Increased Drought Tolerance Research Articles

AmMYB82 promotes flavonoid accumulation and enhances drought tolerance in Astragalus membranaceus

Astragalus membranaceus is a medicinal herb extensively used in China. R2R3-MYB is one of the largest transcription factor families in plants, playing a key role in plant development and environmental stress responses. Although quite a few R2R3-MYB transcription factors from economic plants have been characterized, the biological roles of the R2R3-MYB genes in A. membranaceus remain largely unknown. Here, 123 AmR2R3-MYB members in A. membranaceus were systematically identified and their phylogenetic positions, protein and gene structures, and expression patterns were analyzed. Co-expression network analysis revealed that AmMYB82 was a key gene in regulation of flavonoid synthesis. AmMYB82 was found to localize in the nucleus and activated transcription of AmCHS. In the AmMYB82 overexpressing Arabidopsis thaliana, the content of total flavonoids increased, and the expression levels of six enzyme coding genes for flavonoid synthesis, including AmPAL, AmCHS, AmC4H, AmFLS, AmF3H, and Am4CL, were elevated. Overexpression of AmMYB82 enhanced drought tolerance of Arabidopsis seedlings. Furthermore, overexpression of AmMYB82 in A. membranaceus hairy roots increased flavonoid concentration, transcription of the corresponding enzyme genes, and drought stress tolerance. Building on these findings, we developed a working model for AmMYB82 regulating flavonoid biosynthesis and contributing to the abiotic stress response of A. membranaceus. AmMYB82 directly activated enzyme coding genes in the flavonoid biosynthesis pathway such as AmCHS, promoting flavonoid accumulation and increasing drought tolerance. This research enhanced our knowledge of the biological functions of R2R3-MYB genes and provided candidate genes for the genetic breeding of A. membranaceus.

Endophytic Colonization of Beauveria bassiana Enhances Drought Stress Tolerance in Tomato via "Water Spender" Pathway.

Drought stress is one of the most important climate-related factors affecting crop production. Tomatoes (Solanum lycopersicum L.) are economically important crops which are highly sensitive to drought. The entomopathogenic fungus Beauveria bassiana, a widely used biological insecticide, can form symbiotic relationships with plants via endophytic colonization, increasing plant biomass and the ability to resist biotic stress. Under simulated drought stress conditions, the biomass of tomato seedlings such as plant height, root length, stem diameter, fresh weight, and relative water content, as well as the density and size of stomata in tomato leaves were significantly increased after B. bassiana colonization via root irrigation (p < 0.05). Meanwhile, the physicochemical properties associated with drought resistance such as peroxidase activity and proline content increased significantly (p < 0.05), while malondialdehyde reduced significantly (p < 0.05), and the expression levels of key genes related to stomatal development and drought tolerance pathways increased significantly (p < 0.05). These results indicate that the colonization of B. bassiana enhances the water absorption capacity of tomato seedlings and the rate of transpiration significantly and increases drought tolerance in tomato via the "water spender" pathway, which provides a new strategy for improving crop resistance to drought stress.

Influence of previous drought exposure on the 3D microstructure of the cambium and developing xylem in Eucalyptus clones: An X-ray CT investigation

Summary In plant biology research, X-ray computed tomography (CT) has been demonstrated to be useful for studying the complex tissues of trees qualitatively and quantitatively. The cambium plays a very important role in plant growth and development. However, this tissue is relatively poorly studied due to its complex nature and its localization between layers of xylem and phloem cells. Antecedent environmental conditions may have a substantial impact on plant responses to drought and recovery dynamics. Therefore, this study aimed to investigate the impact of previous drought exposure on the 3D microstructure of two commercial Eucalyptus clones by monitoring the development of the cambium, in the same plant and same area of cambial tissue, during a 4-week trial consisting of well-watered, mild drought, severe drought, and rewatering phases. To track microstructural changes, the plants were imaged weekly with non-destructive X-ray micro-computed tomography (μCT). On the last day of the experiment, X-ray nano-CT was also performed. Our results indicate that trees subjected to earlier well-watered conditions were more affected by the severe drought, compared to those previously exposed to mild drought conditions. Thus, previous exposure to water deficit may provide the benefit of increased drought tolerance during future water deficit. Previous mild drought exposure can facilitate morphological adjustments, which potentially enhances drought tolerance during subsequent drought events.

