Shoot Research Articles

Genome-wide association study of drought tolerance in wheat (Triticum aestivum L.) identifies SNP markers and candidate genes

Drought stress poses a severe threat to global wheat production, necessitating an in-depth exploration of the genetic basis for drought tolerance associated traits. This study employed a 90 K SNP array to conduct a genome-wide association analysis, unravelling genetic determinants of key traits related to drought tolerance in wheat, namely plant height, root length, and root and shoot dry weight. Using the mixed linear model (MLM) method on 125 wheat accessions subjected to both well-watered and drought stress treatments, we identified 53 SNPs significantly associated with stress susceptibility (SSI) and tolerance indices (STI) for the targeted traits. Notably, chromosomes 2A and 3B stood out with ten and nine associated markers, respectively. Across 17 chromosomes, 44 unique candidate genes were pinpointed, predominantly located on the distal ends of 1A, 1B, 1D, 2A, 3A, 3B, 4A, 6A, 6B, 7A, 7B, and 7D chromosomes. These genes, implicated in diverse functions related to plant growth, development, and stress responses, offer a rich resource for future investigation. A clustering pattern emerged, notably with seven genes associated with SSI for plant height and four genes linked to both STI of plant height and shoot dry weight, converging on specific regions of chromosome arms of 2AS and 3BL. Additionally, shared genes encoding polygalacturonase, auxilin-related protein 1, peptide deformylase, and receptor-like kinase underscored the interconnectedness between plant height and shoot dry weight. In conclusion, our findings provide insights into the molecular mechanisms governing wheat drought tolerance, identifying promising genomic loci for further exploration and crop improvement strategies.Graphical (1) A diverse panel of wheat genotypes was cultivated under both well-watered and drought stress conditions; (2) Phenotyping involved washing, scanning, drying and weighing plants to evaluate the stress susceptibility (SSI) and stress tolerance (STI) indices for four drought tolerance-related traits; (3) Genotyping was performed by extracting DNA and using the wheat 90 K Illumina iSelect array; (4) Phenotypic and genotypic data were utilized in a genome-wide association analysis (GWAS) using a mixed linear model (MLM); (5) Population structure assessment, principal component analysis (PCA), and kinship analysis were conducted; (6) Candidate genes were identified, and (7) their molecular functions were analysed and discussed.

Zinc toxicity and tolerance-related responses in Inga marginata and Allophylus edulis seedlings

Although zinc (Zn) is a micronutrient, excessive amounts in the soil can have toxic effects on plants. Fertilizers, limestone materials, pesticides, and fungicides added with Zn have contributed to increasing the concentration of this element in agricultural soils. Accordingly, it is necessary to find Zn-tolerant plant species to be properly used in degraded soil restoration programs. Thus, the current study aims to investigate the influence of different Zn concentrations on photosynthetic variables, antioxidant activity, and growth of I. marginata and A. edulisseedlings to determine their potential to be used as phytoremediation species. The experiment was installed in a 2×5 factorial scheme, with the first factor being two species (Allophylus edulis and Inga marginata), and the second factor: five concentrations of Zn (2, 75, 150, 225, and 300 μM), with three replications per treatment. Each sampling unit consisted of a pot with five plants. Photosynthetic, morphological variables of the shoot and root systems, chlorophyll a fluorescence, photosynthetic pigments, antioxidant enzyme activity, lipid peroxidation, hydrogen peroxide concentration, and Zn accumulated in the roots and shoot were evaluated. Zn stress has activated an efficient antioxidant system, which reduced oxidative damage in the leaves of both species; consequently, it did not decrease shoot biomass production in Inga marginata and Allophylus edulis seedlings. High Zn accumulation in plant tissues and lack of negative effects on Inga marginata and Allophylus edulis shoot have suggested that these plant species are tolerant to Zn and may be indicated for Zn-polluted soil phytoremediation purposes.

DcERF109 regulates shoot branching by participating in strigolactone signal transduction in Dendrobium catenatum.

