The genomics of linkage drag in inbred lines of sunflower.

Crop wild relatives represent valuable sources of alleles for crop improvement, including adaptation to climate change and emerging diseases. However, introgressions from wild relatives might have deleterious effects on desirable traits, including yield, due to linkage drag. Here, we analyzed the genomic and phenotypic impacts of wild introgressions in inbred lines of cultivated sunflower to estimate the impacts of linkage drag. First, we generated reference sequences for seven cultivated and one wild sunflower genotype, as well as improved assemblies for two additional cultivars. Next, relying on previously generated sequences from wild donor species, we identified introgressions in the cultivated reference sequences, as well as the sequence and structural variants they contain. We then used a ridge-regression best linear unbiased prediction (BLUP) model to test the effects of the introgressions on phenotypic traits in the cultivated sunflower association mapping population. We found that introgression has introduced substantial sequence and structural variation into the cultivated sunflower gene pool, including >3,000 new genes. While introgressions reduced genetic load at protein-coding sequences, they mostly had negative impacts on yield and quality traits. Introgressions found at high frequency in the cultivated gene pool had larger effects than low-frequency introgressions, suggesting that the former likely were targeted by artificial selection. Also, introgressions from more distantly related species were more likely to be maladaptive than those from the wild progenitor of cultivated sunflower. Thus, breeding efforts should focus, as far as possible, on closely related and fully compatible wild relatives.

Multi-omics-driven advances in the understanding of triacylglycerol biosynthesis in oil seeds.

Vegetable oils are rich sources of polyunsaturated fatty acids and energy as well as valuable sources of human food, animal feed, and bioenergy. Triacylglycerols, which are comprised of three fatty acids attached to a glycerol backbone, are the main component of vegetable oils. Here, we review the development and application of multiple-level omics in major oilseeds and emphasize the progress in the analysis of the biological roles of key genes underlying seed oil content and quality in major oilseeds. Finally, we discuss future research directions in functional genomics research based on current omics and oil metabolic engineering strategies that aim to enhance seed oil content and quality, and specific fatty acids components according to either human health needs or industrial requirements.

Physiological and transcriptomic profiles reveal key regulatory pathways involved in cold resistance in sunflower seedlings.

During sunflower growth, cold waves often occur and impede plant growth. Therefore, it is crucial to study the underlying mechanism of cold resistance in sunflowers. In this study, physiological analysis revealed that as cold stress increased, the levels of ROS, malondialdehyde, ascorbic acid, and dehydroascorbic acid and the activities of antioxidant enzymes increased. Transcriptomics further identified 10,903 DEGs between any two treatments. Clustering analysis demonstrated that the expression of MYB44a, MYB44b, MYB12, bZIP2 and bZIP4 continuously upregulated under cold stress. Cold stress can induce ROS accumulation, which interacts with hormone signals to activate cold-responsive transcription factors regulating target genes involved in antioxidant defense, secondary metabolite biosynthesis, starch and sucrose metabolism enhancement for improved cold resistance in sunflowers. Additionally, the response of sunflowers to cold stress may be independent of the CBF pathway. These findings enhance our understanding of cold stress resistance in sunflowers and provide a foundation for genetic breeding.

Genome-wide identification and characterization of exapted transposable elements in the large genome of sunflower (Helianthus annuus L.).

Transposable elements (TEs) are an important source of genome variability, playing many roles in the evolution of eukaryotic species. Besides well-known phenomena, TEs may undergo the exaptation process and generate the so-called exapted transposable element genes (ETEs). Here we present a genome-wide survey of ETEs in the large genome of sunflower (Helianthus annuus L.), in which the massive amount of TEs, provides a significant source for exaptation. A library of sunflower TEs was used to build TE-specific Hidden Markov Model profiles, to search for all available sunflower gene products. In doing so, 20 016 putative ETEs were identified and further investigated for the characteristics that distinguish TEs from genes, leading to the validation of 3530 ETEs. The analysis of ETEs transcription patterns under different stress conditions showed a differential regulation triggered by treatments mimicking biotic and abiotic stress; furthermore, the distribution of functional domains of differentially regulated ETEs revealed a relevant presence of domains involved in many aspects of cellular functions. A comparative genomic investigation was performed including species representative of Asterids and appropriate outgroups: the bulk of ETEs that resulted were specific to the sunflower, while few ETEs presented orthologues in the genome of all analyzed species, making the hypothesis of a conserved function. This study highlights the crucial role played by exaptation, actively contributing to species evolution.