GA-sensitive Rht13 gene improves root architecture and osmotic stress tolerance in bread wheat

The root architecture, more seminal roots, and Deeper roots help the plants to uptake the resources from the deeper soil layer to ensure better growth. The Gibberellic acid-sensitive (GA-sensitive) Rht genes are well known for increasing drought tolerance in wheat. Much work has been performed on the effect of these genes on the plant agronomic traits and little work has been done on the effect of Rht genes on seminal roots and root architecture. This study was designed to evaluate 200 wheat genotypes under normal and osmotic stress. The genotypes were sown in the solution culture and laid under CRD factorial arrangement with three replications and two factors i.e., genotypes and treatments viz. normal and osmotic stress (20% PEG-6000) applied one week after germination. The data was recorded for the root traits. Results demonstrated that out of 200 genotypes, the GA-sensitive Rht13 gene was amplified in 21 genotypes with a fragment length of 1089 bp. In comparison, the GA-insensitive Rht1 gene was amplified in 24 genotypes with a band size of 228 bp. From 200 wheat genotypes, 122 genotypes produced 5 seminal roots, 4 genotypes 4 seminal roots, and 74 genotypes 3 seminal roots. The genotypes G-3 (EBW11TALL#1/WESTONIA-Rht5//QUAIU#1), G-6 (EBW01TALL#1/SILVERSTAR-Rht13B//ROLF07) and G-8 (EBW01TALL#1/SILVERSTAR-Rht13B//NAVJ07) produced 5 seminal roots and have longer coleoptile (> 4.0 cm), root (> 11.0 cm) and shoot (> 17 cm) under normal and osmotic stress. Furthermore, Ujala 16, Galaxy-13, and Fareed-06 produced 3 seminal roots and have short coleoptile (< 3 cm), root (< 9.0 cm) and shoot (< 10.0 cm). These results showed that the genotypes showing the presence of GA-sensitive Rht genes produced a greater number of seminal roots, increased root/shoot growth, and osmotic stress tolerance compared to the genotypes having GA-insensitive Rht genes. Thus, the Rht13 gene improved the root architecture which will help to uptake the nutrients from deeper soil layers. Utilization of Rht13 in wheat breeding has the potential to improve osmotic stress tolerance in wheat.

FaTEDT1L of Octoploid Cultivated Strawberry Functions as a Transcriptional Activator and Enhances Abiotic Stress Tolerance in Transgenic Arabidopsis.

Plants may encounter abiotic stresses, such as drought, flooding, salinity, and extreme temperatures, thereby negatively affecting their growth, development, and reproduction. In order to enhance their tolerance to such stresses, plants have developed intricate signaling networks that regulate stress-responsive gene expression. For example, Arabidopsis Enhanced Drought Tolerance1/HOMEODOMAIN GLABROUS 11 (AtEDT1/HDG11), one of the transcription factor genes from the group IV of homeodomain-leucine zipper (HD-ZIP) gene family, has been shown to increase drought tolerance in various transgenic plants. However, the underlying molecular mechanisms of enhanced stress tolerance remain unclear. In this study, we identified a homologous gene related to AtEDT1/HDG11, named FaTEDT1L, from the transcriptome sequencing database of cultivated strawberry. Phylogenetic analysis revealed the close relationship of FaTEDT1L with AtEDT1/HDG11, which is one of the group IV members of the HD-ZIP gene family. Yeast one-hybrid analysis showed that FaTEDT1L functions as a transcriptional activator. Transgenic Arabidopsis plants overexpressing FaTEDT1L under the control of the cauliflower mosaic virus (CaMV) 35S promoter exhibited significantly enhanced tolerance to osmotic stress (both drought and salinity) when compared to the wild-type (WT) plants. Under osmotic stress, the average root length was 3.63 ± 0.83 cm, 4.20 ± 1.03 cm, and 4.60 ± 1.14 cm for WT, 35S::FaTEDT1L T2 #3, and 35S:: FaTEDT1L T2 #5, respectively. Substantially increased root length in 35S::FaTEDT1L T2 #3 and 35S::FaTEDT1L T2 #5 was noted when compared to the WT. In addition, the average water loss rates were 64%, 57.1%, and 55.6% for WT, 35S::FaTEDT1L T2 #3, and 35S::FaTEDT1L T2 #5, respectively, after drought treatment, indicating a significant decrease in water loss rate of 35S:: FaTEDT1L T2 #3 and 35S::FaTEDT1L T2 #5 is a critical factor in enhancing plant drought resistance. These findings thus highlight the crucial role of FaTEDT1L in mitigating drought and salt stresses and regulating plant osmotic stress tolerance. Altogether, FaTEDT1L shows its potential usage as a candidate gene for strawberry breeding in improving crop resilience and increasing agricultural productivity under adverse environmental conditions.