Shoot branching fundamentally influences plant architecture and agricultural yield. However, research on shoot branching in Dendrobium catenatum, an endangered medicinal plant in China, remains limited. In this study, we identified a transcription factor DcERF109 as a key player in shoot branching by regulating the expression of strigolactone (SL) receptors DWARF 14 (D14)/ DECREASED APICAL DOMINANCE 2 (DAD2). The treatment of D. catenatum seedlings with GR24rac/TIS108 revealed that SL can significantly repress the shoot branching in D. catenatum. The expression of DcERF109 in multi-branched seedlings is significantly higher than that of single-branched seedlings. Ectopic expression in Arabidopsis thaliana demonstrated that overexpression of DcERF109 resulted in significant shoot branches increasing and dwarfing. Molecular and biochemical assays demonstrated that DcERF109 can directly bind to the promoters of AtD14 and DcDAD2.2 to inhibit their expression, thereby positively regulating shoot branching. Inhibition of DcERF109 by virus-induced gene silencing (VIGS) resulted in decreased shoot branching and improved DcDAD2.2 expression. Moreover, overexpression of DpERF109 in A. thaliana, the homologous gene of DcERF109 in Dendrobium primulinum, showed similar phenotypes to DcERF109 in shoot branch and plant height. Collectively, these findings shed new insights into the regulation of plant shoot branching and provide a theoretical basis for improving the yield of D. catenatum.

Drought induces moderate, diverse changes in the odour of grassland species

Plants react to drought stress with numerous changes including altered emissions of volatile organic compounds (VOC) from leaves, which provide protection against oxidative tissue damage and mediate numerous biotic interactions. Despite the share of grasslands in the terrestrial biosphere, their importance as carbon sinks and their contribution to global biodiversity, little is known about the influence of drought on VOC profiles of grassland species. Using coupled gas chromatography-mass spectrometry, we analysed the odorants emitted by 22 European grassland species exposed to an eight-week-lasting drought treatment (DT; 30% water holding capacity, WHC). We focused on the odorants emitted during the light phase from whole plant shoots in their vegetative stage. Emission rates were standardised to the dry weight of each shoot. Well-watered (WW) plants (70% WHC) served as control. Drought-induced significant changes included an increase in total emission rates of plant VOC in six and a decrease in three species. Diverging effects on the number of emitted VOC (chemical richness) or on the Shannon diversity of the VOC profiles were detected in 13 species. Biosynthetic pathways-targeted analyses revealed 13 species showing drought-induced higher emission rates of VOC from one, two, three, or four major biosynthetic pathways (lipoxygenase, shikimate, mevalonate and methylerythritol phosphate pathway), while six species exhibited reduced emission rates from one or two of these pathways. Similarity trees of odorant profiles and their drought-induced changes based on a biosynthetically informed distance metric did not match species phylogeny. However, a phylogenetic signal was detected for the amount of terpenoids released by the studied species under WW and DT conditions. A comparative analysis of emission rates of single compounds released by WW and DT plants revealed significant VOC profile dissimilarities in four species only. The moderate drought-induced changes in the odorant emissions of grassland species are discussed with respect to their impact on trophic interactions across the food web. (294 words)

Residual hydrocarbons in long-term contaminated soils: implications to risk-based management

Petroleum hydrocarbon (PHC) contamination is a widespread and severe environmental issue affecting many countries’ resource sectors. PHCs are mixtures of hydrocarbon compounds with varying molar masses that naturally attenuate at different rates. Lighter fractions attenuate first, followed by medium-molar-mass constituents, while larger molecules remain for longer periods. This results in significant regulatory challenges concerning residual hydrocarbons in long-term contaminated soils. This study examined the potential risks associated with residual PHC and its implications for risk-based management of heavily contaminated soils (23,000–26,000 mg PHC/kg). Ecotoxicological properties, such as seedling emergence and growth of two native plant species—small Flinders grass (Iseilema membranaceum) and ruby saltbush (Enchylaena tomentosa)—and earthworm survival tests in PHC-contaminated soils, were assessed. Additionally, the effects of aging on the attenuation of PHC in contaminated soils were evaluated. Toxicity responses of plant growth parameters were determined as no-observed-effect concentrations: 75%–100% for seedling emergence, < 25%–75% for plant shoot height, and 75%–100% for earthworm survival. After 42 weeks of aging, the total PHC levels in weathered soils decreased by 14% to 30% and by 67% in diesel-spiked soil due to natural attenuation. Dehydrogenase enzyme activity in soils increased during the initial aging period. Furthermore, a clear shift of bacterial communities was observed in the soils following aging, including enrichment of PHC-resistant and -utilizing bacteria—for example, Nocardia sp. This study underscores the potential of natural attenuation for eco-friendly and cost-effective soil management, underlining that its success depends on site-specific factors like water content and nutrient availability. Therefore, we recommend detailed soil assessments to evaluate these conditions prior to adopting a risk-based management approach.