Mutation and sequencing-based cloning and functional studies of a rust resistance gene in sunflower (Helianthus annuus).

Rust, caused by the fungus Puccinia helianthi Schwein., is one of the most devastating diseases of sunflower (Helianthus annuus L.), affecting global production. The rust R gene R11 in sunflower line HA-R9 shows broad-spectrum resistance to P. helianthi virulent races and was previously mapped to an interval on sunflower chromosome 13 encompassing three candidate genes annotated in the XRQr1.0 reference genome assembly. In the current study, we combined ethyl methane sulfonate (EMS) mutagenesis with targeted region capture and PacBio long-read sequencing to clone the R11 gene. Sequencing of a 60-kb region spanning the R11 locus from the R11 -HA-R9 rust-resistant line and three EMS-induced susceptible mutants facilitated the identification of R11 and definition of induced mutations. The R11 gene is predicted to have a single 3996-bp open reading frame and encodes a protein of 1331 amino acids with CC-NBS-LRR domains typical of genes conferring plant resistance to biotrophic pathogens. Point mutations identified in the R11 rust-susceptible mutants resulted in premature stop codons, consistent with loss of function leading to rust susceptibility. Additional functional studies using comparative RNA sequencing of the resistant line R11 -HA-R9 and R11 -susceptible mutants revealed substantial differences in gene expression patterns associated with R11 -mediated resistance at 7 days post-inoculation with rust, and uncovered the potential roles of terpenoid biosynthesis and metabolism in sunflower rust resistance.

Comparative genomics and host range analysis of four Ralstonia pseudosolanacearum strains isolated from sunflower reveals genomic and phenotypic differences.

BACKGROUND: Bacterial wilt caused by Ralstonia solanacearum species complex (RSSC) is one of the devastating diseases in crop production, seriously reducing the yield of crops. R. pseudosolanacearum, is known for its broad infrasubspecific diversity and comprises 36 sequevars that are currently known. Previous studies found that R. pseudosolanacearum contained four sequevars (13, 14, 17 and 54) isolated from sunflowers sown in the same field. RESULTS: Here, we provided the complete genomes and the results of genome comparison of the four sequevars strains (RS639, RS642, RS647, and RS650). Four strains showed different pathogenicities to the same cultivars and different host ranges. Their genome sizes were about 5.84 ~ 5.94 Mb, encoding 5002 ~ 5079 genes and the average G + C content of 66.85% ~ 67%. Among the coding genes, 146 ~ 159 specific gene families (contained 150 ~ 160 genes) were found in the chromosomes and 34 ~ 77 specific gene families (contained 34 ~ 78 genes) in the megaplasmids from four strains. The average nucleotide identify (ANI) values between any two strains ranged from 99.05% ~ 99.71%, and the proportion of the total base length of collinear blocks accounts for the total gene length of corresponding genome was all more than 93.82%. Then, we performed a search for genomic islands, prophage sequences, the gene clusters macromolecular secretion systems, type III secreted effectors and other virulence factors in these strains, which provided detailed comparison results of their presence and distinctive features compared to the reference strain GMI1000. Among them, the number and types of T2SS gene clusters were different in the four strains, among which RS650 included all five types. T4SS gene cluster of RS639 and RS647 were missed. In the T6SS gene cluster, several genes were inserted in the RS639, RS647, and RS650, and gene deletion was also detected in the RS642. A total of 78 kinds of type III secreted effectors were found, which included 52 core and 9 specific effectors in four strains. CONCLUSION: This study not only provided the complete genomes of multiple R. pseudosolanacearum strains isolated from a new host, but also revealed the differences in their genomic levels through comparative genomics. Furthermore, these findings expand human knowledge about the range of hosts that Ralstonia can infect, and potentially contribute to exploring rules and factors of the genetic evolution and analyzing its pathogenic mechanism.

Genetic control of abiotic stress-related specialized metabolites in sunflower.