Bacterial Volatile Organic Compounds as a Strategy to Increase Drought Tolerance in Maize (Zea mays L.): Influence on Plant Biochemistry.

Maize is highly susceptible to drought, which affects growth and yield. This study investigated how bacterial volatile organic compounds (BVOCs) affect maize drought tolerance. Drought reduced shoot size but increased root length, an adaptation for accessing deeper soil moisture. BVOCs from strain D12 significantly increased root length and shoot growth under drought conditions. Drought also altered root biochemistry, decreasing enzyme activity, and increased osmolyte levels. BVOCs from strains F11 and FS4-14 further increased osmolyte levels but did not protect membranes from oxidative damage, while BVOCs from strains D12 and D7 strains reduced osmolyte levels and cell damage. In shoots, drought increased the levels of osmolytes and oxidative stress markers. BVOCs from FS4-14 had minimal effects on shoot biochemistry. BVOCs from D12 and F11 partially restored metabolic activity but did not reduce cell damage. BVOCs from D7 reduced metabolic activity and cell damage. These results suggest that BVOCs can modulate the biochemical response of maize to drought, with some strains evidencing the potential to enhance drought tolerance.

A novel growth-promoting dark septate endophytic fungus improved drought tolerance in blueberries by modulating phytohormones and non-structural carbohydrates.

Drought is a significant global issue affecting agricultural production, and the utilization of beneficial rhizosphere microorganisms is one of the effective ways to increase the productivity of crops and forest under drought. In this study, we characterized a novel growth-promoting dark septate endophytes (DSE) fungus R16 derived from the blueberry roots. Hyphae or microsclerotia were visible within the epidermal or cortical cells of R16-colonized blueberry roots, which was consistent with the typical characteristics of DSE fungi. Inoculation with R16 promoted the growth of blueberry seedlings and the advantage over the control group was more significant under PEG-induced drought. Comparison of physiological indicators related to drought resistance between the inoculated and control groups was performed on the potted blueberry plants, including the chlorophyll content, net photosynthetic rate, root activities, MDA and H2O2 content, which indicated that R16 colonization mitigated drought injury in blueberry plants. We further analyzed the effects of R16 on phytohormones and non-structural carbohydrates (NSCs) to explore the mechanism of increased drought tolerance by R16 in blueberry seedlings. The results showed that except for the GA content, IAA, ZT and ABA varied significantly between the inoculated and control groups. SPS and S6PDH activities in mature leaves, the key enzymes responsible for sucrose and sorbitol synthesis, respectively, as well as SDH, SuSy, CWINV, HXK and FRK in roots, the key enzymes involved in the NSCs metabolism, showed significant differences between the inoculated and control groups before and after drought treatment. These results suggested that the positive effects of R16 colonization on the drought tolerance of blueberry seedlings are partially attributable to the regulation of phytohormone and sugar metabolism. This study provided valuable information for the research on the interaction between DSE fungi and host plants as well as the application of DSE preparations in agriculture.

