Parasitic Plants Research Articles

Multi-omics approaches define novel aphid effector candidates associated with virulence and avirulence phenotypes

Abstract Background Compatibility between plant parasites and their hosts is genetically determined {Citation}both interacting organisms. For example, plants may carry resistance (R) genes or deploy chemical defences. Aphid saliva contains many proteins that are secreted into host tissues. Subsets of these proteins are predicted to act as effectors, either subverting or triggering host immunity. However, associating particular effectors with virulence or avirulence outcomes presents challenges due to the combinatorial complexity. Here we use defined aphid and host genetics to test for co-segregation of expressed aphid transcripts and proteins with virulent or avirulent phenotypes. Results We compared virulent and avirulent pea aphid parental genotypes, and their bulk segregant F1 progeny on Medicago truncatula genotypes carrying or lacking the RAP1 (Resistance to Acyrthosiphon pisum 1) resistance quantitative trait locus. Differential gene expression analysis of whole body and head samples, in combination with proteomics of saliva and salivary glands, enabled us to pinpoint proteins associated with virulence or avirulence phenotypes. There was relatively little impact of host genotype, whereas large numbers of transcripts and proteins were differentially expressed between parental aphids, likely a reflection of their classification as divergent biotypes within the pea aphid species complex. Many fewer transcripts intersected with the equivalent differential expression patterns in the bulked F1 progeny, providing an effective filter for removing genomic background effects. Overall, there were more upregulated genes detected in the F1 avirulent dataset compared with the virulent one. Some genes were differentially expressed both in the transcriptome and in the proteome datasets, with aminopeptidase N proteins being the most frequent differentially expressed family. In addition, a substantial proportion (27%) of salivary proteins lack annotations, suggesting that many novel functions remain to be discovered. Conclusions Especially when combined with tightly controlled genetics of both insect and host plant, multi-omics approaches are powerful tools for revealing and filtering candidate lists down to plausible genes for further functional analysis as putative aphid effectors.

Refining dual RNA-seq mapping: sequential and combined approaches in host-parasitic plant dynamics

Transcriptional profiling in host plant-parasitic plant interactions is challenging due to the tight interface between host and parasitic plants and the percentage of homologous sequences shared. Dual RNA-seq offers a solution by enabling in silico separation of mixed transcripts from the interface region. However, it has to deal with issues related to multiple mapping and cross-mapping of reads in host and parasite genomes, particularly as evolutionary divergence decreases. In this paper, we evaluated the feasibility of this technique by simulating interactions between parasitic and host plants and refining the mapping process. More specifically, we merged host plant with parasitic plant transcriptomes and compared two alignment approaches: sequential mapping of reads to the two separate reference genomes and combined mapping of reads to a single concatenated genome. We considered Cuscuta campestris as parasitic plant and two host plants of interest such as Arabidopsis thaliana and Solanum lycopersicum. Both tested approaches achieved a mapping rate of ~90%, with only about 1% of cross-mapping reads. This suggests the effectiveness of the method in accurately separating mixed transcripts in silico. The combined approach proved slightly more accurate and less time consuming than the sequential approach. The evolutionary distance between parasitic and host plants did not significantly impact the accuracy of read assignment to their respective genomes since enough polymorphisms were present to ensure reliable differentiation. This study demonstrates the reliability of dual RNA-seq for studying host-parasite interactions within the same taxonomic kingdom, paving the way for further research into the key genes involved in plant parasitism.

Secretory Proteins Are Involved in the Parasitism of Melon by Phelipanche aegyptiaca During the Attachment Stage

