Parasitic Plants Research Articles

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.

Gene silencing in broomrapes and other parasitic plants of the Orobanchaceae family: mechanisms, considerations, and future directions.

Holoparasites of the Orobanchaceae family are devastating pests causing severe damage to many crop species and are nearly impossible to control with conventional methods. During past decades RNA interference (RNAi) has been seen as a promising approach to control various crop pests. The exchange of small RNAs (sRNAs) between crops and parasitic plants has been documented indicating a potential for the development of methods to protect them via the delivery of the sRNAs to parasites, called host-induced gene silencing (HIGS). Here we describe various approaches used for gene silencing in plants and suggest solutions to improve the long-distance movement of the silencing triggers to elevate the HIGS efficiency in parasitic plants. We also investigate the important biological processes during parasites life cycle with a focus on broomrape species, providing several appropriate target genes that can be used in, especially, multiplex gene silencing experiments. We also touch on how the application of nanoparticles can improve the stability and delivery of the silencing triggers, highlighting its potential for parasitic plants control. Finally, suggestions for further research and possible directions for RNAi in parasitic plants are provided.

Highly sensitive strigolactone perception by a divergent clade KAI2 receptor in a facultative root parasitic plant, Phtheirospermum japonicum.

Phtheirospermum japonicum, a member of the Orobanchaceae family, is a facultative root parasitic plant that can survive without parasitizing the host. In contrast, obligate root parasitic plants such as Striga and Orobanche, which are also members of the Orobanchaceae family, cannot survive in the absence of the host. The germination of obligate root parasitic plants is typically induced by host root-derived strigolactones (SLs) at very low concentrations. The KAI2/HTL family proteins have been found to be involved in the perception of karrikin (KAR), a smoke-derived germination inducer and unidentified endogenous ligand, in non-parasitic plants. Obligate root parasitic plants possess uniquely diverged KAI2 clade genes, which are collectively referred to as KAI2d. Many of those have been shown to function as SL receptors. Intriguingly, the KAI2d clade genes are also conserved in P. japonicum, even though this plant does not require SLs for germination. The biochemical and physiological functions of the KAI2d proteins in P. japonicum remain unclear. Here, we report that some of these proteins can function as SL receptors in P. japonicum. Moreover, we found that one of them, PjKAI2d4, is highly sensitive to SLs when expressed in Arabidopsis, and it is similar to the sensitive SL receptors found in Striga and Orobanche. These results suggest that the KAI2d clade SL receptors play a crucial role not only in obligate parasites but also in facultative parasitic plants.

Dominant-negative KAI2d paralogs putatively attenuate strigolactone responses in root parasitic plants.

Many root parasitic plants in the Orobanchaceae use host-derived strigolactones as germination cues. This adaptation facilitates attachment to a host and is particularly important for the success of obligate parasitic weeds that cause substantial crop losses globally. Parasite seeds sense strigolactones through "divergent" KARRIKIN INSENSITIVE2 (KAI2d)/HYPOSENSITIVE TO LIGHT (HTL) α/β-hydrolases that have undergone substantial duplication and diversification in Orobanchaceae genomes. After germination, chemotropic growth of parasite roots toward a strigolactone source also occurs in some species. We investigated which of the seven KAI2d genes found in a facultative hemiparasite, Phtheirospermum japonicum, may enable chemotropic responses to strigolactones. To do so, we developed a triple mutant Nbd14a,b kai2i line of Nicotiana benthamiana in which strigolactone-induced degradation of SMAX1, an immediate downstream target of KAI2 signaling, is disrupted. In combination with a transiently expressed, ratiometric reporter of SMAX1 protein abundance, this mutant forms a system for the functional analysis of parasite KAI2d proteins in a plant cellular context. Using this system, we unexpectedly found three PjKAI2d proteins that do not trigger SMAX1 degradation in the presence of strigolactones. Instead, these PjKAI2d inhibit the perception of low strigolactone concentrations by strigolactone-responsive PjKAI2d in a dominant-negative manner that depends upon an active catalytic triad. Similar dominant-negative KAI2d paralogs were identified in an obligate hemiparasitic weed, Striga hermonthica. These proteins suggest a mechanism for attenuating strigolactone signaling in parasites, which might be used to enhance the perception of shallow strigolactone gradients during root growth toward a host or to restrict germination responses to specific strigolactones.

