Non-parasitic Plants Research Articles

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.

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.

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.

Antibacterial alternatives using the potential of the ant nest plant (Myrmecodia spp.)

New antimicrobial materials have drawn research and development attention due to antimicrobial resistance. Antimicrobial resistance is expected to pose a significant challenge to life in the future. This review comprehensively elucidates the potential of Myrmecodia spp. as an antibacterial agent by systematically selecting and reviewing the majority of relevant studies published in the past 10 years and retrieved from Scopus, PubMed, Web of Science, and related books. Myrmecodia spp. is a non-parasitic plant that grows as an epiphyte. These essential nutrients for the body, including flavonoids, alkaloids, polyphenols, tannins, and saponins, are found within plants. Myrmecodia spp.’s compound functions as an antibacterial agent. This review synthesizes information from multiple sources detailing Myrmecodia spp.’s antibacterial capacity through various testing methods. Keywords: active compound, antibacterial, feed additive, health, Myrmecodia spp.

Genome-wide analysis of horizontal transfer in non-model wild species from a natural ecosystem reveals new insights into genetic exchange in plants.

Horizontal transfer (HT) refers to the exchange of genetic material between divergent species by mechanisms other than reproduction. In recent years, several studies have demonstrated HTs in eukaryotes, particularly in the context of parasitic relationships and in model species. However, very little is known about HT in natural ecosystems, especially those involving non-parasitic wild species, and the nature of the ecological relationships that promote these HTs. In this work, we conducted a pilot study investigating HTs by sequencing the genomes of 17 wild non-model species from a natural ecosystem, the Massane forest, located in southern France. To this end, we developed a new computational pipeline called INTERCHANGE that is able to characterize HTs at the whole genome level without prior annotation and directly in the raw sequencing reads. Using this pipeline, we identified 12 HT events, half of which occurred between lianas and trees. We found that mainly low copy number LTR-retrotransposons from the Copia superfamily were transferred between these wild plant species, especially those of the Ivana and Ale lineages. This study revealed a possible new route for HTs between non-parasitic plants and provides new insights into the genomic characteristics of horizontally transferred DNA in plant genomes.

Gibberellins promote seed conditioning by up-regulating strigolactone receptors in the parasitic plant Striga hermonthica.

Dormant seeds of a root parasitic plant Striga hermonthica sense strigolactones from host plants as environmental cues for germination. This process is mediated by diversified member of strigolactone receptors encoded by HYPOSENSITIVE TO LIGHT/KARRIKIN INSENSITIVE2 genes. It is known that warm and moist treatment of seed conditioning gradually turns dormant Striga seeds competent to respond strigolactones, while the mechanism behind it has been poorly understood. In this report, we show that plant hormone gibberellins increase the strigolactone-competence by up-regulating mRNA expressions of the major strigolactone receptors during the conditioning period. This idea was supported by poor germination phenotype when gibberellin biosynthesis is depleted by paclobutrazol during conditioning. Moreover, live-imaging with fluorogenic strigolactone-mimic, yoshimulactone green W, revealed that paclobutrazol treatment during conditioning caused aberrant dynamics of strigolactone perception after germination. These observations revealed an indirect role of gibberellins to the seed germination in Striga, which is contrastive to their roles as dominant germination stimulating hormone in non-parasitic plants. We propose a model of how the role of gibberellins become indirect during the evolution of parasitism in plants. Our work also highlight the potential role for gibberellins in field application, for instance, elevating the sensitivity of the seeds towards strigolactones in the current suicidal germination approach to alleviate the agricultural threats caused by this parasite in Africa.

A Divergent Clade KAI2 Protein in the Root Parasitic Plant Orobanche minor Is a Highly Sensitive Strigolactone Receptor and Is Involved in the Perception of Sesquiterpene Lactones.

