Search Results (167)

Sunflower broomrape (Orobanche cumana Wallr. var. helianthi) is traditionally regarded as strictly host-specific, parasitizing cultivated sunflower (Helianthus annuus L.). Arctium lappa L. (burdock) was recently identified as a novel susceptible host, but whether this susceptibility is uniform across different sunflower O. cumana races remained unknown. Here, three naturally occurring A. lappa populations from north-eastern Bulgaria and a susceptible sunflower inbred line (AD-66) were challenged under controlled glasshouse conditions with three O. cumana races of increasing virulence (F, G, and G+/H), and tubercle number was recorded 45 days after inoculation (n = 50 plants per host × race combination). Race F was largely unable to establish infection on A. lappa (0–4% infected plants) while remaining highly infective on sunflower (96%), whereas races G and G+/H retained substantial infectivity on A. lappa (68–96%), though with up to two-to-three-fold lower mean tubercle numbers than on sunflower. A negative binomial generalized linear model showed that race accounted for the largest share of explained variation in tubercle number, with weaker and less robust host and host × race effects. Additive Main Effects and Multiplicative Interaction (AMMI) and genotype plus genotype-by-environment (GGE) biplot analyses further resolved this interaction into a single dominant axis, along which A. lappa was disproportionately susceptible to race G+/H and disproportionately resistant to race F. These results demonstrate that, under controlled glasshouse conditions, A. lappa is a race-dependent, alternative host for O. cumana. Whether this translates into a field-relevant reservoir capacity beyond the sunflower cropping cycle remains to be established. Full article

Modern agriculture faces critical challenges, including climate change, soil degradation, and reliance on synthetic inputs, necessitating sustainable alternatives. A promising approach is applying microbial solutions. This study investigated the effects of a commercially available powder-formulated seed coating product containing Rhizoglomus irregularis and Azospirillum spp. on high-linoleic sunflower (Helianthus annuus L.) under field conditions at three Hungarian sites with contrasting soil properties. Plant growth parameters, yield, and the rhizosphere’s microbial carbon-source utilisation potential were assessed to evaluate treatment effects. Seed-applied inoculation increased plant height, stem diameter, and biomass, although responses varied with site conditions and sampling time. The agronomic response was highly site-dependent: the strongest effect was observed at a low-pH, phosphorus-limited site, where seed inoculation achieved a significant yield increase of 18–21%, while effects at sites with higher pH and sufficient phosphorus resulted only in minor, statistically non-significant numerical trends. Distinct shifts in culture-dependent carbon-source utilisation potential were detected by Biolog EcoPlate™ analysis, showing temporal and site-specific variability. These results indicate that seed-applied formulations offer a logistically feasible, targeted delivery method for plant-beneficial microbes, with their agronomic efficacy fundamentally governed by site-specific soil chemical profiles and baseline nutrient availability. Overall, the agronomic benefits of inoculation appear to be context-dependent and more pronounced under nutrient-limited conditions, highlighting the critical importance of site-specific application strategies and the need for further long-term studies. Full article

In dormant sunflower achenes, several structures—the pericarp, seed coat and embryo—contribute to the repression of germination. Achene dormancy varies widely among cultivated sunflower genotypes, and understanding its transmission to hybrid progeny is important both for hybrid seed production and for clarifying the role of these structures. This study examined the inheritance of dormancy in the F1 progeny, with particular emphasis on thermo-inhibition (inhibition of germination at warm temperatures). Reciprocal crosses were performed using three oilseed inbred lines with contrasting dormancy phenotypes. Germination of achenes, seeds, and embryos was tested at 10 and 30 °C at harvest and during postharvest, together with hormonal responses (abscisic acid, ethylene and gibberellins) and measurements of endogenous ABA levels. Results show that maternally inherited, pericarp-imposed thermo-inhibition depends on the dormancy level of the hybrid embryo, which follows a zygotic pattern with incomplete dominance. While embryo sensitivity to ABA related positively with thermo-inhibition, surprisingly, embryonic ABA content was inversely related to dormancy level across genotypes. These findings provide new insight into physiological control of achene dormancy in sunflower and contribute to improved breeding strategies for high-quality hybrid seed. Full article