Leaf starch degradation by β-amylase ZmBAM8 influences drought tolerance in maize

As a typical C4 plant and important crop worldwide, maize is susceptible to drought. In maize, transitory starch (TS) turnover occurs in the vascular bundle sheath of leaves, differing from that in Arabidopsis (a C3 plant). This process, particularly its role in drought tolerance and the key starch-hydrolyzing enzymes involved, is not fully understood. We discovered that the expression of the β-amylase (BAM) gene ZmBAM8 is highly upregulated in the drought-tolerant inbred line Chang7-2t. Inspired by this finding, we systematically investigated TS degradation in maize lines, including Chang7-2t, Chang7-2, B104, and ZmBAM8 overexpression (OE) and knockout (KO) lines. We found that ZmBAM8 was significantly induced in the vascular bundle sheath by drought, osmotic stress, and abscisic acid. The stress-induced gene expression and chloroplast localization of ZmBAM8 align with the tissue and subcellular sites where TS turnover occurs. The recombinant ZmBAM8 was capable of effectively hydrolyzing leaf starch. Under drought conditions, the leaf starch in ZmBAM8-OE plants substantially decreased under light, while that in ZmBAM8-KO plants did not decrease. Compared with ZmBAM8-KO plants, ZmBAM8-OE plants exhibited increased drought tolerance. Our study provides insights into the significance of leaf starch degradation in C4 crops and contributes to the development of drought-resistant maize.

Identification of Drought Tolerant Chickpea Genotypes under Simulated Drought

Chickpea (Cicer arietinum L.) is one of the most important legume crops worldwide, with high protein content. Chickpea productivity is highly threatened by abiotic stresses, of which drought exerts the most crucial role in terms of growth inhibition and yield losses encountered. Since germination is a critical stage that is negatively affected by drought, an experiment was conducted to estimate the genotypic variability among 27 chickpea genotypes and to determine the seed germination and seedling growth ability under water stress conditions. Seeds were subjected to water stress by using polyethylene glycol (PEG-6000) at five stress levels (0, 5, 10, 15 and 20 % PEG). Among the genotype DIBG 205 (94.50%) recorded highest germination percentage compared to other genotypes. Root length recorded was highest in ICCV 4958 (18.48 cm) under 10% PEG -6000 and decreased with increase in osmotic stress. Drought significantly affected germination as well as all other associated traits with the effects of stress being analogous to the stress level applied. Seedling vigour index is a suitable selection criterion for drought tolerance, high seedling vigour index was observed in DIBG 205 and ICCV 4958 showing increased drought tolerance at high stress level, whereas low seedling vigour index was recorded in ICCV 201217 and ICCV 201116 indicating their possible exploitation as valuable genetic material for further breeding programs for drought tolerance.

Comprehensive analysis of drought tolerance in pure lines derived from half-diallel crosses of upland cotton (Gossypium hirsutum L.)

Drought has a significant impact on plants, affecting their growth, development and survival. This study focuses on evaluating the impact of drought stress, a significant abiotic factor, on the agronomic and fiber parameters of potential cotton (Gossypium hirsutum L.) lines with the aim of developing drought-tolerant varieties. The experiment involved two irrigation regimes—well-watered (100% field capacity) and deficit irrigation (50% field capacity)—conducted on F9–F10 generations. Key fiber parameters, including fiber length, boll weight, fiber strength, and lint percentage, were identified as crucial selection criteria under both well-watered and deficit irrigation conditions. Notably, boll number emerged as the decisive parameter in both F9 and F10 generations. The study employed univariate and multivariate analyses, such as PCA, heat map cluster, correlation analysis, and decision tree, which consistently highlighted fiber length, boll weight, fiber strength and lint (ginning) percentage the key factor. In the F10 generation, the integration of decision tree and heat map cluster results led to the identification of 8 promising lines. These selected genotypes have potential for inclusion in future cotton breeding programmes, offering the opportunity to increase drought tolerance and improve cotton yield and productivity. Their resilience to environmental stresses makes them promising candidates for improving overall cotton performance under challenging conditions.