Strigolactones (SLs) were initially discovered as germination inducers for root parasitic plants. In 2015, three groups independently reported the characterization of the SL receptor in the root parasitic plant Striga hermonthica, which causes significant damage to crop production, particularly in sub-Saharan Africa. The characterized receptors belong to HYPOSENSITIVE TO LIGHT/KARRIKIN INSENSITIVE2 (HTL/KAI2), which is a member of the α/β-hydrolase protein superfamily. In non-parasitic plants, HTL/KAI2 perceives the smoke-derived germination inducer karrikin and a yet-unidentified endogenous ligand. However, root parasitic plants evolved a specific clade of HTL/KAI2 that has diverged from the KAI2 clade of non-parasitic plants. The S. hermonthica SL receptors are included in this specific clade, which is called KAI2 divergent (KAI2d). Orobanche minor is an obligate root holoparasitic plant that grows completely dependent on the host for water and nutrients because of a lack of photosynthetic ability. Previous phylogenetic analysis of KAI2 proteins in O. minor has demonstrated the presence of at least five KAI2d clade genes. Here, we report that KAI2d3 and KAI2d4 in O. minor have the ability to act as the SL receptors. They directly interact with SLs in vitro, and when expressed in Arabidopsis, they rescue thermo-inhibited germination in response to the synthetic SL analog GR24. In particular, KAI2d3 showed high sensitivity to GR24 when expressed in Arabidopsis, suggesting that this receptor enables highly sensitive SL recognition in O. minor. Furthermore, we provide evidence that these KAI2d receptors are involved in the perception of sesquiterpene lactones, non-strigolactone-type germination inducers.

A New Series of Strigolactone Analogs Derived From Cinnamic Acids as Germination Inducers for Root Parasitic Plants.

Root parasitic plants such as Striga and Orobanche cause significant damage on crop production, particularly in sub-Saharan Africa. Their seeds germinate by sensing host root-derived signaling molecules called strigolactones (SLs). SL mimics can be used as suicidal germination inducers for root parasitic plants. Previous attempts to develop such chemicals have revealed that the methylbutenolide ring (D-ring), a common substructure in all the naturally occurring SLs, is critical for SL agonistic activity, suggesting that it should be possible to generate new SL mimics simply by coupling a D-ring with another molecule. Because structural information regarding SLs and their receptor interaction is still limited, such an approach might be an effective strategy to develop new potent SL agonists. Here, we report development of a series of new SL analogs derived from cinnamic acid (CA), the basis of a class of phenylpropanoid natural products that occur widely in plants. CA has an aromatic ring and a double-bond side-chain structure, which are advantageous for preparing structurally diverse derivatives. We prepared SL analogs from cis and trans configuration CA, and found that all the cis-CA-derived SL analogs had stronger activities as seed germination inducers for the root parasitic plants, Orobanche minor and Striga hermonthica, compared with the corresponding trans-CA-derived analogs. Moreover, introduction of a substitution at the C-4 position increased the germination-stimulating activity. We also found that the SL analogs derived from cis-CA were able to interact directly with SL receptor proteins more effectively than the analogs derived from trans-CA. The cis isomer of CA was previously reported to have a growth promoting effect on non-parasitic plants such as Arabidopsis. We found that SL analogs derived from cis-CA also showed growth promoting activity toward Arabidopsis, suggesting that these new SL agonists might be useful not only as suicidal germination inducers for root parasitic weeds, but also as plant growth promoters for the host plants.

How do holoparasitic plants exploit vitamin K1?