Acetolactate synthase (ALS; EC 2.2.1.6) catalyzes the first committed step in branched-chain amino acid (BCAA) biosynthesis and is the molecular target of multiple herbicide classes, including the imidazolinones. Here, we performed a genome-wide characterization of the HaALS gene family in sunflower (Helianthus annuus L.) and investigated genotype-dependent transcriptional responses to imazethapyr. A total of 11 HaALS genes were identified and classified into three phylogenetic clades (Groups A–C). All HaALS proteins contained the conserved TPP_enzyme domains (TPP_enzyme_N, TPP_enzyme_M, and TPP_enzyme_C), and purifying selection (Ka/Ks < 1) indicated strong evolutionary constraint on their core enzymatic function. Promoter analyses revealed abundant cis-regulatory elements associated with diverse stress and signaling inputs, supporting regulatory potential for herbicide-triggered transcriptional modulation. qRT-PCR analysis following imazethapyr application (0, 24, and 48 h) showed pronounced genotype-dependent expression reprogramming between the susceptible (S) and resistant (R) cultivars. In the R genotype, multiple HaALS members were strongly induced after treatment; specifically, HaALS4 reached a ~6-fold increase at 24 h and a >10-fold increase at 48 h, and HaALS11 increased to ~6–7-fold at 24 h while remaining above the baseline at 48 h; several additional paralogs exhibited intermediate induction (~3–8-fold by 48 h). In contrast, the S genotype showed limited changes (typically ~0.8–2-fold). Collectively, these findings define the evolutionary features of the sunflower HaALS family and identify herbicide-responsive paralogs that may contribute to imidazolinone tolerance, providing candidates for functional validation and molecular breeding. Full article

Heavy metal (HM) contamination near mining operations in Kazakhstan poses a serious threat to the environment. However, data on the state of chernozem soils in this region is limited. This study assessed the bioaccumulation of HMs and translocation within the soil–sunflower (Helianthus annuus L.) system in a southern Calcic Chernozem in the Kostanay region (Northern Kazakhstan), which is located 50 km from the nearest mining facility. The content of seven HMs (Cd, Co, Cr, Cu, Ni, Pb, and Zn) and arsenic (As), as well as five macroelements (K, Ca, S, Mg, and P), was determined in 18 soil samples from the complete soil pedon (0–150 cm) and in eight anatomical parts of six sunflower plants at physiological maturity. Most metals exhibited a deficiency relative to upper continental crustal Clarke values (Clarke of Concentration (CC) < 1 for Cr, Cu, Ni, Pb, and Zn), with a moderate lithogenic anomaly for Cd (CC = 1.65–3.57) and a localized Co anomaly in the Bk horizon (56.26 mg kg⁻¹), indicating no pronounced HM contamination at the investigated agricultural site. Metal distribution exhibited strong organ specificity in sunflower plants. Cd, Cu, and Zn accumulated preferentially in the leaves, whereas Ni and Co were more concentrated in the seeds and stems, respectively. Only cadmium exceeded the threshold values for both BCF > 1 (1.01) and TF > 1 (1.47), confirming the status of sunflower as a cadmium accumulator. These results provide a preliminary reference dataset of the organ-specific distribution of heavy metals in H. annuus L. plants, which can serve as a local baseline for sunflower growth in uncontaminated southern Chernozems. This information can contribute to future environmental monitoring purposes in the region, acting as an exploratory benchmark. Full article

Silages produced from different forage species exhibit substantial variability in chemical composition, digestibility, and fermentation characteristics, which may influence forage quality and preservation efficiency in livestock systems. This study evaluated the nutritional and fermentative variability of silages produced from six forage species (Zea mays L., Sorghum bicolor L., Medicago sativa L., Helianthus annuus L., Cenchrus purpureus, and Saccharum officinarum L.) using multivariate analytical approaches. A database comprising 237 observations, obtained from 24 independent ensiling experiments, was analyzed. Chemical composition, fermentative parameters, and in vitro dry matter digestibility were evaluated through principal component analysis (PCA), canonical discriminant analysis (CDA), and Pearson correlation analysis. Significant differences among forage species were detected (p < 0.05). PCA explained 76.2% of the total variance in the chemical dataset and 85.1% in the fermentative dataset, revealing clear multivariate patterns among silage types. Chemical composition traits provided greater discrimination among silages than fermentative variables, particularly through differences in fiber fractions, soluble carbohydrates, digestibility, and buffering capacity. Corn and sorghum silages were associated with greater starch availability and favorable fermentation profiles, whereas elephant grass and sugarcane exhibited higher fiber concentrations. Alfalfa showed greater crude protein concentration and digestibility, while sunflower was characterized by elevated lignin concentration. Overall, multivariate analyses provided an integrated interpretation of nutritional and fermentative relationships among silages, highlighting species-specific responses to ensiling and their implications for forage conservation and livestock production systems. Full article