The Use of Caenorhabditis elegans as a Model for Plant-Parasitic Nematodes: What Have We Learned?

Nematoda is a diverse phylum that is estimated to contain more than a million species. More than 4,100 of these species have the ability to parasitize plants and cause agricultural losses estimated at US $173 billion annually. This has led to considerable research into their biology to minimize crop losses via control methods. At the infancy of plant-parasitic nematode molecular biology, researchers compared nematode genomes, genes, and biological processes to the model nematode species Caenorhabditis elegans, which is a free-living bacterial feeder. This well-annotated and researched model nematode assisted the molecular biology research, e.g., with genome assemblies, of plant-parasitic nematodes. However, as research into these plant parasites progressed, the necessity of relying on the free-living relative as a reference has reduced. This is partly driven by revealing the considerable divergence between the two types of nematodes both genomically and anatomically, forcing comparisons to be redundant as well as the increased quality of molecular plant nematology proposing more suitable model organisms for this clade of nematode. The major irregularity between the two types of nematodes is the unique anatomical structure and effector repertoire that plant nematodes utilize to establish parasitism, which C. elegans lacks, therefore reducing its value as a heterologous system to investigate parasitic processes. Despite this, C. elegans remains useful for investigating conserved genes via its utility as an expression system because of the current inability to transform plant-parasitic nematodes. Unfortunately, owing to the expertise that this requires, it is not a common and/or accessible tool. Furthermore, we believe that the application of C. elegans as an expression system for plant nematodes will be redundant once tools are established for stable reverse-genetics in these plant parasites. This will remove the restraints on molecular plant nematology and allow it to excel on par with the capabilities of C. elegans research.

Parasitic plants regulate C and N distribution among common mycorrhizal networks linking host and neighboring plants.

Common mycorrhizal networks (CMNs) can link multiple plants and distribute nutrients among them. However, how parasitic plants regulate the carbon and nutrient exchange between CMNs and the linked plants is unknown. Thus, we conducted a container experiment with two Trifolium pratense grown in two plastic cores and connected only by CMNs using a 25-μm nylon fabric in each container. Host T. pratense was parasitized or not parasitized by Cuscuta gronovii. CMNs were left intact or broken by rotating the cores with the host or neighboring T. pratense. The dual 15N and 13C labeling method was used to evaluate the N distributed by CMNs to the host and neighboring T. pratense and the recently fixed C from the host and neighboring T. pratense to CMNs. The results showed that CMNs distributed more 15N to unparasitized neighboring T. pratense than the parasitized host T. pratense. Moreover, the unparasitized neighboring T. pratense provides more recently fixed C to CMNs than the parasitized host T. pratense. These results revealed that the parasite regulated C and nutrient exchange between CMNs and the linked plants following the reciprocal rewards rule. Moreover, this study highlights the importance of parasitic plants in the regulation of mutualistic interactions in ecological webs.

Deciphering anhydrobiosis and plant parasitism of the wheat seed gall nematode, Anguina tritici through transcriptomic analysis

The wheat seed gall nematode (Anguina tritici L.) poses a significant threat to wheat and barley production. Central to its survival is the ability to endure desiccation through anhydrobiosis, setting it apart from other nematodes. Unraveling the molecular mechanisms governing anhydrobiosis and plant parasitism in A. tritici is crucial for devising effective management strategies. A comprehensive transcriptomic analysis was conducted to elucidate the genetic pathways involved in these processes. Employing next-generation sequencing technologies, gene expression profiling was performed across three developmental stages, namely anhydrobiotic J2, revived J2 and the adult. Transcriptomic profiling yielded 139,002 transcripts in anhydrobiotic J2s, 156,731 in revived J2s, and 80,282 in adult stages, with a cumulative assembly size of 133.2 Mb. Differential gene expression analysis revealed that 1223 genes were significantly upregulated whereas 1934 genes were downregulated in anhydrobiotic J2s in comparison to revived J2s. Comparative transcriptomic analysis across nematode species highlighted conserved and species-specific genes. Functional annotation identified key genes associated with anhydrobiosis, plant parasitism, glycosylation, and longevity mechanisms. Real-time PCR validation corroborated differential expression patterns. The present study provides gene homologs and longevity pathways, which indicate similarity of the mechanism of dauer larva formation and survival strategies to that of Caenorhabditis elegans. Comprehensive understanding of the molecular basis for survival and parasitic strategies of A. tritici, shall provide potential targets for novel control interventions to mitigate nematode's impact on wheat crops.