Parasitic plants represent a significant challenge in global agriculture, with Broomrape (Orobanche/Phelipanche spp.) being a notable example of a holoparasitic species that targets the roots of host plants. This study employed comparative transcriptomics to investigate the mechanisms underlying the parasitism of P. aegyptiaca on melon, focusing on both resistant and susceptible interactions. The findings indicate that the critical phase of P. aegyptiaca parasitism occurs during the post-attachment stage. It is suggested that peptidases may play a role in the development of invasive cells, while cell wall-degrading enzymes (CWDEs) are likely involved in cell wall modification and degradation, and transferases, elicitors, and effectors may play a role in immune regulation. In this study, 25 tobacco rattle virus (TRV) recombinant vectors were successfully constructed and functionally validated using a host-induced gene silencing assay to explore the functions of candidate-secreted effector proteins. The results revealed that silencing Cluster-107894.0, Cluster-11592.0, and Cluster-12482.0 significantly decreased the parasitism rate of P. aegyptiaca on Nicotiana benthamiana. Notably, Cluster-107849.0 encodes a cellulase with hydrolase activity, Cluster-11592.0 encodes a periodic-dependent kinase inhibitor with phosphoprotein activity, and Cluster-12482.0 encodes a glucan 1,3-β-glucosidase with hydrolase activity. These findings potentially offer a novel theoretical framework and justification for understanding host–parasite plant interactions, and suggest new avenues for developing crop varieties resistant to parasitic infestation.

Inhibition of the Germination of Root Parasitic Plants by Zeolitic Imidazolate Framework-8.

Crystalline ZIF-8 (C-ZIF-8) and amorphous ZIF-8 (Am-ZIF-8) were prepared and investigated to control the germination of Striga hermonthica, a root parasitic plant, which threatens cereal crops production particularly in sub-Saharan Africa. We have demonstrated that Am-ZIF-8 shows a better performance than C-ZIF-8 in inhibiting Striga seeds germination. This efficient performance of Am-ZIF-8 materials can be attributed to the incomplete deprotonation of 2 methylimidazole (2MIM) during amorphization, leading to the presence of unsaturated Zn-N coordination with the uncoordinated -NH groups available to undergo hydrogen bonding with the strigolactone analog GR24 forming a more stable Am-ZIF-8⋅⋅⋅GR24 hydrogen bonded network. We further established that application of ZIF-8 materials generally has no adverse effects on the growth and quality of rice crops.

Phylogenetic Study of Several Parasitic Plant Species Based on The atp-1 Gene Sequence

The distinction between parasitic and non-parasitic plants can be determined by analyzing the atp-1 gene, which plays a vital role in respiration and is known for its high mutation rate. This study analyzed the kinship of parasitic plant subclass species through the construction of a phylogenetic tree based on atp-1 gene sequences. The atp-1 gene sequences of parasitic and non-parasitic plants with a total of 29 species were obtained from NCBI. The sequences were then aligned with ClustalW and analyzed for mutation patterns. Sequences that have been aligned, phylogenetic trees were made with MEGA11 software with the Maximum Likelihood method and analyzed using the iTOL website. The sequences were analyzed for similarity and kinship with Matrix Coefficient and Haplotype Construction. The atp-1 gene proved that parasitic plants (hemiparasites) are furthermore related to non-parasitic plants compared to holoparasite parasitic plants. Besides that, the kinship of parasitic plants can be analyzed by several methods, namely matrix coefficient to measure similarity, DnaSP to analyzing haplotype, and haplotype network to find out detailed information on mutations that occur. Matrix coefficients can also be used to measure specific similarities between species. It was found that the same subclass had high similarities, for example the species Santalum album and Heisteria parvifolia with a genetic distance value of 0.00574. Meanwhile, different subclasses have low similarity, such as Cassytha filiformis and Ombrophytum with a genetic distance value of 0.07871. This study shows that the atp-1 gene is effective in analyzing the kinship between parasitic and non-parasitic plants. Hemiparasites are genetically closer to non-parasitic plants than holoparasites, with higher genetic similarity within the same subclass.

Parasitic plants show striking convergence in host preference across angiosperm lineages.

The host specificity of a parasite underpins its ecology, distribution, invasive potential and adaptability, yet for most parasitic plants host ranges are poorly understood. We examine host-parasite relationships across lineages to infer how host specificity may have influenced the evolution of parasitism in plants. Host preference data for all plant holoparasite species were manually collected from literature and herbarium specimens, then analysed to investigate and visualise host diversity and specificity. We reveal a disproportionality in host preference across host lineages: the Asteraceae contains 10% of angiosperm diversity but is infected by 31% of parasite species; meanwhile Monocots comprise 23% but are infected by just 3.2%. Furthermore, we observe striking convergence in host preference: Asteraceae, Euphorbiaceae and Fabaceae are infected by six, five and four independent parasite lineages, respectively. We also demonstrate considerable variation in the degree of host specificity among closely related parasite species; a result that does not reflect the expectation of holoparasites - especially endoparasites - as host specialists. The marked pattern of convergence in preference across disparate lineages points to a common pathway in the evolution of parasitism of eudicots in preference to monocots, which may have in turn have been driven by a divergence in host root and vascular architecture. The unexpected variation in host specificity among closely related species suggests that even apparent generalists may comprise cryptic host-specific taxa. This highlights the value of host preference as an additional consideration in parasitic plant taxonomy. Together, our data point to a complex interplay between ecological and physiological factors driving the evolution of host-parasite interactions. Moreover, they emphasize how little is known about the ecology of most holoparasitic plants, a group of organisms that are especially vulnerable at a time of unprecedented biodiversity loss and extinction.