Plant lecithins are complex mixtures of phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI), phosphatidic acid (PA) and lysophospholipids. They are increasingly demanded as natural, non-allergenic emulsifiers and as nutraceutical carriers. Quantitative data on the phospholipid (PL) fraction of less-commodity oilseeds, however, remain dispersed. This review compares the PL composition, processing-dependent extractability, and functional behavior of six oils: hemp (Cannabis sativa L.), sunflower (Helianthus annuus L.), corn/maize (Zea mays L., germ), pumpkin (Cucurbita spp.), flax/linseed (Linum usitatissimum L.), and camelina (Camelina sativa L.). Across the six oils, total PL content varies by more than an order of magnitude (c.a. 0.25% in camelina oil bodies; >1% in solvent-extracted hemp and c.a. 0.5–1.0% in Styrian pumpkin oil), and PC fraction ranges from 30% (hemp seed tissue) to 56% (rapeseed-comparable sunflower). Flax stands out for both an exceptionally high PE share (22.7%) and a polyunsaturated fatty acid (PUFA) content in the PL fraction (53.3%) that exceeds rapeseed, sunflower and soy by an order of magnitude. We integrate recent extraction (cold pressing, supercritical CO₂, microwave-assisted, aqueous enzymatic) and degumming data (water, acid, enzymatic with phospholipases A1/A2/C) with functional evidence in emulsions, oil bodies, and bioactive delivery. Full article

Small heat shock proteins (Hsp20s) function as essential molecular chaperones in plant stress responses, yet their genome-wide characterization in sunflower (Helianthus annuus L.) remains lacking and their functional role in heat response is also unknown. In this study, 65 HaHsp20 genes were identified in sunflower through a comprehensive genome-wide analysis based on the conserved ACD (α-crystallin) domain. The expansion of this family was primarily driven by whole-genome duplication (WGD) or segmental duplication events, with the CI subfamily (20 members) representing the most significantly expanded lineage-specific clade. While all HaHsp20 proteins harbor the conserved α-crystallin domain (ACD), they exhibit diverse molecular weights (11.31–53.35 kDa), isoelectric points (4.71–9.75), and subcellular localization patterns. Promoter cis-regulatory element analysis revealed a predominance of ABA and MeJA-responsive elements but only two canonical heat shock elements. Transcriptome and RT-qPCR analyses revealed that most HaHsp20 genes are responsive to heat stress, with seven HaHsp20 genes exhibiting extremely upregulated expression (more than 1000-fold) after 10 h of 45 °C treatment. Among these, HaHsp21.59 and HaHsp25.91 showed an increase of over 4000-fold in expression. These findings provide a comprehensive foundation for understanding the evolutionary history and expression dynamics of the HaHsp20 family in sunflower, and highlight HaHsp21.59 and HaHsp25.91 as promising candidate genes for future functional validation of their potential roles in heat stress tolerance. Full article

Background/Objectives: Sunflower (Helianthus annuus L.) is one of the four major oil crops worldwide and possesses strong stress tolerance. However, salt stress remains limiting in the improvement of sunflower yield and quality. Methods: In this study, the salt-tolerant cultivar P50 and salt-sensitive cultivar P29 were used as experimental materials to conduct transcriptome sequencing on root and leaf samples treated with NaCl. Subsequently, the molecular mechanisms underlying salt tolerance in sunflower were revealed through assembly and splicing, functional annotation, differential expression analysis, enrichment analysis, and transcription factors (TFs) prediction. Results: Results showed that 54,860,184 and 60,601,572 high-quality clean reads were obtained from the two cultivars, respectively. A total of 110,751 all-unigenes were generated after assembly and clustering, of which 77,536 were functionally annotated. A total of 21,332 differentially expressed genes (DEGs) were identified, including 10,306 upregulated and 11,026 downregulated genes. Quantitative real-time PCR validation of 15 DEGs showed a 93.33% consistency rate with the sequencing data. GO enrichment analysis indicated that DEGs were significantly enriched in pathways related to antioxidant enzyme activities. KEGG enrichment analysis demonstrated that DEGs were primarily involved in 15 carbohydrate metabolism pathways, especially starch and sucrose metabolism. In addition, 67 differentially expressed TF families containing 528 DEGs were identified, including bHLH, AP2/ERF-ERF, MYB, C3H, WRKY, EREBP, B3-ARF, and NAC. Conclusions: Our study constructed a comprehensive transcription map of the sunflower response to salt stress and systematically elucidated the molecular mechanisms underlying salt tolerance. The salt-tolerant sunflower cultivar P50 exhibits an efficient salt stress defense system via three core strategies: (i) activating the antioxidant system to rapidly scavenge excess reactive oxygen species and mitigate oxidative damage; (ii) regulating carbohydrate metabolism through starch and sucrose redistribution to provide energy and osmotic protection against physiological drought; and (iii) mobilizing multiple TF families to establish a complex regulatory network for the precise control of downstream functional genes. Full article