A biocompatible NPK+Fe+Zn slow release fertilizer: synthesis and its evaluation in tomato plant growth improvement

Slow-release fertilizers (SRFs) play an essential and necessary role in sustainable agriculture. Using slow-release and environment friendly fertilizers can increase the growth of plants and reduce the loss of nutrients. Considering the deficiency of iron (Fe) and zinc (Zn) in calcareous soils, a slow-release fertilizer was prepared based on the polymeric nanocomposite, which contains NPK, Fe, and Zn. Its potential was evaluated on tomato plant growth by conducting an experiment in a factorial completely randomized design with three replications. Two levels of salinity (2 and 5 ds m−1, two types of soil texture) clay loam and sandy loam) and five levels of fertilizers were examined in the experiment. To this, the graphene oxide-chitosan coated-humic acid@Fe3O4 nanoparticles (Fe3O4@HA@GO-Cs), and the graphene oxide-chitosan coated-ammonium zinc phosphate (AZP@GO-Cs) were used as Fe and Zn sources, respectively. Then, the optimal Fe and Zn fertilizers in the presence of urea, phosphorus, and potassium slow- release fertilizers (SRF) were investigated under greenhouse conditions. The results indicated that the best improvement in growth and nutrient uptake in plants was achieved by using the SRF. Notably, in the shoots of tomato plants, the nitrogen, phosphorus, potassium, Fe, and Zn concentration increased by 44, 66, 46, 75, and 74% compared to the control. The use of nanofertilizer can be an effective, biocompatible, and economical option to provide Fe and Zn demand in plants.

Influence of Various Bacterial and Fungal Strains on Fruit Cuttings: A Review

Microbes, especially bacteria and fungi, play a significant role in the plant's multiplication outcome as well as in regulating the success of economic yield. There are some beneficial interactions made by the various fungi and bacteria, such as Pseudomonas aeruginosa, Bacillus subtilis, and endophytic fungi, which may be responsible for plant vigor, growth, shoot and root development. Bacterial and fungal strains engaged in the uptake, utilization and nutrient transportation in the earth's pores influence the distribution of essential vitamins and minerals for plant development. We may conclude that the influence of various bacterial and fungal strains on fruit cuttings is a complex and multifaceted issue. It is clear that advanced research is obligatory to better understand the precise interactions between different strains and fruit cuttings, as well as to develop strategies for managing and justifying the potential negative impacts. By achieving a deeper and clear understanding of these interactions, we can work towards optimizing health and productivity.

Bacterial consortium based on Pseudomonas fluorescens, Lysinibacillus xylanilyticus and Bacillus velezensis reduces clubroot disease in broccoli

Clubroot disease caused by Plasmodiophora brassicae is the most devastating disease in Brassicaceae plants. Control of clubroot is limited because of the survival of resting spores of the pathogen in the soil for years. Crop rotation, liming of the soil, fungicides and resistant cultivars have not been totally efficient in reducing the damages of the disease or pathogen spread. Although biocontrol with microorganisms has shown potential against clubroot, the variable results when using individual strains have made implementation difficult. Thus, the aim of this work was to determine whether a consortium of selected beneficial microorganisms is more efficient in controlling clubroot in broccoli than single strains. Single strains of bacteria from the Lysinibacillus, Bacillus and Pseudomonas genera (5 × 107 cells ml−1) and Trichoderma spp. (1 × 106 conidia ml−1) were evaluated in an initial screening. Four strains showing the best performance on plant growth and reduction of clubroot were evaluated as consortia in a further experiment. Treatments were applied in nursery (4 ml plant−1), and to the soil one week before transplant and the day of transplant (60 ml plant−1 each time). Plant shoot and root dry weight and the incidence and severity of clubroot were recorded. Supernatant from liquid cultures of Pseudomonas migulae Pf014 and Lysinibacillus xylanilyticus Br042, and washed cells of Bacillus velezensis Bs006 and B. pumilus Br019 promoted shoot growth of the plants. Single applications of Trichoderma asperellum Th034, Bs006, Br042 and Pseudomonas fluorescens Ps006 showed biocontrol potential against clubroot. However, the consortia built of Bs006, Br042 and Ps006 showed the highest reduction of clubroot incidence (78%) and severity (74%). A synergistic interaction by this consortium was found compared with the efficacy of single strains. To our knowledge, this work reports for the first time a consortium based on three rhizobacteria with high potential to control clubroot disease.