BACKGROUND: Abiotic stresses in plants include all the environmental conditions that significantly reduce yields, like drought and heat. One of the most significant effects they exert at the cellular level is the accumulation of reactive oxygen species, which cause extensive damage. Plants possess two mechanisms to counter these molecules, i.e. detoxifying enzymes and non-enzymatic antioxidants, which include many classes of specialized metabolites. Sunflower, the fourth global oilseed, is considered moderately drought resistant. Abiotic stress tolerance in this crop has been studied using many approaches, but the control of specialized metabolites in this context remains poorly understood. Here, we performed the first genome-wide association study using abiotic stress-related specialized metabolites as molecular phenotypes in sunflower. After analyzing leaf specialized metabolites of 450 hybrids using liquid chromatography-mass spectrometry, we selected a subset of these compounds based on their association with previously known abiotic stress-related quantitative trait loci. Eventually, we characterized these molecules and their associated genes. RESULTS: We putatively annotated 30 compounds which co-localized with abiotic stress-related quantitative trait loci and which were associated to seven most likely candidate genes. A large proportion of these compounds were potential antioxidants, which was in agreement with the role of specialized metabolites in abiotic stresses. The seven associated most likely candidate genes, instead, mainly belonged to cytochromes P450 and glycosyltransferases, two large superfamilies which catalyze greatly diverse reactions and create a wide variety of chemical modifications. This was consistent with the high plasticity of specialized metabolism in plants. CONCLUSIONS: This is the first characterization of the genetic control of abiotic stress-related specialized metabolites in sunflower. By providing hints concerning the importance of antioxidant molecules in this biological context, and by highlighting some of the potential molecular mechanisms underlying their biosynthesis, it could pave the way for novel applications in breeding. Although further analyses will be required to better understand this topic, studying how antioxidants contribute to the tolerance to abiotic stresses in sunflower appears as a promising area of research.

Re-evaluating Homoploid Reticulate Evolution in Helianthus Sunflowers.

Sunflowers of the genus Helianthus are models for hybridization research and contain three of the best-studied examples of homoploid hybrid speciation. To understand a broader picture of hybridization within the annual sunflowers, we used whole-genome resequencing to conduct a phylogenomic analysis and test for gene flow between lineages. We find that all annual sunflower species tested have evidence of admixture, suggesting hybridization was common during the radiation of the genus. Support for the major species tree decreases with increasing recombination rate, consistent with hybridization and introgression contributing to discordant topologies. Admixture graphs found hybridization to be associated with the origins of the three putative hybrid species (Helianthus anomalus, Helianthus deserticola, and Helianthus paradoxus). However, the hybridization events are more ancient than suggested by previous work. Furthermore, H. anomalus and H. deserticola appear to have arisen from a single hybridization event involving an unexpected donor, rather than through multiple independent events as previously proposed. This means our results are consistent with, but not definitive proof of, two ancient independent homoploid hybrid speciation events in the genus. Using a broader data set that covers the whole Helianthus genus, including perennial species, we find that signals of introgression span the genus and beyond, suggesting highly divergent introgression and/or the sorting of ancient haplotypes. Thus, Helianthus can be viewed as a syngameon in which largely reproductively isolated species are linked together by occasional or frequent gene flow.

Hydrogen sulfide-mitigated salinity stress impact in sunflower seedlings was associated with improved photosynthesis performance and osmoregulation.

BACKGROUND: Salinity is one major abiotic stress affecting photosynthesis, plant growth, and development, resulting in low-input crops. Although photosynthesis underlies the substantial productivity and biomass storage of crop yield, the response of the sunflower photosynthetic machinery to salinity imposition and how H2S mitigates the salinity-induced photosynthetic injury remains largely unclear. Seed priming with 0.5 mM NaHS, as a donor of H2S, was adopted to analyze this issue under NaCl stress. Primed and nonprime seeds were established in nonsaline soil irrigated with tape water for 14 d, and then the seedlings were exposed to 150 mM NaCl for 7 d under controlled growth conditions. RESULTS: Salinity stress significantly harmed plant growth, photosynthetic parameters, the structural integrity of chloroplasts, and mesophyll cells. H2S priming improved the growth parameters, relative water content, stomatal density and aperture, photosynthetic pigments, photochemical efficiency of PSII, photosynthetic performance, soluble sugar as well as soluble protein contents while reducing proline and ABA under salinity. H2S also boosted the transcriptional level of ribulose 1,5-bisphosphate carboxylase small subunit gene (HaRBCS). Further, the transmission electron microscope showed that under H2S priming and salinity stress, mesophyll cells maintained their cell membrane integrity and integrated chloroplasts with well-developed thylakoid membranes. CONCLUSION: The results underscore the importance of H2S priming in maintaining photochemical efficiency, Rubisco activity, and preserving the chloroplast structure which participates in salinity stress adaptation, and possibly sunflower productivity under salinity imposition. This underpins retaining and minimizing the injury to the photosynthetic machinery to be a crucial trait in response of sunflower to salinity stress.