The expression of two genes, Fum1 and Fum2, encoding the mitochondrial and cytosolic forms of fumarase (EC 4.2.1.2); the methylation of individual CpGs of their promoters; and fumarase activity were studied in sunflower (Helianthus annuus L.) leaves depending on irradiation and salinity. Fumarase activity was twice as high in darkness compared to irradiation by white light and red light, while far-red light applied after darkness or after red light reverted the activity to the values in darkness, which indicates the involvement of phytochrome. Using qRT-PCR, it was demonstrated that this corresponded to the pattern of expression of the Fum1 gene, while the expression of the Fum2 gene was higher upon irradiation by white and red light, and lower in darkness and under far-red light. Under the application of 150 mM NaCl for 1, 3, 6, 12, and 24 h, fumarase activity increased fivefold from the start of incubation to 6 h, and then decreased after 12 h. These changes were associated with the transcriptional regulation of the Fum1 and Fum2 genes. Changes in the methylation status of the analyzed CpGs in their gene promoters, detected via semi-quantitative methylation-specific PCR, were associated with differences in their expression. The higher methylation levels of the analyzed CpGs in the Fum1 gene promoter under different light conditions and in the Fum2 gene promoter under salinity corresponded to low levels of their transcripts in sunflower leaves. It is suggested that the mitochondrial and cytosolic forms of fumarase are regulated by light and salinity at the gene expression level, presumably through changes in the methylation status of individual CpGs in their promoters. Full article

Plant height is a key component of sunflower (Helianthus annuus L.) plant architecture. It strongly influences lodging resistance, mechanized harvestability, and yield stability. However, the genetic basis of plant height in sunflowers remains underexplored. This study aimed to develop an F₂ population consisting of 715 individuals from a cross between the dwarf inbred line 150A and the tall inbred line PT326. Bulked segregant analysis coupled with whole-genome resequencing was employed to identify loci associated with plant height. Using three complementary analytical methods, a major quantitative trait locus, qPH15, was identified on chromosome 15. This locus was subsequently fine-mapped, using Kompetitive Allele Specific PCR (KASP) markers and recombinant screening in F₂ and F₃ populations, narrowing it to a 64.66-kb region containing three annotated genes. Among these, HanXRQr2_Chr15g0707451, which encodes an NAC transcription factor designated HaNAC7, was identified as the most promising candidate gene. Haplotype analysis of HaNAC7 across 148 sunflower accessions revealed 4 polymorphic sites defining 6 haplotypes with substantial differences in plant height. The shortest haplotypes, Hap2 and Hap3, were associated with reduced plant height and were predominantly found in Asian germplasm. These findings suggest that HaNAC7 is a strong candidate gene underlying qPH15 and provide useful molecular markers and favorable allelic resources for improving sunflower plant architecture. Full article

Summer cover crops can improve soil fertility and contribute to nitrogen (N) supply in temperate cropping systems, yet the effects of mixture composition and sowing timing remain insufficiently documented. This study evaluated biomass production and N accumulation of five multispecies cover crop mixtures grown in Estonia during 2024–2025 under two sowing dates per year. Aboveground biomass, botanical composition, and carbon (C) and nitrogen concentrations were measured to assess productivity, species contributions, and residue quality. Earlier sowing was generally associated with higher biomass and N accumulation, with first-sown mixtures producing, on average, 38.7% more biomass than later-sown mixtures. Mixture performance was strongly shaped by species composition and competitive hierarchies. Total N accumulation of the cover crop mixtures ranged from 42 to 275 kg N ha⁻¹ depending on mixture composition and sowing time, with mixtures dominated by common vetch (Vicia sativa L.) achieving the highest values. Oat (Avena sativa) dominated and contributed substantially to biomass in mixtures lacking competitive legumes, whereas sunflower (Helianthus annuus) and maize (Zea mays) performed less well under delayed sowing. Low-growing species such as Persian clover (Trifolium resupinatum) produced little biomass when grown with highly competitive species. Legumes exhibited lower C:N ratios than non-legumes, while mixture-level values remained moderate, suggesting residue quality with potential for favourable decomposition and nutrient release in summer cover crop systems under temperate conditions. Full article