Growing Salicornia europaea L. with Saline Hydroponic or Aquaculture Wastewater

Among halophyte plants, Salicornia species (also known as glasswort or sea asparagus) are increasingly grown in open fields and greenhouses for edible or non-edible purposes. Their salinity tolerance makes it possible to irrigate Salicornia plants with saline waters and even seawater, which cannot be used by other crop species. In this work, S. europaea (L.) was cultivated in pots under the typical climatic conditions of the fall season in the Mediterranean region and irrigated with non-saline standard nutrient solution (SNS) or saline wastewater discharged from a greenhouse semi-closed hydroponic (substrate) culture of tomato or a saltwater recirculating aquaculture system (RAS) with Gilthead sea bream (Spaurus aurata L., which was used as such or after dilution (50:50) with SNS. Plant growth was not significantly affected by the composition of irrigation water, while higher antioxidant capacity (measured using the DPPH assay) and concentration of photosynthetic pigments, phenols, flavonoids, and ascorbic acid were found in the shoots of SNS plants than in those of plants irrigated with wastewater. The level of lipid peroxidation and H2O2 production significantly increased in the SNS plants, which also showed higher activity of superoxide dismutase and lower activity of catalase. These results suggest that S. europaea can be cultivated using wastewater with moderate to high salinity discharged from greenhouse hydroponic crops or RASs, and that salt is not strictly required for the growth of this species. Using non-saline nutrient solution can result in moderate oxidative stress that improves the shoot quality of S. europaea.

Genetic Mapping and Characterization of Verticillium Wilt Resistance in a Recombinant Inbred Population of Upland Cotton.

Verticillium wilt (VW) is an important and widespread disease of cotton and once established is long-lived and difficult to manage. In Australia, the non-defoliating pathotype of Verticillium dahliae is the most common, and extremely virulent. Breeding cotton varieties with increased VW resistance is the most economical and effective method of controlling this disease and is greatly aided by understanding the genetics of resistance. This study aimed to investigate VW resistance in 240 F7 recombinant inbred lines (RIL) derived from a cross between MCU-5, which has good resistance, and Siokra 1-4, which is susceptible. Using a controlled environment bioassay, we found that resistance based on plant survival or shoot biomass was complex but with major contributions from chromosomes D03 and D09, with genomic prediction analysis estimating a prediction accuracy of 0.73 based on survival scores compared to 0.36 for shoot biomass. Transcriptome analysis of MCU-5 and Siokra 1-4 roots uninfected or infected with V. dahliae revealed that the two cultivars displayed very different root transcriptomes and responded differently to V. dahliae infection. Ninety-nine differentially expressed genes were located in the two mapped resistance regions and so are potential candidates for further identifying the genes responsible for VW resistance.

Decoding the effects of drought stress on popcorn (Zea mays var. everta) flowering combining proteomics and physiological analysis

Under conditions of soil water limitation and adequate irrigation, we conducted an investigation into the growth dynamics, gas exchange performance, and proteomic profiles of two inbred popcorn lines—L71, characterized as drought-tolerant, and L61, identified as drought-sensitive. Our goal was to uncover the mechanisms associated with tolerance to soil water limitation during the flowering. The plants were cultivated until grain filling in a substrate composed of perlite and peat within 150cm long lysimeter, subjected to two water conditions (WC): i) irrigated (WW) at lysimeter capacity (LC - 100%), and ii) water-stressed (WS). Under WS conditions, the plants gradually reached 45% of LC and were maintained at this level for 10 days. Irrespective of the WC, L71 exhibited the highest values of dry biomass in both shoot and root systems, signifying its status as the most robust genotype. The imposed water limitation led to early senescence, chlorophyll degradation, and increased anthocyanin levels, with a more pronounced impact observed in L61. Traits related to gas exchange manifested differences between the lines only under WS conditions. A total of 1838 proteins were identified, with 169 differentially accumulated proteins (DAPs) in the tolerant line and 386 DAPs in the sensitive line. Notably, differences in energy metabolism, photosynthesis, oxidative stress response, and protein synthesis pathways were identified as the key distinctions between L71 and L61. Consequently, our findings offer valuable insights into the alterations in proteomic profiles associated with the adaptation to soil water limitation in popcorn.