Comparative transcriptome and coexpression network analysis reveals key pathways and hub candidate genes associated with sunflower (Helianthus annuus L.) drought tolerance.

BACKGROUND: Drought severely limits sunflower production especially at the seedling stage. To investigate the response mechanism of sunflowers to drought stress, we utilized two genotypes of sunflower materials with different drought resistances as test materials. The physiological responses were investigated under well-watered (0 h) and drought-stressed conditions (24 h, 48 h, and 72 h). RESULTS: ANOVA revealed the greatest differences in physiological indices between 72 h of drought stress and 0 h of drought stress. Transcriptome analysis was performed after 72 h of drought stress. At 0 h, there were 7482 and 5627 differentially expressed genes (DEGs) in the leaves of K55 and K58, respectively, and 2150 and 2527 DEGs in the roots of K55 and K58, respectively. A total of 870 transcription factors (TFs) were identified among theDEGs, among which the high-abundance TF families included AP2/ERF, MYB, bHLH,and WRKY. Five modules were screened using weighted gene coexpressionnetwork analysis (WGCNA), three and two of which were positively and negatively, respectively, related to physiological traits. KEGG analysis revealedthat under drought stress, "photosynthesis", "carotenoid biosynthesis", "starch and sucrose metabolism", "ribosome", "carotenoid biosynthesis", "starch and sucrose metabolism", "protein phosphorylation" and "phytohormone signaling" are six important metabolic pathways involved in the response of sunflower to drought stress. Cytoscape software was used to visualize the three key modules, and the hub genes were screened. Finally, a total of 99 important candidate genes that may be associated with the drought response in sunflower plants were obtained, and the homology of these genes was compared with that in Arabidopsis thaliana. CONCLUSIONS: Taken together, our findings could lead to a better understanding of drought tolerance in sunflowers and facilitate the selection of drought-tolerant sunflower varieties.

Mitigation of drought-induced stress in sunflower (Helianthus annuus L.) via foliar application of Jasmonic acid through the augmentation of growth, physiological, and biochemical attributes.

Drought stress poses a significant threat to agricultural productivity, especially in areas susceptible to water scarcity. Sunflower (Helianthus annuus L.) is a widely cultivated oilseed crop with considerable potential globally. Jasmonic acid, a plant growth regulator, plays a crucial role in alleviating the adverse impacts of drought stress on the morphological, biochemical, and physiological characteristics of crops. Experimental detail includes sunflower varieties (Armani Gold, KQS-HSF-1, Parsun, and ESFH-3391), four drought stress levels (0, 25%, 50%, and 75% drought stress), and three levels (0, 40ppm, 80ppm) of jasmonic acid. The 0% drought stress and 0ppm jasmonic acid were considered as control treatments. The experimental design was a completely randomized design with three replicates. Drought stress significantly reduced the growth in all varieties. However, the exogenous application of jasmonic acid at concentrations of 40ppm and 80ppm enhanced growth parameters, shoot and root length (1.93%, 19%), shoot and root fresh weight (18.5%, 25%), chlorophyll content (36%), photosynthetic rate (22%), transpiration rate (40%), WUE (20%), MDA (6.5%), Phenolics (19%), hydrogen peroxide (7%) proline (28%) and glycine betaine (15-30%) under water-stressed conditions, which was closely linked to the increase in stomatal activity stimulated by jasmonic acid. Furthermore, JA 80 ppm was found to be the most appropriate dose to reduce the effect of water stress in all sunflower varieties. It was concluded that the foliar application of JA has the potential to enhance drought tolerance by improving the morphological, biochemical, and physiological of sunflower.

Heritable differences in abundance of bacterial rhizosphere taxa are correlated with fungal necrotrophic pathogen resistance.

Host-microbe interactions are increasingly recognized as important drivers of organismal health, growth, longevity and community-scale ecological processes. However, less is known about how genetic variation affects hosts' associated microbiomes and downstream phenotypes. We demonstrate that sunflower (Helianthus annuus) harbours substantial, heritable variation in microbial communities under field conditions. We show that microbial communities co-vary with heritable variation in resistance to root infection caused by the necrotrophic pathogen Sclerotinia sclerotiorum and that plants grown in autoclaved soil showed almost complete elimination of pathogen resistance. Association mapping suggests at least 59 genetic locations with effects on both microbial relative abundance and Sclerotinia resistance. Although the genetic architecture appears quantitative, we have elucidated previously unexplained genetic variation for resistance to this pathogen. We identify new targets for plant breeding and demonstrate the potential for heritable microbial associations to play important roles in defence in natural and human-altered environments.