Community ionomics reveals a diversity of mineral nutrition in a species‐rich shrubland on infertile soil

AbstractQuestionsHigh species richness is observed in certain shrublands on infertile substrates. Mineral nutrients are likely to be the primary limiting resources in these ecosystems, and below‐ground plant interactions may be crucial to understanding their diversity. Using ionomics, we investigated whether there were nutritional variations between plant species that coexist in a shrubland located in an edaphically extreme environment.LocationNew Caledonia.MethodsWe set up a 20 m × 20 m plot in a diverse shrubland (“maquis”) on ultramafic (infertile) substrate, in which we sampled all 475 plants taller than 1 m and characterized their ionome (22 elements).ResultsIn our study, 37 species were identified in the plot, representing all major forms of mycorrhizal symbioses, as well as nitrogen‐fixing plants, cluster rooted and parasitic plants. Notably, both nickel hyperaccumulating and manganese hyperaccumulating species were present. Hypervolume approaches were used to assess ionome overlap among the nine most abundant species, with the results revealing limited overlap. Moreover, it was observed that the rarest species in the plot also had the most functionally distinct features.ConclusionsDifferent nutritional strategies were present in the plot, as demonstrated by the variety of root symbioses and leaf ionomes. Our findings indicate coexistence of multiple species within this infertile shrubland may be achieved by species partitioning into different highly specialized biogeochemical niches.

Wild mungbean resistance to the nematode Meloidogyne enterolobii involves the induction of phenylpropanoid metabolism and lignification.

Root-knot nematodes (Meloidogyne spp.) are plant parasites causing annual economic losses amounting to several billion US dollars worldwide. One of the most aggressive species is M. enterolobii, a growing threat to agriculture due to its broad host range and ability to overcome many known resistance genes. Mungbean, a nutritionally and economically valuable crop, is particularly vulnerable to nematodes and pathogens. However, research focusing on mungbean resistance to M. enterolobii is scarce, and the corresponding defense mechanisms are poorly understood. Here, we screened mungbean accessions and identified an accession strongly resistant to M. enterolobii. Transcriptome analysis revealed 2730 differentially expressed genes (DEGs) in this resistant accession (CPI106939) compared to 1777 in the susceptible accession (Crystal) 7 days after nematode inoculation. The gene ontology (GO) upregulated in CPI106939 with functions related to plant-pathogen interactions, plant hormone signaling, oxidative stress, and plant immunity. Plant defense-related genes (WRKY, PAL, MAPK, POD and PR) were also significantly induced in CPI106939. Metabolome analysis showed that four secondary metabolites related to phenylpropanoid metabolism and lignification were significantly enriched in CPI106939. The induced immune response and secondary metabolites may underpin the enhanced resistance to M. enterolobii, providing insight into the resistance mechanisms in accession CPI106939 as well as candidate genes controlling the interaction between mungbean and its nematode parasite. Our study therefore provides foundations for the breeding of new varieties with intrinsic M. enterolobii resistance.

Parasitism by Cuscuta gronovii mediated soil legacy effects and the competitive ability of invasive and native plant species by changing soil abiotic and biotic properties

Parasitic plants can mediate soil conditioning by invasive and native host plant species, but how this may affect the competitive ability of these plants when they later grow in the conditioned soil has never been tested. This study tested whether soil conditioned by three invasive and three native plant species, either parasitized by a holoparasitic plant Cuscuta gronovii or non-parasitized, would differentially affect the competitive ability of those species. In the first phase, field soil was conditioned using individuals of the six host plant species, either parasitized or non-parasitized. The second phase tested the competitive ability of individuals of those invasive and native plants by growing them alone or in competition with Trifolium repens in either live or sterilized conditioned soil. In the soil conditioning phase, parasitism significantly increased soil NH4+-N concentration by 17 %, decreased soil organic carbon by 18 %, and marginally decreased microbial biomass carbon concentration by 21 %. In the soil feedback phase, native plant species generally had higher competitive ability in soil that was conditioned by parasitized plants than in soil that was conditioned by non-parasitized plants. In contrast, soil conditioned by parasitized plants had only a marginal effect on the competitve ability of invasive plants, compared to growth in soil conditioned by non-parasitized plants. Native plants had greater competitive ability in soil with lower soil organic carbon, while invasive plants had greater competitive ability in soil with higher microbial biomass carbon and lower NH4+-N. These findings demonstrate that parasitism by C. gronovii mediated different soil legacy effects of invasive and native plant species through changes in soil organic carbon, soil NH4+-N, and microbial biomass carbon levels. Broadly, these results suggest that parasitic plants may limit invasions by alien plant species and promote the co-existence of the invaders with native plant species through soil-mediated legacy effects.