Relic populations of &lt;i&gt;Ranunculus kamtschaticus&lt;/i&gt; DC. (Ranunculaceae) in the Urals

In the context of global climate change, it is of great interest to assess the adaptive capabilities of the glacial relics of the Urals and the prospects for their conservation. Ranunculus kamtschaticus DC. has a high degree of ecological specialization for high mountain conditions and extremely low plasticity. It is preserved in the midlands of the Urals on individual peaks. The life form of R. kamtschaticus in the Ural fragment of its range is a brush-rooted non-turf polycarpic grass with erect assimilating shoots of a non-succulent type. The variability of the development of its shoots and shoot systems under the influence of climatic and weather conditions is shown, the preferential development of shoots with an incomplete development cycle is noted. Irregular fruiting, a long period of germination, and rapid loss of seed germination reduce the competitiveness of R. kamtschaticus in the Urals and its ability to colonize new territories. Threat assessment according to IUCN criteria showed that populations of the species in the Komi Republic and Sverdlovsk region are in critical condition.

A Developed Shear Wave Source for Shallow Seismic Survey

Shear wave velocity is a fundamental parameter in determining geological structures and soil characteristics for geotechnical and earthquake engineering studies. In shallow seismic data acquisition, shear wave is generated by various seismic sources. Although the data quality is affected by the choices of the seismic source, applying highly efficient sources is sometimes limited for some users and by the budget available for a project. Therefore, this work aims to design and develop an effective shear wave seismic source as an alternative for shallow seismic surveys. The developed source consists of 4 main parts, including base plate, activated mass, lifting and shooting system, body and transportation system. It is simply operated by lifting an activated mass with a sling and puller to the armed position. Under this condition, an attached spring is under compression and the maximum potential energy is stored. When the mass is released and horizontally hit the base plate, shear wave is generated by the momentum and energy transferred from the base plate into the ground. To evaluate the source capability, a comparison of the conventional and the developed source was performed at a test site. The recorded data were compared both in qualitative and quantitative manners based on the signal-to-noise ratio, energy and frequency content, signal penetration, and repeatability. It was found that signal energy generated by one blow of the developed source is equivalent to approximately three-fold of the conventional source. There is a remarkably higher repeatability from the developed source than that from the conventional source. Moreover, it is easy to operate, portable, and minimizes required man power. Overall, the new shear source is suitable and has potential application for shallow seismic surveys. HIGHLIGHTS The new shear wave seismic source has been developed and tested as an alternative source for shallow seismic surveys The key advantages of the developed source are that it is simple to operate, reduces required manpower, fairly cost-effective, transportable, safe, and has a minimal environmental impact There is a noticeably higher input signal energy transfer offered by the source leading to the deeper target depth of investigation The better repeatable waveform led to greater accuracy of the 1st break picking in the data processing GRAPHICAL ABSTRACT

Dynamic DNA Methylation Regulates Season-Dependent Secondary Metabolism in the New Shoots of Tea Plants.

Plant secondary metabolites are critical quality-conferring compositions of plant-derived beverages, medicines, and industrial materials. The accumulations of secondary metabolites are highly variable among seasons; however, the underlying regulatory mechanism remains unclear, especially in epigenetic regulation. Here, we used tea plants to explore an important epigenetic mark DNA methylation (5mC)-mediated regulation of plant secondary metabolism in different seasons. Multiple omics analyses were performed on spring and summer new shoots. The results showed that flavonoids and theanine metabolism dominated in the metabolic response to seasons in the new shoots. In summer new shoots, the genes encoding DNA methyltransferases and demethylases were up-regulated, and the global CG and CHG methylation reduced and CHH methylation increased. 5mC methylation in promoter and gene body regions influenced the seasonal response of gene expression; the amplitude of 5mC methylation was highly correlated with that of gene transcriptions. These differentially methylated genes included those encoding enzymes and transcription factors which play important roles in flavonoid and theanine metabolic pathways. The regulatory role of 5mC methylation was further verified by applying a DNA methylation inhibitor. These findings highlight that dynamic DNA methylation plays an important role in seasonal-dependent secondary metabolism and provide new insights for improving tea quality.