ABSTRACT Phylloquinone (vitamin K1) is a thylakoid-embedded electron carrier essential for photosynthesis. Paradoxically, we found that phylloquinone biosynthesis is retained in the nonphotosynthetic holoparasite Phelipanche aegyptiaca (Egyptian broomrape). The phylloquinone pathway genes are preferentially expressed during development of the invasive organ, the haustorium, and exhibit strong coexpression with redox-active proteins known to be involved in parasitism. Unlike in photoautotrophic taxa, the late pathway genes of the holoparasite lack the chloroplast-targeting sequence and their proteins are targeted to the plasma membrane instead. Plasma membrane phylloquinone may enable Phelipanche to sense changes in the redox environment during host interactions. The N-truncated isoforms are conserved in several other Orobanchaceae root holoparasites, and interestingly, in a number of closely related photoautotrophic species as well. This suggests an ancient origin of distinct phylloquinone pathways predating the evolution of parasitic plants in the Orobanchaceae. These findings represent exciting opportunities to probe plasma membrane phylloquinone function and diversification in parasitic and nonparasitic plant responses to external redox chemistry in the rhizosphere.

The Effect of Botanicals with Nematicidal Activity on the Structural and Functional Characteristics of the Soil Nematode Community

We investigated the effects of three botanicals with nematicidal properties (anise-Pimpinella anisum, parsley-Petroselinum crispum, and rocket-Eruca sativa) on the soil nematode community, in terms of trophic structure and nematode genera composition. We compared effects with those of fluopyram (synthetic nematicide) and Nemagold (bionematicide). We assessed the role of time, by sampling 15 and 45 days after treatments and analyzing nematode genera and microbial phospholipid fatty acid biomarkers (PLFA). Soil incorporation of botanicals reduced plant parasitic nematodes, increased bacterivores, especially the enrichment opportunists and among them Rhabditis, having no effect on fungivores and non-parasitic plant feeders. Neither the number nor the composition and dominance hierarchy of nematode genera were affected. Nemagold did not induce any significant change, while fluopyram decreased both free-living and parasitic nematodes, but with no uniform effect against all genera. The least affected genus was the fungivorous Aphelenchus. While most microbial PLFAs increased with time, the abundances of nematode genera did not change, except the Meloidogyne incognita second stage juveniles, which emerged in soil only 45 days after treatments. The low enrichment index and high channel index values of the fluopyram soil samples indicated a stressful environment. The opposite was observed in the botanical treatments, especially parsley and rocket.

A Phelipanche ramosa KAI2 protein perceives strigolactones and isothiocyanates enzymatically

Phelipanche ramosa is an obligate root-parasitic weed that threatens major crops in central Europe. In order to germinate, it must perceive various structurally divergent host-exuded signals, including isothiocyanates (ITCs) and strigolactones (SLs). However, the receptors involved are still uncharacterized. Here, we identify five putative SL receptors in P. ramosa and show that PrKAI2d3 is involved in the stimulation of seed germination. We demonstrate the high plasticity of PrKAI2d3, which allows it to interact with different chemicals, including ITCs. The SL perception mechanism of PrKAI2d3 is similar to that of endogenous SLs in non-parasitic plants. We provide evidence that PrKAI2d3 enzymatic activity confers hypersensitivity to SLs. Additionally, we demonstrate that methylbutenolide-OH binds PrKAI2d3 and stimulates P. ramosa germination with bioactivity comparable to that of ITCs. This study demonstrates that P. ramosa has extended its signal perception system during evolution, a fact that should be considered for the development of specific and efficient biocontrol methods.

WARPP-web application for the research of parasitic plants.

The lifestyle of parasitic plants is associated with peculiar morphological, genetic, and physiological adaptations that existing online plant-specific resources fail to adequately represent. Here, we introduce the Web Application for the Research of Parasitic Plants (WARPP) as an online resource dedicated to advancing research and development of parasitic plant biology. WARPP is a framework to facilitate international efforts by providing a central hub of curated evolutionary, ecological, and genetic data. The first version of WARPP provides a community hub for researchers to test this web application, for which curated data revolving around the economically important Broomrape family (Orobanchaceae) is readily accessible. The initial set of WARPP online tools includes a genome browser that centralizes genomic information for sequenced parasitic plant genomes, an orthogroup summary detailing the presence and absence of orthologous genes in parasites compared with nonparasitic plants, and an ancestral trait explorer showing the evolution of life-history preferences along phylogenies. WARPP represents a project under active development and relies on the scientific community to populate the web app's database and further the development of new analysis tools. The first version of WARPP can be securely accessed at https://parasiticplants.app. The source code is licensed under GNU GPLv2 and is available at https://github.com/wickeLab/WARPP.