Hydrochar has emerged as a promising carbonaceous amendment to enhance soil quality, yet its short-term effects on soil carbon (C) and nitrogen (N) dynamics and microbial functioning remain poorly understood. Here, a 77-day greenhouse pot experiment was conducted using a Cambisol cultivated with sunflower (Helianthus annuus L.) under two irrigation regimes simulating well-irrigated (WI) and water-deficit (WD) scenarios. Two doses of chicken-manure-derived hydrochar (3.25 and 6.5 t ha⁻¹, corresponding to 2.35 and 4.69 g kg⁻¹ of dry soil, respectively) and mineral fertilizer (MF) treatments providing equivalent N inputs were evaluated. Hydrochar promoted microbial growth and enhanced enzymatic and respiratory activities despite its low apparent C and nutrient input. After 77 days under WI, the addition of 6.5 t ha⁻¹ hydrochar enhanced the activity of phenol oxidase (POA) and acid phosphomonesterase (AcPA). Concomitantly, the availability of soluble C and N increased, whereas total organic C (TOC) and N decreased relative to the initial values. These responses may suggest enhanced mineralization potentially related to early-stage priming processes. The increase in POA relative to β-glucosidase is in line with a functional shift from a predominant degradation of labile compounds towards an increased oxidation of more complex structures. This interpretation is supported by solid-state ¹³C NMR data, revealing a higher degradation index of the soil organic matter. Under WD, the overall effects of hydrochar were attenuated or suppressed, particularly those related to C and N dynamics, emphasizing the interactive influence of moisture and amendment dose. Overall, our results show that hydrochar can modulate short-term soil biochemical processes, partly through enhanced microbial responses. Full article

Shoot branching, as an important architectural trait, influences the number of flower heads and the pattern of flowering in sunflowers (Helianthus annuus L.). However, the main genetic factors leading to extensive branching throughout the plant were not clearly understood. In this study, we analyzed branching inheritance and identified a significant locus using an F₂ population (n = 660) from a cross between the non-branched line 150A and the highly branched line PT326. The branching phenotypes varied from having no branches to complete plant branching, with segregation fitting a 3:1 ratio (χ² = 2.916, p > 0.05), suggesting that a single major gene controls this trait, with the non-branched phenotype being dominant. Using bulked segregant analysis (BSA) and whole-genome resequencing, a strong and consistent signal was identified on chromosome 10 across three separate statistical analyses, pinpointing a primary candidate interval of approximately 3.40 Mb, named qBr10. Through the use of 10 developed Kompetitive Allele-Specific PCR (KASP) markers and recombinant screening, qBr10 was restricted to a 388.5 kb (Chr10:13,422,378–13,780,875). Analysis of this interval identified 21 genes, among which WRKY21 and MTB3 were prioritized as candidate genes for further functional validation. Our findings identified qBr10 as a strong candidate for cloning and offer closely associated markers to aid in marker-assisted improvement of branching and capitulum number in sunflower breeding. Full article

Sunflower (Helianthus annuus L.) production is severely hindered by continuous cropping obstacles, leading to soil degradation and significant yield declines. This study compared soybean–sunflower (G-H) and maize–sunflower (Z-H) rotations against sunflower monoculture (H-H) to elucidate the mechanisms of soil health restoration associated with crop rotation. Our results demonstrated that Z-H and G-H rotations led to a profound yield increase of 103.19% and 82.35%, respectively, with Z-H improving the 100-grain weight by 52.63%. Soil biological revitalization was evidenced by a 98.29% increase in sucrase activity and a 28.92% rise in alkaline phosphatase activity. Metagenomic analysis revealed that the rotation sequences increased bacterial Chao1 richness by 35.29% and fungal Shannon diversity by 20.17%. Specifically, the rotation treatments proactively recruited beneficial taxa such as Pontibacter (Log₂FC > 3.0) and Panaeolus (Log₂FC = 6.88), while effectively suppressing pathogens such as Ceratobasidiaceae. Co-occurrence network analysis identified a complex bacterial scaffold (199 nodes, 53 modules) that provided greater structural robustness than the fungal network (27 nodes). It is concluded that diversified rotations effectively mitigate continuous cropping obstacles by reactivating nutrient cycling and restructuring the rhizosphere into a stable, modular microbial interactome. This study provides a quantitative framework for utilizing biological strategies to restore soil health in degraded agroecosystems. Full article