EVALUATION OF SOIL CHEMICAL PROPERTIES AND CARROT PERFORMANCE AS INFLUENCED BY INTEGRATED APPLICATION OF POULTRY MANURE AND COCOA POD HUSK IN THE RAINFOREST AGROECOLOGICAL ZONE OF NIGERIA

The high cost of inorganic fertilizer, difficulties involved in its use, its scarcity, coupled with its adverse effects associated with its continuous use on soil quality prompted the need to research into cheap, locally available organic materials to combat soil fertility problems. Field experiments were conducted in 2019 and 2020 to evaluate the effects of the integrated application of poultry manure (PM) and cocoa pod husk (CPH) on soil chemical properties, growth, leaf nutrients content and yield of carrot at Igba in the rainforest ecology of southwest Nigeria. The treatments consisted of PM and CPH each at three levels (0, 5, 10 t ha-1) in a 2 x 3 factorial experiment laid into randomized complete block design with three replicates. Data were collected on soil chemical properties, growth parameters, leaf nutrients content and yield parameters. Data collected were subjected to analysis of variance using Statistical Analysis System Institute Package (SAS, 2000). The soil was slightly acidic (pH 5.5.), low in nitrogen (0.12g kg), available phosphorus (8 mg kg-1). Integrated application of PM and CPH significantly (P&lt; 0.05) improved soil pH, organic carbon, total N, available P, exchangeable bases and lowered exchangeable acidity. Plots with integrated application of PM and CPH had higher values of soil pH, exchangeable bases, ECEC, total N, total organic carbon, available P and lower values of exchangeable acidity and micronutrients than the plots with their sole applications. There were reductions in soil pH, exchangeable bases, ECEC, total N and organic carbon in the control plots in the second cropping seasons. Growth parameters were better enhanced in plots with the integrated application of PM and CPH than either of their sole. There were significant improvements in plant height, leaf length and shoot diameter in the second cropping season in plots amended with PM, CPH and their integrations as against control plots where reductions in the growth characteristics were obtained. The leaf content of N, P, K and Ca were significantly (P&lt; 0.05) enhanced in plots with integrated application of PM and CPH than the plots with their sole application. Carrot root yield characteristics were significantly (P &lt; 0.05) enhanced in plots with the integrated application of PM and CPH than plots with the sole application of PM or CPH. Root yield was increased in the second cropping season in plots treated with the sole application of PM, CPH and their integrations, while there were reductions in root yield parameters in the control plots. Improvements in soil nutrients status, growth, leaf nutrients content and root yield of carrot in both cropping season in the amended plots when compared to the control plots, imply that integrated use of PM and CPH could be used in the enhancement of production of carrot on sustainable basis in the study area.

Дневная и сезонная динамика интенсивности транспирации вереска обыкновенного (Calluna vulgaris (L.) Hill) на юге ареала в Зауралье