Effect of Homeopathic Preparations on Lettuce, Parasitized or Not by Meloidogyne enterolobii.

There are relatively few scientific works on the use of homeopathy to manage plant pathogens, particularly nematodes. A handful of studies focused on Meloidogyne spp. parasitizing vegetables have brought contradictory results on nematode control and enhancement of plant tolerance to parasitism. Our goal was to assess the effect of Cina-a well-known anti-nematode ingredient-on Meloidogyne enterolobii parasitizing lettuce. Cina was applied daily on nematode-inoculated plants, from the seedling stage until harvest. We tested an evenly spaced range of Hahnemannian concentrations (c), which were applied though irrigation with a constant dose of the ingredient. Several absolute and relative controls were employed to allow the assessment of the effect of Cina on nematode reproduction and lettuce growth. Cina affected growth of non-parasitized plants, both positively and negatively; this effect was modulated by the c applied and the thermal stress suffered by the plants in one of the assays. The effect of Cina on the growth of nematode-parasitized plants was neutral or negative. Cina reduced nematode reproduction by 25-36%. Based on the moderate negative effect of Cina on M. enterolobii reproduction, it seems this ingredient may be useful as a complementary strategy for Meloidogyne control. But Cina did not enhance the tolerance of lettuce to Meloidogyne spp.

Quinone perception in plants via leucine-rich-repeat receptor-like kinases.

Quinones are produced and sensed in all kingdoms of life1-4. Plants are primary producers of quinone1,2, but the role of quinone as a signalling agent in plants remains largely unknown. One well-documented role of quinone is in the induction of haustoria (specialized feeding structures) in plants that parasitize roots, which occurs in the presence of the host-derived quinone compound 2,6-dimethoxy-1,4-benzoquinone (DMBQ)5. However, how parasitic plants sense DMBQ remains unclear, as is whether nonparasitic plants are capable of sensing quinones. Here we use Arabidopsis thaliana and DMBQ as a model plant and quinone to show that DMBQ signalling occurs in Arabidopsis via elevation of cytosolic Ca2+ concentration. We performed a forward genetic screen in Arabidopsis that isolated DMBQ-unresponsive mutants, which we named cannot respond to DMBQ1 (card1). The CANNOT RESPOND TO DMBQ1 (CARD1; At5g49760, also known as HPCA1) gene encodes a leucine-rich-repeat receptor-like kinase that is highly conserved in land plants. In Arabidopsis, DMBQ triggers defence-related gene expression, and card1 mutants show impaired immunity against bacterial pathogens. In Phtheirospermum japonicum (a plant that parasitizes roots), DMBQ initiates Ca2+ signalling in the root and is important for the development of the haustorium. Furthermore, CARD1 homologues from this parasitic plant complement DMBQ-induced elevation of cytosolic Ca2+ concentration in the card1 mutant. Our results demonstrate that plants-unlike animals and bacteria-use leucine-rich-repeat receptor-like kinases for quinone signalling. This work provides insights into the role of quinone signalling and CARD1 functions in plants that help us to better understand the signalling pathways used during the formation of the haustorium in parasitic plants and in plant immunity in nonparasitic plants.