Synthetic cultivar development in cumin: Enhancing yield and drought tolerance

Cumin (Cuminum cyminum L.) is a valuable spice crop with medicinal properties belonging to the Apiaceae family. While farmers often favor the cultivation of cumin, low seed yield, particularly under drought stress, poses challenges to its commercial production. Due to cumin small flowers, self-incompatibility, and cross-pollination attributes, the production of synthetic varieties through polycross breeding can be an effective method for improving seed performance and enhancing drought tolerance in cumin. This study, for the first time, investigates the breeding progress of cumin in three populations over two generations. The first generation resulting from polycross breeding (SYN2 population), along with parental genotypes, was evaluated for agro-morphological traits under normal and low-water irrigation conditions in two locations and compared with the SYN1 population. Additionally, genetic diversity among parental genotypes, SYN1, and SYN2 populations was examined using Start Codon Targeted Polymorphism (SCoT) markers. Low water stress negatively affected all studied traits, except for essential oil content. Improved seed yield, increased drought tolerance, and higher cuminaldehyde content were observed in the SYN2 population compared to parental genotypes. Estimation of genetic parameters indicated a higher heritability and heterosis for traits in the SYN1 population compared to SYN2. Furthermore, trait heritability in the SYN2 population was higher under normal irrigation condition than under water stress. The highest narrow-sense heritability in both SYN1 and SYN2 populations was associated with the thousand-seed weight. Positive and significant phenotypic and genotypic correlations between thousand-seed weight and seed yield were observed in the SYN1 population, while the SYN2 population exhibited the least negative impact of drought stress on this trait. Grouping populations through cluster analysis and principal coordinate analysis based on both molecular and agro-morphological data showed complete concordance, effectively distinguishing cumin populations from one another. The SCoT molecular marker confirmed the homogeneity of the improved populations, demonstrating high efficiency in assessing intra- and inter-population diversity. Molecular variance analysis revealed lower within-population diversity (29 %) compared to between-population diversity (71 %). Among populations, SYN1, equivalent to F2 generation, exhibited the highest level of molecular diversity based on diversity indices.

A Perennial Green Revolution to address 21st‐century food insecurity and malnutrition

AbstractFarming practices of the past century have dramatically increased annual crop yields to unprecedented levels but have consequentially created increasing ecological and public health concerns, posing a long‐term threat to global food security. Soil tillage and chemical inputs perpetuate soil erosion, biodiversity loss, wetlands eutrophication, carbon emissions, and other farming stressors. Concomitantly, accompanying poor dietary patterns and malnutrition increase the risk for chronic diseases, such as cardiovascular diseases, obesity, type 2 diabetes, and cancer, which account for greater than 70% of global mortality per annum. Altogether, such annual monocropping systems exacerbate food insecurity, necessitating action across the fields of public health, agriculture, nutrition, medicine, and environmental ecology, that is, a transdisciplinary approach. Herein, we argue that the perennialization of crops creates an opportunity to address the challenges of environmental sustainability and nutritional adequacy economically. Unlike annuals, perennial crops have deeper roots for increased drought tolerance and reduced needs for fertilization and irrigation. Adopting perenniality can result in greater drought tolerance and improved soil health while reducing erosion, farming labor, and seed purchasing. Furthermore, perennializing novel staple crops may offer a superior and diverse dietary profile of phytochemicals, fiber, and macronutrients compared to conventional annuals. Instead of traditional perennial tree crops, we focus on intermediate wheatgrass Kernza® (Thinopyrum intermedium) and sunflowers (Helianthus tuberosus, H. maximiliani, and Silphium integrifolium) as exemplars of perennial staple food crops for grain and oil, respectively, at different stages of perennial crop commercialization. Ultimately, we discuss how integrating perenniality has the potential to revolutionize global agriculture and address food security concerns for the remainder of the 21st century.

BcSRC2 interacts with BcAPX4 to increase ascorbic acid content for responding ABA signaling and drought stress in pak choi

Abstract As a reducing substance, ascorbic acid functioned well in abiotic and biotic stress. However, the regulatory mechanism of drought resistance is rarely known in pak choi. Here we found a gene BcSRC2 containing a C2 domain that responds to ABA signal and drought regulation in pak choi. Silencing of BcSRC2 reduces ascorbic acid content and drought resistance of pak choi. In Arabidopsis, BcSRC2 overexpression promotes ascorbic acid accumulation and increases drought tolerance. Meanwhile, transcriptome analysis between WT and BcSRC2-overexpressing pak choi suggests that ascorbic acid-related genes are regulated. BcSRC2 interacts with BcAPX4 and inhibit APX activity in vitro and in vivo, increasing the ascorbic acid content. We also found that drought stress increases ABA content, which reduces the expression of BcMYB30. BcMYB30 bound to the promoter of BcSRC2 and reduced its expression. Overall, our results suggest that a regulatory module, BcMYB30-BcSRC2-BcAPX4, plays a central role in increasing ascorbic acid content for responding ABA-mediated drought regulation in pak choi.

