought tolerance. In response to drought, the leaf blade and petiole displayed a general physiological character, a higher SOD and POD activity, a higher MDA content and lower chlorophyll content. Three unigenes encoding POD were up-regulated, which can improve POD activity. Essential oil in petiole was extracted. The relative contents of methyleugenol and safrole in essential oil were increased from 0.01% to 0.05%, and 3.89% to 16.97%, respectively, while myristicin slightly reduced from 24.87% to 21.52%. Additionally, an IGS unigene, involved in eugenol biobiosynthesis, was found up-regulated under drought stress, which was predicated to be responsible for the accumulation of methyleugenol and safrole. Simple sequence repeats (SSRs) were characterized in of A. sieboldii, and a total of 5466 SSRs were identified. Among them, mono-nucleotides were the most abundant repeat units, accounting for 44.09% followed by tri-, tetra-, penta and hexa-nucleotide repeats. Overall, the present work provides a valuable resource for the population genetics studies of A. sieboldii. Besides, it provides much genomic information for the functional dissection of the drought-resistance in A. sieboldii, which will be useful to understand the bio-regulatory mechanisms linked with drought-tolerance to enhance its yield.