The genomic basis of nitrogen utilization efficiency and trait plasticity to improve nutrient stress tolerance in cultivated sunflower.

Maintaining crop productivity is challenging as population growth, climate change, and increasing fertilizer costs necessitate expanding crop production to poorer lands whilst reducing inputs. Enhancing crops' nutrient use efficiency is thus an important goal, but requires a better understanding of related traits and their genetic basis. We investigated variation in low nutrient stress tolerance in a diverse panel of cultivated sunflower genotypes grown under high and low nutrient conditions, assessing relative growth rate (RGR) as performance. We assessed variation in traits related to nitrogen utilization efficiency (NUtE), mass allocation, and leaf elemental content. Across genotypes, nutrient limitation generally reduced RGR. Moreover, there was a negative correlation between vigor (RGR in control) and decline in RGR in response to stress. Given this trade-off, we focused on nutrient stress tolerance independent of vigor. This tolerance metric correlated with the change in NUtE, plasticity for a suite of morphological traits, and leaf element content. Genome-wide associations revealed regions associated with variation and plasticity in multiple traits, including two regions with seemingly additive effects on NUtE change. Our results demonstrate potential avenues for improving sunflower nutrient stress tolerance independent of vigor, and highlight specific traits and genomic regions that could play a role in enhancing tolerance.

Added γ-oryzanol boosted anti-inflammatory effects of canola oil in adult subjects with type 2 diabetes: a randomized controlled clinical trial.

PURPOSE: This study was conducted to examine the effects of daily intake of γ-oryzanol (ORZ)-fortified canola oil, as compared with plain canola and sunflower oils, on certain inflammatory and oxidative stress biomarkers in adult subjects with Type 2 Diabetes (T2D). METHODS: We randomly allocated 92 adult subjects with T2D from both sexes to one of the following groups to receive: (a) ORZ-fortified canola oil (ORZO; n1 = 30); (b) unfortified canola oil (CANO; n2 = 32); or (c) sunflower oil (SUFO; n3 = 30) for 12 weeks. Dietary and laboratory evaluations were performed initially and finally. RESULTS: Serum hs-CRP concentrations significantly decreased in ORZO group (from 3.1 ± 0.2 to 1.2 ± 0.2 mg/L), as compared with CANO (p = 0.003) and SUFO (p < 0.001) groups. Serum IL-6 significantly decreased just in ORZO (- 22.8%, p = 0.042) and CANO groups (- 19.8%, p = 0.038). However, the between-group differences were not significant. Serum IL-1ß slightly decreased in ORZO (- 28.1%, p = 0.11) and increased in SUFO (+ 20.6%, p = 0.079) but between-group difference was statistically significant (p = 0.017). Serum IFN-γ concentrations decreased significantly only in ORZO (from 3.3 ± 0.08 to 2.9 ± 0.21 IU/mL, p = 0.044). Salivary IgA concentrations increased significantly in all three intervention groups. Notwithstanding, only the difference between ORZO and CANO groups was statistically significant (p = 0.042). Similarly, circulating malondialdehyde concentrations significantly decreased in all three groups but with no between-group significant difference. CONCLUSIONS: Daily consumption of ORZ-fortified canola oil, compared with unfortified canola and sunflower oils, for 12 weeks resulted in boosting of certain anti-inflammatory effects of canola oil. These findings may have preventive implications for both clinicians and policy makers. This clinical trial was registered at clinicaltrials.gov (03.08.2022; NCT05271045).

Bioleaching of Cd from contaminated Helianthus annuus L. stalk and the safe utilization of its byproducts by Aspergillus niger.

Disposal and recycling of heavy metal-enriched biomass is the key to measure the success of phytoremediation. This study employed innovative approach to use Aspergillus niger (A. niger) for the treatment of Cd-contaminated Helianthus annuus L. (sunflower) stalk after phytoremediation. Single-factor results showed that the removal of Cd at an initial pH of 3 was superior to sucrose and inoculation amount. 67.67% of Cd was removed by A. niger leaching system after 11 days based on response surface methodology optimum conditions (sucrose: 76.266 g L-1; inoculation amount: 10%; initial pH: 3), while the concentrations of nitrogen, phosphorus and potassium (N, P and K) of sunflower stalk were unaffected. While physicochemical pretreatment effectively enhanced the bioleaching efficiency, it also resulted in significant loss of P and K elements, thereby reducing the value of biomass for recycling and utilization. Therefore, the direct A. niger leaching method without pretreatment is more advantageous for the safe treatment and recycling of Cd-contaminated sunflower stalks.