Enhancing plant resilience: arbuscular mycorrhizal fungi's role in alleviating drought stress in vegetation concrete.

Drought stress usually inhibits plant growth, which may increase the difficulty of greening slopes. In this study, we systematically investigated the effects of arbuscular mycorrhizal (AM) fungi on the growth and drought tolerance of two plant species, Festuca elata and Cassia glauca, in a vegetation concrete environment by exogenously inoculating AM fungi and setting three drought levels: well water, moderate drought and severe drought. The results showed that plant growth was significantly inhibited under drought stress; however, AM fungi inoculation significantly promoted plant height, root length, and above- and belowground biomass in these two plant species. Compared with, those in the CK treatment, the greatest increases in the net photosynthesis rate, stomatal conductance and transpiration rate in the AM treatment group were 36.72%, 210.08%, and 66.41%, respectively. Moreover, inoculation with AM fungi increased plant superoxide dismutase and catalase activities by 4.70-150.73% and 9.10-95.70%, respectively, and reduced leaf malondialdehyde content by 2.79-55.01%, which alleviated the damage caused by oxidative stress. These effects alleviated the damage caused by oxidative stress and increased the content of soluble sugars and soluble proteins in plant leaves by 1.52-65.44% and 4.67-97.54%, respectively, which further increased the drought adaptability of plants. However, inoculation with AM fungi had different effects on different plants. In summary, this study demonstrated that the inoculation of AM fungi in vegetation concrete environments can significantly increase plant growth and drought tolerance. The plants that formed a symbiotic structure with AM fungi had a larger root uptake area, greater water uptake capacity, and greater photosynthesis and gas exchange efficiency. In addition, AM fungi inoculation further increased the drought adaptability of the plants by increasing their antioxidant enzyme activity and regulating their metabolite content. These findings are highly important for promoting plant growth and increasing drought tolerance under drought conditions, especially for potential practical applications in areas such as slope protection, and provide useful references for future ecological engineering and sustainable development.

Associative Bacteria and Arbuscular Mycorrhizal Fungus Increase Drought Tolerance in Maize (Zea mays L.) through Morphoanatomical, Physiological, and Biochemical Changes.

Water deficiency has been recognized as a major abiotic stress that causes losses in maize crops around the world. The maize crop is very important due to the range of products that are derived from this plant. A potential way to reduce the damages caused by water deficiency in maize crops is through the association with plant growth-promoting bacteria (PGPB) and arbuscular mycorrhizal fungi (AMF). To define the mechanisms developed by associative PGPB and AMF in maize that are involved in protection against moderate drought (MD), this study evaluated the biometrical, anatomical, biochemical, and physiological parameters of maize grown under MD and inoculated with different PGPB (Azospirillum brasilense strain Ab-V5 and Bacillus sp. strain ZK) and with AMF. The relative water content did not change in the treatments. The association with ZK increased the shoot:total ratio, total dry weight, maximum quantum yield of photosystem II, vascular cylinder thickness, and vascular cylinder area. The Ab-V5 inoculation led to an increment in root dry weight, the area of metaxylem vessel elements, and nitrate reductase activity. The AMF association did not lead to changes in the measured parameters. The results indicate that the association with PGPB is a relevant alternative to contribute to reducing losses in maize crops under drought. However, AMF is not indicated for this crop under drought.