Timing of Plant Extracts Application in the Management of Meloidogyne incognita on Tomato Plants

Meloidogyne incognita, a widespread and damaging plant parasite, reduces crop yields. Chemical treatments are common but pose health and environmental risks, leading to a search for safer alternatives. Plant extracts with secondary metabolites, like those from Maerua angolensis and Tabernaemontana elegans, show promise for nematode control, though their efficacies vary. This study aimed to investigate how the timing of applying T. elegans and M. angolensis extracts influenced the population densities of M. incognita and the growth of tomato (Solanum lycopersicon L.) plants. The experiment was a factorial design with two plant extracts applied at 5 g per plant and three different timings of application relative to nematode inoculation. Additionally, the experiment included positive (chemical standard (Nemacur® 10 GR)) and negative (plants inoculated with nematodes only) controls, alongside naturally grown plants. The results indicate that applying plant extracts before the nematode inoculation or simultaneously with the inoculation reduced the total nematode populations as effectively as the Nemacur positive control. Plants treated with extracts showed improved growth variables compared with those treated with Nemacur® and the natural growing conditions. In conclusion, applying plant extracts before or simultaneously with nematode inoculation effectively suppressed the nematodes and enhanced the plant growth variables. These findings suggest that such plant extracts could be adopted as part of integrated nematode management strategies in agricultural settings.

HTL/KAI2 signaling substitutes for light to control plant germination.

Plants monitor multiple environmental cues, such as light and temperature, to ensure they germinate at the right time and place. Some specialist plants, like ephemeral fire-following weeds and root parasitic plants, germinate primarily in response to small molecules found in specific environments. Although these species come from distinct clades, they use the same HYPOSENSITIVE TO LIGHT/KARRIKIN INSENSITIVE 2 (HTL/KAI2) signaling pathway, to perceive different small molecules suggesting convergent evolution on this pathway. Here, we show that HTL/KAI2 signaling in Arabidopsis thaliana bypasses the light requirement for germination. The HTL/KAI2 downstream component, SUPPRESSOR OF MAX2 1 (SMAX1) accumulates in the dark and is necessary for PHYTOCHROME INTERACTING FACTOR 1/PHYTOCHROME INTERACTING FACTOR 3-LIKE 5 (PIF1/PIL5) to regulate hormone response pathways conducive to germination. The interaction of HTL/KAI2 and light signaling may help to explain how specialist plants like ephemeral and parasitic weeds evolved their germination behaviour in response to specific environments.

Mitochondrial Splicing Efficiency Is Lower in Holoparasites Than in Free-Living Plants

Abstract Mitochondria play a crucial role in eukaryotic organisms, housing their own genome with genes vital for oxidative phosphorylation. Coordination between nuclear and mitochondrial genomes is pivotal for organelle gene expression. Splicing, editing and processing of mitochondrial transcripts are regulated by nuclear-encoded factors. Splicing efficiency (SEf) of the many group II introns present in plant mitochondrial genes is critical for mitochondrial function since a splicing defect or splicing deficiency can severely impact plant growth and development. This study investigates SEf in free-living and holoparasitic plants, focusing on 25 group II introns from 15 angiosperm species. Our comparative analyses reveal distinctive splicing patterns with holoparasites exhibiting significantly lower SEf, potentially linked to their unique evolutionary trajectory. Given the preponderance of horizontal gene transfer (HGT) in parasitic plants, we investigated the effect of HGT on SEf, such as the presence of foreign introns or foreign nuclear-encoded splicing factors. Contrary to expectations, the SEf reductions do not correlate with HGT events, suggesting that other factors are at play, such as the loss of photosynthesis or the transition to a holoparasitic lifestyle. The findings of this study broaden our understanding of the molecular evolution in parasitic plants and shed light on the multifaceted factors influencing organelle gene expression.