Integrated transcriptome and metabolome analysis revealed that HaMYB1 modulates anthocyanin accumulation to deepen sunflower flower color.

KEY MESSAGE: HanMYB1 was found to play positive roles in the modulation of anthocyanins metabolism based on the integrative analysis of different color cultivars and the related molecular genetic analyses. As a high value ornamental and edible crop with various colors, sunflowers (Helianthus annuus L.) provide an ideal system to understand the formation of flower color. Anthocyanins are major pigments in higher plants, which is associated with development of flower colors and ability of oxidation resistance. Here, we performed an integrative analysis of the transcriptome and flavonoid metabolome in five sunflower cultivars with different flower colors. According to differentially expressed genes and differentially accumulated flavonoids, these cultivars could be grouped into yellow and red. The results showed that more anthocyanins were accumulated in the red group flowers, especially the chrysanthemin. Some anthocyanins biosynthesis-related genes like UFGT (UDP-glycose flavonoid glycosyltransferase) also expressed more in the red group flowers. A MYB transcriptional factor, HanMYB1, was found to play vital positive roles in the modulation of anthocyanins metabolism by the integrative analysis. Overexpressed HanMYB1 in tobacco could deepen the flower color, increase the accumulation of anthocyanins and directly active the express of UFGT genes. Our findings indicated that the MYB transcriptional factors provide new insight into the dynamic regulation of the anthocyanin biosynthesis in facilitating sunflower color formation and anthocyanin accumulation.

Monitoring of parasite Orobanche cumana using Vis-NIR hyperspectral imaging combining with physio-biochemical parameters on host crop Helianthus annuus.

KEY MESSAGE: This study provided a non-destructive detection method with Vis-NIR hyperspectral imaging combining with physio-biochemical parameters in Helianthus annuus in response to Orobanche cumana infection that took insights into the monitoring of sunflower weed. Sunflower broomrape (Orobanche cumana Wallr.) is an obligate weed that attaches to the host roots of sunflower (Helianthus annuus L.) leading to a significant reduction in yield worldwide. The emergence of O. cumana shoots after its underground life-cycle causes irreversible damage to the crop. In this study, a fast visual, non-invasive and precise method for monitoring changes in spectral characteristics using visible and near-infrared (Vis-NIR) hyperspectral imaging (HSI) was developed. By combining the bands sensitive to antioxidant enzymes (SOD, GR), non-antioxidant enzymes (GSH, GSH + GSSG), MDA, ROS (O2-, OH-), PAL, and PPO activities obtained from the host leaves, we sought to establish an accurate means of assessing these changes and conducted imaging acquisition using hyperspectral cameras from both infested and non-infested sunflower cultivars, followed by physio-biochemical parameters measurement as well as analyzed the expression of defense related genes. Extreme learning machine (ELM) and convolutional neural network (CNN) models using 3-band images were built to classify infected or non-infected plants in three sunflower cultivars, achieving accuracies of 95.83% and 95.83% for the discrimination of infestation as well as 97.92% and 95.83% of varieties, respectively, indicating the potential of multi-spectral imaging systems for early detection of O. cumana in weed management.

Mitigating the detrimental impacts of low- and high-density polyethylene microplastics using a novel microbial consortium on a soil-plant system: Insights and interactions.