Characterization of DREB family genes in Lotus japonicus and LjDREB2B overexpression increased drought tolerance in transgenic Arabidopsis

BackgroundDrought stress affects plant growth and development. DREB proteins play important roles in modulating plant growth, development, and stress responses, particularly under drought stress. To study the function of DREB transcription factors (TFs), we screened key DREB-regulating TFs for drought in Lotus japonicus.ResultsForty-two DREB TFs were identified, and phylogenetic analysis of proteins from L. japonicus classified them into five subfamilies (A1, A2, A4, A5, A6). The gene motif composition of the proteins is conserved within the same subfamily. Based on the cis-acting regulatory element analysis, we identified many growth-, hormone-, and stress-responsive elements within the promoter regions of DREB. We further analyzed the expression pattern of four genes in the A2 subfamily in response to drought stress. We found that the expression of most of the LjDREB A2 subfamily genes, especially LjDREB2B, was induced by drought stress. We further generated LjDREB2B overexpression transgenic Arabidopsis plants. Under drought stress, the growth of wild-type (WT) and overexpressing LjDREB2B (OE) Arabidopsis lines was inhibited; however, OE plants showed better growth. The malondialdehyde content of LjDREB2B overexpressing lines was lower than that of the WT plants, whereas the proline content and antioxidant enzyme activities in the OE lines were significantly higher than those in the WT plants. Furthermore, after drought stress, the expression levels of AtP5CS1, AtP5CS2, AtRD29A, and AtRD29B in the OE lines were significantly higher than those in the WT plants.ConclusionsOur results facilitate further functional analysis of L. japonicus DREB. LjDREB2B overexpression improves drought tolerance in transgenic Arabidopsis. These results indicate that DREB holds great potential for the genetic improvement of drought tolerance in L. japonicus.

Market Potential for Specialty Compost Produced from Wool Waste

In several regions of the United States, waste and “tag” wool are readily available, inexpensive, and considered low-quality because of weed seed contamination and stains from defecation. Because of an overabundance of waste and tag wool, some are landfilled. Previous research has indicated that wool or hair incorporated in potted plants can improve the water-holding capacity of the soil and act as a slow-release fertilizer. Furthermore, compost trials have demonstrated that wool produces a high-quality compost product. This study aimed to evaluate the market potential of wool-based compost to determine its commercial viability. To address this, we conducted in-depth interviews with lead user gardeners (n = 10) who used 1 yard of wool-based compost in their gardens over the course of 10 weeks and distributed a quantitative survey instrument to both lead users and general gardeners recruited from garden centers, nurseries, and horticulture classes (n = 256). Lead users responded positively to the wool-based compost and reported they would be willing to pay $6 to $7 per ft3. General gardeners who were less familiar with the product reported they were willing to pay at least a similar amount as that for typical market composts, but they suggested that they would pay more if characteristics such as “increases drought tolerance” were used in advertising. Our analysis indicated that the target audience for the wool-based compost is male gardeners older than 25 years who are concerned about the environment.

Exogenous application of 5-NGS increased osmotic stress resistance by improving leaf photosynthetic physiology and antioxidant capacity in maize.

Drought is a critical limiting factor affecting the growth and development of spring maize (Zea mays L.) seedlings in northeastern China. Sodium 5-nitroguaiacol (5-NGS) has been found to enhance plant cell metabolism and promote seedling growth, which may increase drought tolerance. In the present study, we investigated the response of maize seedlings to foliar application of a 5-NGS solution under osmotic stress induced by polyethylene glycol (PEG-6000). Four treatment groups were established: foliar application of distilled water (CK), foliar application of 5-NGS (NS), osmotic stress + foliar application of distilled water (D), and osmotic stress + foliar application of 5-NGS (DN). Plant characteristics including growth and photosynthetic and antioxidant capacities under the four treatments were evaluated. The results showed that under osmotic stress, the growth of maize seedlings was inhibited, and both the photosynthetic and antioxidant capacities were weakened. Additionally, there were significant increases in the proline and soluble sugar contents and a decrease in seedling relative water content (RWC). However, applying 5-NGS alleviated the impact of osmotic stress on maize seedling growth parameters, particularly the belowground biomass, with a dry mass change of less than 5% and increased relative water content (RWC). Moreover, treatment with 5-NGS mitigated the inhibition of photosynthesis caused by osmotic stress by restoring the net photosynthetic rate (Pn) through an increase in chlorophyll content, photosynthetic electron transport, and intercellular CO2 concentration (Ci). Furthermore, the activity of antioxidant enzymes in the aboveground parts recovered, resulting in an approximately 25% decrease in both malondialdehyde (MDA) and H2O2. Remarkably, the activity of enzymes in the underground parts exhibited more significant changes, with the contents of MDA and H2O2 decreasing by more than 50%. Finally, 5-NGS stimulated the dual roles of soluble sugars as osmoprotectants and energy sources for metabolism under osmotic stress, and the proline content increased by more than 30%. We found that 5-NGS played a role in the accumulation of photosynthates and the effective distribution of resources in maize seedlings. Based on these results, we determined that foliar application of 5-NGS may improve osmotic stress tolerance in maize seedlings. This study serves as a valuable reference for increasing maize yield under drought conditions.