Occurrence and effect of dwarf mistletoe (Arceuthobium globosum and A. vaginatum) in high-elevation forests in México

Climate change has very important effects on high mountain forests (>3500 masl), which face various ecological problems associated with global change including the proliferation of pests and parasitic plants. These sensitive ecological systems cover approximately 39,000 ha of Mexican territory and occur around some of the highest volcanoes in the country. The objective of this research was to determine the spatial distribution and infestation levels of dwarf mistletoe (Arceuthobium spp.) in the main populations of Pinus hartwegii in five mountains of the Trans-Mexican Volcanic System (Pico de Orizaba, Nevado de Toluca, Cofre de Perote, Nevado de Colima and Monte Tláloc) and identify infestation patterns in relation to the structure of the forest. In the study, 2658 sampling sites (1000 m² each) were installed using the contour lines as access transects to the forest, distributed at every 100 of altitude, between 3500 and 4000 masl. Approximately 32 % of the sampled area had some level of attack by dwarf mistletoe, distributed across all diameter categories of the trees. The infestations affected the establishment of natural regeneration and rates of tree mortality.

Continuous cropping obstacles: Insights from the community composition and the imbalance carbon fluxes within soil nematode food web

Long-term continuouscroppingcan lead to the deterioration of soil environment and the decrease of soil productivity. However, the biological mechanism on the negative effects of long-term continuous cropping has not been extensively explored. Soil nematode food web with multiple trophic levels play critical roles in nutrient cycling and energy flowing in the agroecosystem. Quantifying the carbon flux through different trophic channels within the nematode food web can indicate how continuous cropping influences carbon cycling in the agroecosystem by altering soil biota communities. Therefore, the effects of continuous peanut cropping with different years (1, 5, 20, and 30 years) on soil properties, soil nematode community composition, carbon flux within nematode food web and crop yields were investigated. Results showed that soil pH significantly decreased with increasing continuous cropping years. Differently, soil organic carbon and total nitrogen were the highest in 20-year, and decreased in 30-year of continuous cropping. As continuous cropping years increased, the relative abundance of microbivorous nematodes decreased and that of plant parasites reached as high as 76.11 % and 68.22 % in 20- and 30-year, respectively. Pearson correlation analysis revealed the nematode diversity, the carbon flux uniformity and peanut yield had a significant negative correlation with continuous cropping years. The random forest model indicated that the soil pH and the relative abundance of plant parasites were the key influence factor of the carbon flux uniformity within soil nematode food web. Outbreaks of plant parasites lead to the disruption of carbon flux uniformity within soil nematode food web, which can increase the risk of peanut yield decline after long-term continuous cropping. In conclusion, continuous peanut cropping changed soil properties, reduced soil nematode diversity, and disturbed the multitrophic carbon flux complementarity and uniformity in soil nematode food web, ultimately limiting the crop productivity. This study enhances our understanding of the importance of the resource transfers among soil food web in maintaining sustainable agroecosystem productivity.

Global analysis of neuropeptide receptor conservation across phylum Nematoda.