The accumulation of polyethylene microplastics (PE-MPs) in soil has raised considerable concerns; however, the effects of their persistence and mitigation on agroecosystems have not been explored. This study aimed to assess the detrimental effects of PE-MPs on a soil-plant system and evaluate their mitigation using a novel microbial consortium (MC). We incorporated low-density polyethylene (LDPE) and high-density polyethylene (HDPE) at two different concentrations, along with a control (0 %, 1 %, and 2 % w/w) into the sandy loam soil for a duration of 135 days. The samples were also treated with a novel MC and incubated for 135 days. The MC comprised three bacterial strains (Ralstonia pickettii (MW290933) strain SHAn2, Pseudomonas putida strain ShA, and Lysinibacillus xylanilyticus XDB9 (T) strain S7-10F), and a fungal strain (Aspergillus niger strain F1-16S). Sunflowers were subsequently cultivated, and physiological growth parameters were measured. The results showed that adding 2 % LDPE significantly decreased soil pH by 1.06 units compared to the control. Moreover, adding 2 % HDPE resulted in a more significant decrease in soil electrical conductivity (EC) relative to LDPE and the control. A dose-dependent increase in dissolved organic carbon (DOC) was observed, with the highest DOC found in 2 % LDPE. The addition of higher dosages of LDPE reduced soil bulk density (BD) more than HDPE. The addition of 2 % HDPE increased the water drop penetration time (WDPT) but decreased the mean weight diameter of soil aggregates (MWD) and water-stable aggregates (WSA) compared to LDPE. The results also revealed that higher levels of LDPE enhanced soil basal respiration (BR) and microbial carbon biomass (MBC). The interaction of MC and higher MP percentages considerably reduced soil pH, EC, BD, and WDPT but significantly increased soil DOC, MWD, WSA, BR, and MBC. Regarding plant growth, incorporating 2 % PE-MPs significantly reduced physiological responses of sunflower: chlorophyll content (Chl; -15.2 %), Fv/Fm ratio (-25.3 %), shoot dry weight (ShD; -31.3 %), root dry weight (RD; -40 %), leaf area (LA; -38.4 %), and stem diameter (StemD; -25 %) compared to the control; however, the addition of novel MC considerably reduced and ameliorated the harmful effects of 2 % PE-MPs on the investigated plant growth responses.

Chromatographic Evaluation and Characterization of Constituents of Sunflower Seed Extract Used as Food Additives.

Sunflower seed extract, an antioxidant agent registered on the List of Existing Food Additives in Japan, was evaluated using HPLC, and three common constituents were detected. These peaks were identified as monocaffeoylquinic acids (3-O-caffeoylquinic acid, 4-O-caffeoylquinic acid, and 5-O-caffeoylquinic acid [chlorogenic acid]). Upon scrutinizing other components, dicaffeoylquinic acids (isochlorogenic acids; 3,4-di-O-caffeoylquinic, 3,5-di-O-caffeoylquinic, and 4,5-di-O-caffeoylquinic acids) were also identified. Structures of two newly isolated compounds were determined to be 3-O-(3S-2-oxo-3-hydroxy-indole-3-acetyl)-5-O-caffeoylquinic and 4-O-(3S-2-oxo-3-hydroxy-indole-3-acetyl)-5-O-caffeoylquinic acids. To identify the components that contribute to the antioxidant activity of sunflower seed extract, we fractionated the food additive sample solution and examined the active fractions for 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity. Monocaffeoylquinic and dicaffeoylquinic acids showed high DPPH activity, including their contribution to the antioxidant activity of this food additive. DPPH radical scavenging activity of the new compounds showed almost the same value as that of the positive control, Trolox. Therefore, the contribution of these compounds was also considered.

Morphological and Molecular Characterization of Bacterial Pathogens Associated with Leaf Mottle of Sunflower in Northern Kazakhstan.

Leaf mottle is a serious disease in the common sunflower (Helianthus annuus L.), which affects plant growth and development and seed quality and yield. Over the past few years, the North Kazakhstan region, a sunflower-producing area in Kazakhstan, has been seriously affected by leaf mottle. Since 2021, symptomatic leaves have been collected from production areas of this base to determine the pathogens causing sunflower foliar diseases. One hundred bacterial strains were isolated, and two genera and five species were identified based on morphological characteristics, molecular genetics, and phylogenetic analysis (16S gene region). The genus Bacillus was represented by four species: Bacillus subtilis, B. megaterium, B. amyloliquefaciens, and B. flexus. The genus Paenibacillus was represented by one species, P. peoriae. Pathogenicity experiments showed that B. subtilis, B. megaterium, B. flexus, and P. peoriae could cause leaf mottle disease symptoms. However, disease symptoms caused by B. flexus were highly similar to those observed on infected leaves under natural conditions in the field. Therefore, these bacterial isolates were found to be the primary pathogens causing sunflower leaf mottle, and B. flexus was the most common and virulent pathogen in this study. In addition, this is the first report of B. megaterium, B. flexus, and P. peoriae as pathogens associated with sunflower leaf mottle in Kazakhstan.