Non-chemical management of fungal diseases in berries: A review

Abstract Organically grown berries are highly valued for their significant economic and nutritional benefits, playing a crucial role in fostering sustainable agriculture. However, meeting the escalating demand for organic berries while sustaining profitable yields of top-quality produce remains challenging, primarily due to the obstacles presented by plant diseases and significant insect pests acting as vectors. Globally, significant losses in organic berry agriculture stem from pathogenic organisms such as bacteria, viruses, fungi, oomycetes, nematodes, and parasitic plants. Although chemical pesticides have historically served as effective control measures, their high costs and potential environmental and health risks necessitate exploring alternative approaches. Consequently, there have been groundbreaking advancements in biological methods for disease management, driven by an enhanced understanding of the intricate interactions between plant pathogens and the plant immune system. This comprehensive analysis elucidates the common pests and diseases affecting organic berry crops, with particular emphasis on fungal pathogens posing the greatest risk. The review documents efficient management strategies to mitigate the harm caused by fungal infections, focusing on biological control using antagonistic microorganisms. Thanks to years of intensive research, numerous commercially available products showcasing the effectiveness of biological control in combating pathogenic threats in organic berry crops have emerged. Furthermore, our review provides insights into recent advancements in the diagnosis and detection of plant diseases, encompassing both time-tested approaches from the previous generations and important methods currently in use. Ultimately, this review aims to help organic berry growers implement successful eco-friendly management strategies to safeguard their crops and boost yields by offering an overview of the latest developments in disease management.

Native root hemiparasites form haustorial attachments with multiple invasive and expansive species

Parasitic plants are known for shaping plant communities, mainly by suppressing dominant species. This suppression, in some cases, fosters species coexistence and boosts overall diversity. Recent studies reveal that certain parasitic plants can curb invasive alien plants or expansive native species. In this study, we followed previous case studies, investigating the ability of three common Central European hemiparasitic species to attach to roots and form functional haustoria across a broad range of invasive and expansive hosts. For each host-hemiparasite pair, we posed two questions: (i) Do the hemiparasites produce haustoria on the host's roots or rhizomes? (ii) Does the anatomical structure of the haustoria include all features necessary for their functionality? We cultivated three hemiparasitic species, Melampyrum arvense L., Rhinanthus alectorolophus (Scop.) Pollich, and Odontites vernus subsp. serotinus (Dumort.) Corb., in pots with 18 candidate hosts. After cultivation, we dissected the root systems to determine haustoria abundance and to collect them for anatomical study to assess their functionality. Hemiparasite individuals in each pot were also counted. The hemiparasitic species produced haustoria on the majority of tested hosts (37 out of 44 combinations), with little difference between native expansive and alien invasive plant species. In 13 host-hemiparasite combinations (including eight combinations with invasive species), we identified abundant functional haustoria and good establishment of the hemiparasites. Remarkably, all three hemiparasitic species formed functional haustoria on invasive Asteraceae hosts. By contrast, Melampyrum arvense performed poorly when cultivated with grasses. We identified a series of hemiparasite-host combinations, which should be further tested for the potential hemiparasite effect on host fitness in the field. The abundance and anatomical structure of the haustoria indicates that the recognised low specificity of the hemiparasitic interactions applies also to associations with alien invasive species, with which they do not share a common evolutionary history.