The phylum Nematoda is incredibly diverse and includes many parasites of humans, livestock, and plants. Peptide-activated G protein-coupled receptors (GPCRs) are central to the regulation of physiology and numerous behaviors, and they represent appealing pharmacological targets for parasite control. Efforts are ongoing to characterize the functions and define the ligands of nematode GPCRs, with already most peptide GPCRs known or predicted in Caenorhabditis elegans. However, comparative analyses of peptide GPCR conservation between C. elegans and other nematode species are limited, and many nematode GPCRs remain orphan. A phylum-wide perspective on peptide GPCR profiles will benefit functional and applied studies of nematode peptide GPCRs. We constructed a pan-phylum resource of C. elegans peptide GPCR orthologs in 125 nematode species using a semi-automated pipeline for analysis of predicted proteome datasets. The peptide GPCR profile varies between nematode species of different phylogenetic clades and multiple C. elegans peptide GPCRs have orthologs across the phylum Nematoda. We identified peptide ligands for two highly conserved orphan receptors, NPR-9 and NPR-16, that belong to the bilaterian galanin/allatostatin A (Gal/AstA) and somatostatin/allatostatin C (SST/AstC) receptor families. The AstA-like NLP-1 peptides activate NPR-9 in cultured cells and are cognate ligands of this receptor in vivo. In addition, we discovered an AstC-type peptide, NLP-99, that activates the AstC-type receptor NPR-16. In our pan-phylum resource, the phylum-wide representation of NPR-9 and NPR-16 resembles that of their cognate ligands more than those of allatostatin-like peptides that do not activate these receptors. The repertoire of C. elegans peptide GPCR orthologs varies across phylogenetic clades and several peptide GPCRs show broad conservation in the phylum Nematoda. Our work functionally characterizes the conserved receptors NPR-9 and NPR-16 as the respective GPCRs for the AstA-like NLP-1 peptides and the AstC-related peptide NLP-99. NLP-1 and NLP-99 are widely conserved in nematodes and their representation matches that of their receptor in most species. These findings demonstrate the conservation of a functional Gal/AstA and SST/AstC signaling system in nematodes. Our dataset of C. elegans peptide GPCR orthologs also lays a foundation for further functional studies of peptide GPCRs in the widely diverse nematode phylum.

Agrobacterium-mediated Cuscuta campestris transformation as a tool for understanding plant-plant interactions.

Cuscuta campestris, a stem parasitic plant, has served as a valuable model plant for the exploration of plant-plant interactions and molecular trafficking. However, a major barrier to C. campestris research is that a method to generate stable transgenic plants has not yet been developed. Here, we describe the development of a Cuscuta transformation protocol using various reporter genes (GFP, GUS, or RUBY) and morphogenic genes (CcWUS2 and CcGRF/GIF), leading to a robust protocol for Agrobacterium-mediated C. campestris transformation. The stably transformed and regenerated RUBY C. campestris plants produced haustoria, the signature organ of parasitic plants, and these were functional in forming host attachments. The locations of T-DNA integration in the parasite genome were confirmed through TAIL-PCR. Transformed C. campestris also produced flowers and viable transgenic seeds exhibiting betalain pigment, providing proof of germline transmission of the RUBY transgene. Furthermore, RUBY is not only a useful selectable marker for the Agrobacterium-mediated transformation, but may also provide insight into the movement of molecules from C. campestris to the host during parasitism. Thus, the protocol for transformation of C. campestris reported here overcomes a major obstacle to Cuscuta research and opens new possibilities for studying parasitic plants and their interactions with hosts.

A Parasite Plant Promotes the Coexistence of Two Annual Plants.

Consumers can influence the competitive outcomes of prey species in various ways. Modern coexistence theory predicts that consumers can promote prey coexistence by preferably targeting a competitively superior one, thereby reducing fitness differences. However, previous studies yielded mixed conclusions. In this study, we tested the hypothesis that a parasitic annual plant, Cuscuta campestris, facilitates the coexistence of two common annual plants. We performed field surveys and parasitism experiments to parameterize a plant competition dynamics model. The model suggested a competition-defence tradeoff: the legume Lespedeza striata was a better competitor than the grass Setaria faberi, while it was more susceptible to the parasite. Moreover, an empirical host-parasite dynamics model, extended from the plant competition model, predicted their coexistence within broad, biologically reasonable ranges of parameters. This work provides field evidence of the coexisting-promoting role of a parasitic plant, as caused by stabilising feedback between host and parasite densities.

Pseudomonas produce various metabolites displaying herbicide activity against broomrape