The Trans-Ural region is the southern point of the common heather (C. vulgaris) range. Field ecophysiological&#x0D; study of C. vulgaris plants transpiration intensity (IT) was carried out in connection with the problem of marginal populations adaptation to arid climate. The research was carried out in the forest-steppe of the Trans-Ural region (Kurgan&#x0D; region), where an abundant population of heather grows. The dailyvariation of IT was studied taking into account a set&#x0D; of recorded ecoclimate limiting factors (wind speed, illumination, dynamics of air temperature and humidity, soil temperature) during one growing season (from April to September 2016) under the canopy of a pine forest and in the adjacent&#x0D; clearing. To study IT, annual apical shoots of plants 4 cm long were used in triplicate for each time period. The total&#x0D; sample size on one day of measurements ranged from 30-35 shoots. The transpiration rate was determined by the rapid&#x0D; weighing method, which takes into account the water lost by the shoot over a certain time period. When processing the&#x0D; data, we used correlation analysis (Pearson's correlation coefficient r), which made it possible to clarify the strength and&#x0D; direction of two continuous (metric) variables interaction. Differences in IT daily changes were revealed in plants growing&#x0D; under the forest canopy and in the open areas. Under conditions of long-term atmospheric and soil drought, which is&#x0D; common for the region, in 2016 a sharp decrease in heather water content was observed, starting from 10 a.m. throughout&#x0D; the entire growing season, with the exception of April, when the moisture deficit in the soil and heather tissues was still&#x0D; minimal. In May, maximum IT values in the clearing were noted at 14:00 (8.5 mg/h×10 –4) whereas under the canopy of&#x0D; the tree stand, peak IT values begin at 10 a.m. (12.7 mg/h×10 –4). Daytime summer transpiration in common heather (C.&#x0D; vulgaris) is even less intense than spring transpiration ((3–5 mg/h×10–4).It was revealed that meteorological factors play&#x0D; a decisive role in IT in various types of forest. In open felled areas, the determining factor is PAR (0.81, p &lt; 0.05) and, to&#x0D; a lesser extent, atmospheric temperature (0.69, p &lt; 0.05), and under the canopy - only PAR (0.96, p &lt;0.05). A decrease&#x0D; in IT and, accordingly, photosynthesis leads to a decrease in the population’s vitality and non-ripening of seeds, which is&#x0D; an ecophysiological factor of the heather absence south of Kurgan city.

Microbiome structure variation and soybean's defense responses during flooding stress and elevated CO2.

With current trends in global climate change, both flooding episodes and higher levels of CO2 have been key factors to impact plant growth and stress tolerance. Very little is known about how both factors can influence the microbiome diversity and function, especially in tolerant soybean cultivars. This work aims to (i) elucidate the impact of flooding stress and increased levels of CO2 on the plant defenses and (ii) understand the microbiome diversity during flooding stress and elevated CO2 (eCO2). We used next-generation sequencing and bioinformatic methods to show the impact of natural flooding and eCO2 on the microbiome architecture of soybean plants' below- (soil) and above-ground organs (root and shoot). We used high throughput rhizospheric extra-cellular enzymes and molecular analysis of plant defense-related genes to understand microbial diversity in plant responses during eCO2 and flooding. Results revealed that bacterial and fungal diversity was substantially higher in combined flooding and eCO2 treatments than in non-flooding control. Microbial diversity was soil>root>shoot in response to flooding and eCO2. We found that sole treatment of eCO2 and flooding had significant abundances of Chitinophaga, Clostridium, and Bacillus. Whereas the combination of flooding and eCO2 conditions showed a significant abundance of Trichoderma and Gibberella. Rhizospheric extra-cellular enzyme activities were significantly higher in eCO2 than flooding or its combination with eCO2. Plant defense responses were significantly regulated by the oxidative stress enzyme activities and gene expression of Elongation factor 1 and Alcohol dehydrogenase 2 in floodings and eCO2 treatments in soybean plant root or shoot parts. This work suggests that climatic-induced changes in eCO2 and submergence can reshape microbiome structure and host defenses, essential in plant breeding and developing stress-tolerant crops. This work can help in identifying core-microbiome species that are unique to flooding stress environments and increasing eCO2.

Tradeoffs between pH, dissolved organic carbon, and mineral ions regulate cadmium uptake by Solanum hyperaccumulators in calcareous soil