Checklist of Parasitic Plants in Marilog District, Southern Philippines

Checklist of Parasitic Plants in Marilog District, Southern Philippines

The role of strigolactone structural diversity in the host specificity and control of Striga, a major constraint to sub‐Saharan agriculture

Social Impact StatementThe parasitic weed Striga affects crops such as sorghum, maize, millet, and rice in over 40 countries on the African continent and negatively impacts the livelihood of over 300 million small‐holder farmers. Striga seeds can remain dormant in the soil for many years until they are triggered to germinate by germination stimulants, called strigolactones, exuded from the roots of their host. Here, the current knowledge on the biosynthesis of the strigolactones, their structural diversity, and biological relevance are reviewed. This knowledge could improve Striga control and thus improve the livelihood of small‐holder farmers.SummaryThe parasitic plant genus Striga causes major yield losses to several crops such as sorghum, millet, and rice in arid and semi‐arid regions of the tropics. For Striga to successfully parasitize its host plant, two conditions should be fulfilled: suitable germination conditions and the presence of a host plant that exudes so‐called germination stimulants, strigolactones, that are also as a signal to attract beneficial micro‐organisms such as arbuscular mycorrhizal (AM) fungi. Different plant species exude qualitatively and quantitatively different blends of strigolactones, and this plays a key role in determining Striga host specificity. Sorghum lgs1 genotypes with a mutation in a sulfotransferase (SbSOT4A), for example, exude orobanchol and are resistant to Striga, while 5‐deoxystrigol is the major strigolactone exuded by susceptible cultivars with wild type SbSOT4A. In this review, we discuss the current knowledge on the biosynthesis of the large diversity of strigolactones, how SbSOT4A may be involved in this, and how strigolactone diversity may contribute to microbiome recruitment. Finally, we discuss how knowledge on the importance of strigolactone diversity can contribute to Striga control.

INCIDENCE AND SEVERITY OF DAMAGE AGENTS ON ESTABLISHED TREES IN URBAN GREEN AREAS

Trees in urban green areas (UGAs) face various stress-inducing factors that, together with the incidence and severity of damage agents, reduce their growth and health condition. The objective of this study was to characterize the incidence and severity of damage to trees located in 21 UGAs in the city of Texcoco, Mexico, as well as the relationship between their health, green area typology, and urban infrastructure. Using tree damage indicators, the incidence of two damage agents per tree was determined, and seven damage groups were identified: biotic agents, parasitic and epiphytic plants, insects, animals, abiotic agents, and anthropogenic factors. A damage severity index (DSI) was estimated at species level and by green area. Chlorophyll fluorescence was used to assess stress as an indirect measure of tree health condition in UGAs, and surrounding urban infrastructure was classified. A total of 1543 trees were assessed, and 23 damage agents were identified, affecting 9.95 % of the foliage, 10.24 % of the branches, 4.47 % of the trunk, and 0.45 % of the root collar and roots. As for incidence, 60.01 % showed no damage at all, 29.49 % showed only one agent, and 10.5 % showed two agents. Most of the trees at the UGAs were found to be under stress (≤ 0.78) and uncorrelated with DSI; however, the index was different by species and UGA (p ≤ 0.05). Insect damage and poor management practices were associated with the presence of buildings, busy roads, and people congregation areas inside UGAs.

Mistletoes benefit from initiating cascading effects in a cactus–stem borers–arthropods system: A positive feedback

Abstract Parasitic plants may indirectly modify arthropod community structure by inducing resistance/susceptibility in host plants. In the Atacama Desert, the mistletoe Tristerix aphyllus initiates cascading effects on its cactus host, Echinopsis chiloensis, inducing susceptibility to stem‐borer beetles, whose brood chambers are colonized by a diverse arthropod community. We evaluated whether those cascading effects initiated by Tristerix generate a positive or negative feedback loop on this parasitic plant. A positive or negative feedback loop would occur if the mistletoe‐elicited indirect effects on arthropod community result in increased or decreased mistletoe fitness, respectively. Specifically, by way of field sampling, experimental manipulation of number of brood chambers, and structural equation modelling, we assessed the indirect impact of number of brood chambers on Tristerix fitness mediated by its influence on the abundance of arthropod trophic guilds (omnivores, nectarivores, herbivores and predators). We found that the number of brood chambers had a positive indirect effect on mistletoe fitness, likely mediated by the increased abundance of nectarivores. The number of brood chambers was positively associated with the abundance of predators, nectarivores and herbivores. However, nectarivores were the only trophic guild showing a positive association with both number of brood chambers and Tristerix fitness. This positive feedback loop, together with the known pattern of specific disperser‐mediated cyclic reinfection of cacti by Tristerix, would indicate that mistletoe infection may ultimately threaten cactus survival.