The mistletoe Struthanthus flexicaulis reduces dominance and increases diversity of plants in campo rupestre

The interaction between hemiparasites and their host plants is an important structuring mechanism for plant communities. The mistletoe Struthanthus flexicaulis (Loranthaceae) is widely distributed in the campo rupestre ecosystem and likely has an important role in structuring the communities of which its hosts are part. The main goals of this study were to investigate the effects of parasitism by S. flexicaulis on host plants in a degraded area of campo rupestre and to determine how parasitism affects characteristics of the structure of this plant community over time. We found that parasitized plants had smaller crowns and branch growth, and suffered higher mortality compared to non-parasitized plants. Parasitism by S. flexicaulis decreased dominance and increased the diversity and evenness of plants in the community over time. Parasitism leads to competition with the host for water and nutrients, which may decrease the performance of the host and, consequently, leading to host death. The high mortality of the most abundant plant species led to a restructured woody plant community. These results reinforce the importance of parasitic plants that frequently play a key role in maintaining species diversity in plant communities.

SMAX1-dependent seed germination bypasses GA signalling in Arabidopsis and Striga.

Parasitic plant infestations dramatically reduce the yield of many major food crops of sub-Saharan Africa and pose a serious threat to food security on that continent1. The first committed step of a successful infestation is the germination of parasite seeds primarily in response to a group of related small-molecule hormones called strigolactones (SLs), which are emitted by host roots2. Despite the important role of SLs, it is not clear how host-derived SLs germinate parasitic plants. In contrast, gibberellins (GA) acts as the dominant hormone for stimulation of germination in non-parasitic plant species by inhibiting a set of DELLA repressors3. Here, we show that expression of SL receptors from the parasitic plant Striga hermonthica in the presence of SLs circumvents the GA requirement for germination of Arabidopsis thaliana seed. Striga receptors co-opt and enhance signalling through the HYPOSENSITIVE TO LIGHT/KARRIKIN INSENSITIVE 2 (AtHTL/KAI2) pathway, which normally plays a rudimentary role in Arabidopsis seed germination4,5. AtHTL/KAI2 negatively controls the SUPPRESSOR OF MAX2 1 (SMAX1) protein5, and loss of SMAX1 function allows germination in the presence of DELLA repressors. Our data suggest that ligand-dependent inactivation of SMAX1 in Striga and Arabidopsis can bypass GA-dependent germination in these species.

Population-Specific Selection on Standing Variation Generated by Lateral Gene Transfers in a Grass.

Evidence of eukaryote-to-eukaryote lateral gene transfer (LGT) has accumulated in recent years [1-14], but the selective pressures governing the evolutionary fate of these genes within recipient species remain largely unexplored [15, 16]. Among non-parasitic plants, successful LGT has been reported between different grass species [5, 8, 11, 16-19]. Here, we use the grass Alloteropsis semialata, a species that possesses multigene LGT fragments that were acquired recently from distantly related grass species [5, 11, 16], to test the hypothesis that the successful LGT conferred an advantage and were thus rapidly swept into the recipient species. Combining whole-genome and population-level RAD sequencing, we show that the multigene LGT fragments were rapidly integrated in the recipient genome, likely due to positive selection for genes encoding proteins that added novel functions. These fragments also contained physically linked hitchhiking protein-coding genes, and subsequent genomic erosion has generated gene presence-absence polymorphisms that persist in multiple geographic locations, becoming part of the standing genetic variation. Importantly, one of the hitchhiking genes underwent a secondary rapid spread in some populations. This shows that eukaryotic LGT can have a delayed impact, contributing to local adaptation and intraspecific ecological diversification. Therefore, while short-term LGT integration is mediated by positive selection on some of the transferred genes, physically linked hitchhikers can remain functional and augment the standing genetic variation with delayed adaptive consequences.