Hydrogen Sulfide Increases Drought Tolerance by Modulating Carbon and Nitrogen Metabolism in Foxtail Millet Seedlings

Hydrogen sulfide (H2S), a novel gas signaling molecule, has been shown to enhance plant resistance to various abiotic stresses. Here, we investigated the effect of sodium hydrosulfide (NaHS, a H2S donor) on the growth, photosynthetic parameters, and enzyme activities related to carbon and nitrogen metabolism, as well as the levels of carbohydrates and nitrogen metabolites in foxtail millet seedlings subjected to drought stress conditions in pots. The findings revealed that drought stress led to a significant 41.2% decline in the total dry weight (DW) after 12 days of treatment, whereas plants treated with NaHS showed a lesser reduction of 18.7% in total DW. Under drought stress, exogenous NaHS was found to enhance carbon metabolism in foxtail millet seedlings by significantly enhancing photosynthetic capacity, starch, and sucrose content. Additionally, exogenous NaHS was observed to improve nitrogen metabolism by substantially increasing soluble protein content, nitrogen assimilate activity, and synthesis of nitrogen-containing compounds in foxtail millet seedlings. In summary, the exogenous application of NaHS stimulated seedling growth and enhanced drought resistance in foxtail millet by modulating carbon and nitrogen metabolism processes affected by drought stress.

Integrated metabolomic and metagenomic strategies shed light on interactions among planting environments, rhizosphere microbiota, and metabolites of tobacco in Yunnan, China.

Changes in climatic factors and rhizosphere microbiota led plants to adjust their metabolic strategies for survival under adverse environmental conditions. Changes in plant metabolites can mediate crop growth and development and interact with rhizosphere microbiota of the plant rhizosphere. To understand the interactions among environmental factors, rhizosphere microbiota, and metabolites of tobacco, a study was conducted by using integrated metagenomic and metabolomic strategies at four typical representative tobacco planting sites in Yunnan, China. The results showed that the agronomical and biochemical traits were significantly affected by temperature, precipitation (PREP), soil pH, and altitude. Correlation analyses revealed a significant positive correlation of temperature with length, width, and area of the leaf, while PREP correlated with plant height and effective leaf numbers. Furthermore, total sugar and reducing sugar contents of baked leaves were significantly higher, while the total nitrogen and total alkaloid levels were lower in tobacco leaves at site with low PREP. A total of 770 metabolites were detected with the highest number of different abundant metabolites (DMs) at Chuxiong (CX) with low PREP as compared to the other three sites, in which secondary metabolites were more abundant in both leaves and roots of tobacco. A total of 8,479 species, belonging to 2,094 genera with 420 individual bins (including 13 higher-quality bins) harboring 851,209 CDSs were detected. The phyla levels of microorganisms such as Euryarchaeota, Myxococcota, and Deinococcota were significantly enriched at the CX site, while Pseudomonadota was enriched at the high-temperature site with good PREP. The correlation analyses showed that the metabolic compounds in low-PREP site samples were positively correlated with Diaminobutyricimonas, Nissabacter, Alloactinosynnema, and Catellatospora and negatively correlated with Amniculibacterium, Nordella, Noviherbaspirillum, and Limnobacter, suggesting that the recruitment of Diaminobutyricimonas, Nissabacter, Alloactinosynnema, and Catellatospora in the rhizosphere induces the production and accumulation of secondary metabolites (SMs) (e.g., nitrogen compounds, terpenoids, and phenolics) for increasing drought tolerance with an unknown mechanism. The results of this study may promote the production and application of microbial fertilizers and agents such as Diaminobutyricimonas and Alloactinosynnema to assemble synthetic microbiota community or using their gene resources for better cultivation of tobacco as well as other crops in drought environments.