Pseudomonads are well-known for their plant growth-promoting properties and biocontrol capabilities against microbial pathogens. Recently, their potential to protect crops from parasitic plants has garnered attention. This study investigates the potential of different Pseudomonas strains to inhibit broomrape growth and to protect host plants against weed infestation.Four Pseudomonas strains, two P. fluorescens JV391D17 and JV391D10, one P. chlororaphis JV395B and one P. ogarae F113 were cultivated using various carbon sources, including fructose, pyruvate, fumarate, and malate, to enhance the diversity of potential Orobanche growth inhibition (OGI)-specialized metabolites produced by Pseudomonas strains. Both global and targeted metabolomic approaches were utilized to identify specific OGI metabolites.Both carbon sources and Pseudomonas genetic diversity significantly influenced the production of OGI metabolites. P. chlororaphis JV395B and P. ogarae F113 produced unique OGI metabolites belonging to different chemical families, such as hydroxyphenazines and phloroglucinol compounds, respectively. Additionally, metabolomic analyses identified an unannotated potential OGI ion, M375T65. This ion was produced by all Pseudomonas strains but was found to be over-accumulated in JV395B, which likely explains its superior OGI activity. Then, greenhouse experiments were performed to evaluate the biocontrol efficacy of selected strains: they showed the efficacy of these strains, particularly JV395B, in reducing broomrape infestation in rapeseed.These findings suggest that certain Pseudomonas strains, through their metabolite production, can offer a sustainable biocontrol strategy against parasitic plants. This biocontrol activity can be optimized by environmental factors, such as carbon amendments. Ultimately, this approach presents a promising alternative to chemical herbicides.

Host-driven phenotypic and phenological differentiation in sympatric races of a parasitic plant

Host specificity is a key factor influencing the ecology and evolutionary diversification of parasitic organisms. Host specialisation and geographic isolation are known to lead to the genetic differentiation of allopatric races in parasitic plants. However, how divergence can co-occur in sympatry remains largely unknown. We investigated phenological and phenotypic differentiation and potential reproductive isolation among three sympatric genetic races of Cytinus hypocistis (Cytinaceae) - an extreme endophytic holoparasite with a high degree of host specialisation. We compared spatio-temporal variations in flowering phenology, flower production, floral longevity, floral rewards, and morphology, and conducted inter-race pollinations among three races parasitising Cistus ladanifer, C. salviifolius, and Halimium halimifolium (Cistaceae) in six co-occurring populations. We found that host-defined genetic races differed significantly across multiple phenotypic and phenological aspects – a phenomenon previously overlooked due to the plants’ cryptic morphology. The race parasitising H. halimifolium showed earlier blooming, higher floral display, longer flowers, and higher pollen production and nectar concentration; the race on C. salviifolius showed later flowering, significantly lower floral display and smaller flowers with lower floral rewards; the race on C. ladanifer had intermediate characteristics. Genetic races were interfertile yet may remain differentiated by restricted gene flow and host-driven selection pressures. Together, our data point to a rare case of sympatric divergent evolution hiding in plain sight: apparently morphologically similar co-occurring parasite races can be genetically, phenotypically, and phenologically distinct. This hitherto unreported example of host-driven sympatric diversification challenges how species concepts are applied to cryptic parasitic plant races.

Potential Plant-To-Plant Transmission: Shared Endophytic Bacterial Community Between Ziziphus lotus and Its Parasite Cuscuta epithymum

Microbiota associated with host–parasite relationships offer an opportunity to explore interactions among plants, parasites, and microbes, thereby contributing to the overall complexity of community structures. The dynamics of ecological interactions between parasitic plants and their hosts in arid environments remain largely understudied, especially in Africa. This study aimed to examine the bacterial communities of Cuscuta epithymum L. (clover dodder), an epiphytic parasitic plant, and its host, Ziziphus lotus L. (jujuba), in an arid environment. Our goal was to uncover the ecological complexities of microbial communities within the framework of plant–plant interactions. We conducted a comprehensive analysis of the bacterial composition and diversity within populations of the C. epithymum parasite, the infected- and non-infected jujuba host, and their interface at the shoots of the host. This involved amplicon sequencing, targeting the V5–V6 regions of the 16S rRNA gene. A total of 5680 amplicon sequence variants (ASVs) were identified, with Pseudomonadota, Bacillota, and Actinobacteriota being prevalent phyla. Among the bacterial communities, three genera were dominant: Cutibacterium, Staphylococcus, and Acinetobacter. Interestingly, analyses of alpha-diversity (p = 0.3 for Shannon index and p = 0.5 for Simplon index) and beta-diversity (PERMANOVA, with p-values of 0.6 and 0.3) revealed no significant differences between Cuscuta-infected and non-infected jujube shrubs, suggesting a shared shoot endophytic bacteriome. This finding advances our comprehension of microbial communities linked to plant–parasite interactions in the arid environments of Africa. Further research on various hosts is required to confirm plant-to-plant bacterial transmission through Cuscuta infection. Additionally, studies on functional diversity, cytology, ecophysiology and the mechanisms by which bacterial communities transferred between host and parasite are necessary.