Isolation of Haustorium Protoplasts Optimized by Orthogonal Design for Transient Gene Expression in Phelipanche aegyptiaca.

The efficient protoplast transient transformation system in plants is an important tool to study gene expression, metabolic pathways, and various mutagenic parameters, but it has not been established in Phelipanche aegyptiaca. As a root parasitic weed that endangers the growth of 29 species of plants in 12 families around the world, there is still no good control method for P. aegyptiaca. Even the parasitic mechanisms of P. aegyptiaca and the related genes regulating parasitism are not yet understood. In this study, by comparing the factors related to protoplast isolation and transfection, we developed the optimal protocol for protoplast isolation and transfection in Phelipanche aegyptiaca haustorium. The optimal protoplast yield and activity were 6.2 × 106 protoplasts/g fresh weight [FW] and 87.85%, respectively, by using 0.5 mol/L mannitol, enzyme concentrations of 2.5% cellulase R-10 and 0.8% Macerozyme R-10 at 24 °C for 4 h. At the same time, transfection efficiency of protoplasts was up to 78.49% when using 30 μg plasmid, 40% polyethylene glycol (PEG) concentration, 24 °C incubation temperature, and 20 min transfection time. This is the first efficient protoplasts' isolation and transient transformation system of Phelipanche aegyptiaca haustorium, laying a foundation for future studies on the gene function and mechanisms of haustorium formation in parasitic plants.

Pectin Remodeling and Involvement of AtPME3 in the Parasitic Plant-Plant Interaction, Phelipanche ramosa-Arabidospis thaliana.

Phelipanche ramosa is a root parasitic plant fully dependent on host plants for nutrition and development. Upon germination, the parasitic seedling develops inside the infected roots a specific organ, the haustorium, thanks to the cell wall-degrading enzymes of haustorial intrusive cells, and induces modifications in the host's cell walls. The model plant Arabidopsis thaliana is susceptible to P. ramosa; thus, mutants in cell wall metabolism, particularly those involved in pectin remodeling, like Atpme3-1, are of interest in studying the involvement of cell wall-degrading enzymes in the establishment of plant-plant interactions. Host-parasite co-cultures in mini-rhizotron systems revealed that parasite attachments are twice as numerous and tubercle growth is quicker on Atpme3-1 roots than on WT roots. Compared to WT, the increased susceptibility in AtPME3-1 is associated with reduced PME activity in the roots and a lower degree of pectin methylesterification at the host-parasite interface, as detected immunohistochemically in infected roots. In addition, both WT and Atpme3-1 roots responded to infestation by modulating the expression of PAE- and PME-encoding genes, as well as related global enzyme activities in the roots before and after parasite attachment. However, these modulations differed between WT and Atpme3-1, which may contribute to different pectin remodeling in the roots and contrasting susceptibility to P. ramosa. With this integrative study, we aim to define a model of cell wall response to this specific biotic stress and indicate, for the first time, the role of PME3 in this parasitic plant-plant interaction.

Antioxidant, Antiproliferative and Antibacterial Activity of Phoradendron californicum Extracts; a Parasitic Plant from Northwestern Mexico

Phoradendron californicum is a plant native of northwestern Mexico that has been used as a therapeutic alternative. In the present study, methanolic and chloroformic extracts of P. californicum were prepared and evaluated for their antioxidant activities, phenolic and flavonoid content, as well as their antiproliferative activity in cancer cells and antibacterial activity. The methanolic extract presented higher antioxidant activity (IC50: 47.62 ± 2.90 μg/mL) and higher total phenol content (186.45 ± 4.58 μg/mL) compared to the chloroformic extract (IC50: ˃400 ug/mL and 13.54 ± 1.57 μg/mL, respectively), both extracts presented similar content of total flavonoids (19.92 ± 1.84 and 25.55 ± 0.73 μg/mL, respectively). On the other hand, the chloroformic extract presented higher antiproliferative activity in the cell lines evaluated (HeLa, PC3 and L929) compared to the methanolic extract, meanwhile, in the antibacterial activity the chloroformic extract presented higher activity against Escherichia coli and Listeria monocytogenes, while the methanolic extract was more active against Salmonella enterica. The clear difference in the biological activities of both extracts may be due to differences in the chemical composition of each due to the extraction method used. P. californicum has potential for the search of new compounds with biological activity