Soil solution pH and dissolved organic carbon (DOC) influence cadmium (Cd) uptake by hyperaccumulators but their tradeoff in calcareous soils is unclear. This study investigated the mechanisms of Solanum nigrum L. and Solanum alatum Moench in calcareous soil using a combination of concentration gradient experiments (0.6–100 mg Cd kg−1) and soil solution composition analysis. The results showed that the soil solution pH of S. nigrum remained stable despite Cd stress. On average, the soil solution pH of S. alatum was 0.23 units higher than that of S. nigrum, although pH decreased significantly under high Cd stress. In addition, the concentrations of potassium (K) and calcium (Ca) in the soil solution of S. nigrum increased and decreased under low and high levels of Cd stress, respectively. In S. alatum, the K and Ca concentrations in the soil solution generally increased with increasing Cd stress levels. Moreover, the level of DOC in the soil solution of both plants was higher under Cd stress compared to the control, and a gradually increasing trend with Cd stress level was observed in S. alatum. Consequently, the bioconcentration factors of the roots (2.62–19.35) and shoots (1.20–9.59) of both plants were >1, while the translocation factors were <1, showing an obstacle of Solanum hyperaccumulators in transferring Cd into their aboveground parts. Redundancy analysis revealed that the Cd concentration in S. nigrum roots was significantly negatively correlated with the soil solutions of K and Ca. In contrast, Cd concentrations in S. alatum roots and shoots were significantly positively correlated with soil solution DOC, K, and Ca but negatively correlated with pH. Our results suggest that calcareous soil neutralizes the acidity of released protons but does not affect cation exchange, inhibiting DOC in assisting the translocation of Cd within plants.

Reduced Growth in Eustoma under High Nutrient and Phytotoxic Organic Acid Concentrations and Recovery through Hot Water Conditioning of Continuously Cropped Soil

Stunted vegetative growth and delayed or absent flowering are commonly observed in eustoma (Eustoma grandiflorum) when cultivated continuously in the same greenhouse soil. These effects are likely caused by the excessive accumulation of soluble salts and/or phytotoxic organic acids in the soil. This study aimed to clarify the mechanism of continuous cropping obstacles and formulate prevention measures of eustoma. Seedlings of eustoma ‘Croma III White’ were grown hydroponically with 0%, 25%, 50%, 75%, 100% (full), 125%, 150%, 175%, or 200% strength of Johnson’s solution. Plant height, leaf area, and shoot dry weight increased steadily as solution strength increased from 25% to 125% [solution electrical conductivity (EC) of 2.4 dS⋅m−1] and then gradually decreased as solution strength further increased from 125% to 200% (solution EC of 3.8 dS⋅m−1). When grown hydroponically in 200% strength Johnson’s solution, plant height, leaf area, and root length increased with increasing equimolar mixtures of organic acids, including maleic acid, benzoic acid, malic acid, and hydroxybenzoic acid, up to 1.2 to 1.6 mM and decreased thereafter. Node number and the percentage of flower bud visibility declined beyond 1.6 mM organic acid mixtures. Plants with 2.0 and 2.4 mM organic acid mixtures had the lowest net photosynthetic rate, stomatal conductance, transpiration, and intercellular carbon dioxide concentration. Plants had normal growth and produced flower buds when the continuously cropped soil was preconditioned with 100 °C reverse-osmosis water before planting.

Pseudoxanthomonas sp. JBR18, a halotolerant endophytic bacterium, improves the salt tolerance of Arabidopsis seedlings

Salinization of land is globally increasing due to climate change, and salinity stress is an important abiotic stressor that adversely affects agricultural productivity. In this study, we assessed a halotolerant endophytic bacterium, Pseudoxanthomonas sp. JBR18, for its potential as a plant growth-promoting agent with multiple beneficial properties. The strain exhibited tolerance to sodium chloride concentration of up to 7.5 % in the R2A medium. In vitro evaluation revealed that strain JBR18 possessed proteolytic, protease (EC 3.4), and cellulase (EC 3.2.1.4) activities, as well as the ability to produce indole-acetic acid, proline, and exopolysaccharides. Compared with the controls, co-cultivation of Arabidopsis seedlings with the strain JBR18 improved plant growth, rosette size, shoot and root fresh weight, and chlorophyll content under salinity stress. Moreover, JBR18-inoculated seedlings showed lower levels of malondialdehyde, reactive oxygen species, and Na+ uptake into plant cells under salt stress but higher levels of K+. Additionally, seedlings inoculated with JBR18 exhibited a delayed response time and quantity of salt-responsive genes RD29A, RD29B, RD20, RD22, and KIN1 under salt stress. These multiple effects suggest that Pseudoxanthomonas sp. JBR18 is a promising candidate for mitigating the negative impacts of salinity stress on plant growth. Our findings may assist in future efforts to develop eco-friendly strategies for managing abiotic stress and enhancing plant tolerance to salt stress.