Physiological and biochemical attributes of the association host-parasite Tamarix aphylla-Plicosepalus acacia

Parasitic plants have been viewed as pests since they are able to damage agricultural crops and forest trees. They establish vasculature connections with the hosts and withdraw the required nutritive resources. This study aimed to explore the physiological and biochemical effects of the parasitic plant Plicosepalus acacia on the host Tamarix aphylla. It was conducted on young fully expanded leaves from the uninfected and infected trees and the parasitic plant ‘in situ’. The parasite had higher net photosynthetic assimilation rate (A), transpiration rate (E) and stomatal conductance (gs) compared to the host. Equally, it had two-fold greater water potential (Ψ) and osmotic potential (Ψs). It accumulated high amount of K, while it avoided accumulation of the most trace and ultratrace elements. Otherwise, parasitism seemed to increase A, WUE, water uptake and accumulation of the most major, trace and ultra-trace elements, however it reduced the accumulation of osmolytes at the infected plants. Based on UPLC-MS approach, P. acacia seemed to use a group of composites to interact with the host, including oleamide as a protector metabolite against host's defense system, carvone to establish vasculature connections with the host, cuminaldehyde to weaken growth and proliferation of the host, and caprolactam to weaken the distal part of the host. In contrast, the host T. aphylla could be used pipecolinic acid and nicotinamide to regulate systemic resistance and to defense against the parasite infection. Finally, despite the defense molecular interactions between the two partners, the parasitic plant exhibited several beneficial effects on the host.

Extraction of Flavonoids from Parasitic plant Macrosolen cochinchinensis using Ultrasound-Assisted Extraction: An Optimization Approach

The parasitic plant Macrosolen cochinchinensis (Lour.) VAN Tiegh, commonly found parasitizing mango trees, contains flavonoid compounds with potential anticancer properties. This study aims to optimize the extraction of flavonoids from M. cochinchinensis using the Ultrasonic Assisted Extraction (UAE) method. Three extraction parameters were investigated to determine the best conditions for maximizing extract yield and flavonoid concentration. The parameters considered for the UAE technique were different ethanol concentrations (30%, 70%, and 96%), extraction times (15, 30, and 45 minutes), and solvent-to-sample ratios (1:10, 1:20, and 1:30). The study used Response Surface Methodology (RSM) to identify the optimal extraction conditions. The analysis using RSM indicated that the highest extraction yield (10%) was achieved with a sample-to-solvent ratio of 1:30, 30% ethanol concentration, and an extraction time of 45 minutes. The highest flavonoid content (457.96 mg QE/g extract) was obtained with a solid-to-liquid ratio between 1:20 and 1:30, using 65 to 80% ethanol solvent and an extraction time of 45 minutes. These results suggest that these parameters extract flavonoid compounds from M. cochinchinensis leaves.

Sunflower broomrape (Orobanche cumana Wallr.) damage in different hybrids of Helianthus annuus

Aim. To study the racial composition of broomrape in sunflower crops in the conditions of the Forest-Steppe and Polissya of Ukraine. Methods. Sunflower hybrids were evaluated for resistance to broomrape in soil culture using a modified method and the roll method of seed germination. Results. The results of the study revealed a different reaction of sunflower hybrids to the parasite. Sunflower hybrids Arizona, Transol, Bosphorus, resistant to race F, were moderately affected by broomrape. On average, there were 5 to 6 nodules of the parasite per sunflower plant. Sunflower hybrids Estrada, Kupava, Kadiks, Laskala, resistant to race G, were affected to a weak extent by broomrape. On average, there were 2-3 nodules of the parasite per sunflower plant. No sunflower hybrids with complete immunity to broomrape were found. Based on the research, the reasons for the widespread spread of broomrape in the fields in the central, northern and western regions of the country were identified. Conclusions. The emergence of new very aggressive races of broomrape (E, F and G) indicates an important need to solve the problem of creating breeding material resistant to new races of this parasitic plant. The intensive accumulation of the parasite races E, F and G in sunflower crops is associated with the violation of crop rotations and saturation of fields with hybrids of this crop, which are mainly resistant to races 5 (E) and 6 (F) of the parasite.