Mistletoe effects on the host tree Tapirira guianensis: insights from primary and secondary metabolites

Mistletoes are parasitic plants that are capable of penetrating the living tissue of another plant’s stems and branches and extracting the necessary resources for their survival. This study aimed to compare the leaves and branches of parasitized and non-parasitized Tapirira guianensis host trees to gain insights of reciprocal effects of Phoradendron perrottetii (mistletoe) infection and profiles of primary metabolites and phenolic compounds of T. guianensis. Our hypothesis was that either the host’s chemical profile determines mistletoe infestation, or that the mistletoe infestation leads to fundamental changes in the metabolite profile of the host. Plant material was collected from T. guianensis parasitized by P. perrottetii, yielding samples from infested and non-infested host branches and their respective leaves. Infested branches were divided into two regions, the proximal region and the host-parasite interface (gall) region. Leaves and branches of non-parasitized plants were also collected. Statistical analyses revealed negative effects of the parasite on infested branches regarding most of the analyzed primary metabolites, especially soluble carbohydrates. This suggests a flow of carbohydrates towards the mistletoe, indicating a partially heterotrophic nutrition. Additionally, we observed a positive effect on the tannin contents of non-infested host branches caused by the mistletoe, which might suggest that this parasitic relationship induces a systemic response in T. guianensis. Finally, high contents of flavonoids at the gall region could indicate a mechanism of ROS quenching.

Синантропна рослинність у кам'янистих садах Києва

Визначено основну проблему догляду за кам'янистими садами – боротьба із бур'янами. Виявлено синатропну рослинність (бур'яни) кам'янистих садів Києва. Наведено перелік бур'янів, які найчастіше трапляються на дослідних ділянках. Дослідження проведено у насадженнях різного функціонального призначення (насадження загального користування, насадження обмеженого користування, насадження спеціального призначення). Проаналізовано 19 видів бур'янів, які належать до 12 родин, враховано способи їх поширення і причини стійкості в кам'янистих садах. Встановлено, що поширення бур'янів дуже виснажують ґрунт, ускладнюють догляд за кам'янистим садом, знижують загальну декоративність кам'янистих композицій, сприяють розвитку шкідників та хвороб. Запропоновано методи боротьби з бур'янами та низку інших агротехнічних заходів, які покращать декоративний вигляд кам'янистих садів. Виділено біологічні групи малорічних та багаторічних бур'янів. Виявлено, що за тривалістю життя в насадженнях переважають однорічні бур'яни, які належить до класу Дводольні. Проаналізовано спектр дії гербіцидів та визначено найефективніші препарати для боротьби з бур'янами. Залежно від виду препарату та інтенсивності росту бур'янів у кам'янистих садах запропоновано кратність оброблення гербіцидами. Дослідження за ростом бур'янів здійснено від ранньої весни до пізньої осені. Роботу виконано шляхом маршрутних обстежень.

Factors affecting the efficiency of Rhizobium rhizogenes root transformation of the root parasitic plant Triphysaria versicolor and its host Arabidopsis thaliana

BackgroundRhizobium rhizogenes transformation is commonly used to generate transgenic roots traditionally called hairy roots, for both investigative and commercial applications. While fertile plants can be regenerated from transgenic roots, the transgenic roots are more typically used directly, either to investigate root biology or to produce valuable secondary metabolites. Hairy roots have been particularly useful for genetic studies of rhizosphere interactions; including the recognition of host plant roots by the roots of parasitic angiosperms.ResultsIn this manuscript we analyzed various environmental, nutritional and procedural conditions for their effects on transformation of the model hemi-parasitic plant Triphysaria versicolor and Arabidopsis thaliana, one of its hosts. We first examined the effects of media, gelling agents and co-incubation times on Triphysaria root transformation and determined that while all three affected transformation rates, the media were the most significant. Once those primary conditions were fixed, we examined the roles of seedling age, explant type, acetosyringone, temperature and illumination on Triphysaria hairy root transformation rates. Using the optimized procedure approximately 70% of Triphysaria seedlings developed transgenic roots as judged by expression of YFP. These conditions were then used to transform Arabidopsis and similar transformation rates were obtained.ConclusionsAnalyses of root transformation factors provides a method recovering transgenic roots from both parasitic plants and their hosts at high frequency. In addition to providing an effective in vitro approach for genetic investigations of parasitic plant-host plant interactions, these results are applicable to genetic studies of non-parasitic plants as well.