Root Parasite Research Articles

Distribution patterns and influencing factors of different parasitic angiosperm types in China

Parasitic plants are widely distributed in major biomes. They can be categorized into root parasites and stem parasites in terms of parasitic sites or divided into hemiparasites and holoparasites according to the degree of nutritional dependence on their hosts via haustoria. However, little is known concerning distribution patterns of different parasitic plant types and their determinants, which may be helpful for effective management and ecological conservation. Here, we collated an updated checklist of parasitic angiosperms in China and examined the distribution pattern of the four types, and then performed multiple linear regression analysis and redundancy analysis of 22 influencing factors representing biotic, topographic, and climatic factors. There are 745 species of parasitic angiosperms in China, belonging to 50 genera and 12 families. Regarding root parasites, most appeared in the west of China than in the east; while stem parasites showed a broader north-south divide in distribution. Hemiparasites were fewer in the east and more in the southwest. However, holoparasites displayed a patchy distribution across China. The results of redundancy analysis (after eliminating multicollinearity effects) showed that explained variation of root parasites, stem parasites, and hemiparasites was 87.9%, 93.7%, and 87.0%, respectively; while that of holoparasites was only 57.8%. Therefore, the four types of parasitic angiosperms varied quite distinctly in terms of distribution patterns across China. Seed plant richness was one of the common leading factors affecting distributions of root parasites, stem parasites, and hemiparasites in China. Besides, the other major influencing factors were the maximum temperature of the warmest month (Bio5), temperature seasonality (Bio4) and precipitation of the warmest quarter (Bio18), and isothermality (Bio3), respectively. Additionally, the main factor affecting holoparasites’ distribution was the temperature (Bio3). We found that different parasitic angiosperm types in China were mainly affected by the biotic factor, temperature, and precipitation. In addition, the whole flora of parasites was similar to root parasites and hemiparasites in distribution; nevertheless, its leading factors were the same as those of hemiparasites. Our findings reveal the various responses of different parasitic angiosperm types to the environmental changes across China. It probably comes down to the evolutionary relationships and life strategies among these different types.

Involvement of strigolactone hormone in root development, influence and interaction with mycorrhizal fungi in plant: Mini-review.

Arbuscular mycorrhizal fungi (AMF) and plant symbiosis is the old, fascinating and beneficial relation that exist on earth for the plants. In this review, we have elaborated that the strigolactones (SLs) are released from the roots and function with root parasite, seeds and symbiotic AMF as contact chemicals. They are transported through the xylem in the plants and can regulate plant architecture, seed germination, nodule formation, increase the primary root length, influence the root hairs and physiological reactions to non-living agents by regulating their metabolism. SLs first evolved in ancient plant lineages as regulators of the basic production processes and then took a new role to maintain the growing biological complexities of terrestrial plant. SLs belongs to a diversified category of butenolide-bearing plant hormones related to various processes of agricultural concern. SLs also arouses the development of spores, the divergence and enlargement of hyphae of AMF, metabolism of mitochondria, reprogramming of transcription process, and generation of chitin oligosaccharides which further stimulate the early response of symbiosis in the host plant, results from better communication in plant and ability of coexistence with these fungi. The required nutrients are transferred from the roots to the shoots, which affect the physiological, biochemical, and morphological characteristics of the plant. On the other hand, the plant provides organic carbon in the form of sugars and lipids to the fungi, which they use as a source of energy and for carried out different anabolic pathways. SLs also lead to alteration in the dynamic and structure of actin in the root region as well as changes the auxin's transporter localization in the plasma membrane. Thus, this study reveals the functions that SLs play in the growth of roots, as well as their effect and interaction with AMF that promote plant growth.

Field Screening of Sorghum [Sorghum bicolor (L.) Moench] Inbred Lines for Resistance to Striga [Striga hermonthica (Del.)] in East Hararghe, Ethiopia

Drought and the obligate Striga root parasite are two of the most important constraints to sorghum production in the northern and north eastern parts of Ethiopia. This study assessed the field reaction of selected advanced lines under Striga hermonthica infestation condition. Twenty-two sorghum genotypes with two resistant checks (Gobiye and SRN-39) and one susceptible check (Teshale) were evaluated under Striga hot spot area at Fadis Agricultural Research Center, Boko research station (Ethiopia) in the 2016 season using a 5x5 triple lattice design. During the field experiment, 11 parameters were measured among which Striga count emerged on each genotype was the indicator of resistance genotypes. Genotypes differed significantly in all measured parameters in their reactions to Striga. Genotypes 2006 MW 6044, ETSC 300003, ETSC 300081, 05 MW 6019, and ETSC 300080 showed Striga resistance in the field. Thus, these genotypes were the most promising sources of resistance to S. hermonthica. From field experiments, it could be suggested that genetic variability for resistance and tolerance is available in a range of genotypes, which could be used for future breeding and production in Striga infested areas. Keywords: genotypes, germination stimulant, parasitic weed, resistant, screening techniques DOI: 10.7176/FSQM/105-01 Publication date: February 28 th 2021

Prohexadione calcium is herbicidal to the sunflower root parasite Orobanche cumana.

The obligatory sunflower root parasite Orobanche cumana Wallr. deprives its host of essential nutrients, resulting in a dramatic reduction in yield and biomass. A post-emergence application with an imidazolinone herbicide on an imidazolinone-tolerant sunflower is highly effective against O. cumana. The herbicide inhibits the enzyme acetohydroxy acid synthase and consequently, growth of the parasite is inhibited, although the sunflower survives the treatment through mutations in the target enzyme. Interestingly, field studies have shown that a combined application of an imidazolinone herbicide with prohexadione resulted in reduced emergence of O. cumana compared with the sole application of the herbicide. The aim of this study was to investigate whether prohexadione is herbicidal to O. cumana. Prohexadione was rapidly distributed within the sunflower, reaching the roots, the site of O. cumana attack, as early as 6 h after application (HAA) on sunflower leaves. A direct impact of prohexadione on O. cumana germination was investigated and a half-maximal inhibitory concentration (IC50 ) of 84 μm prohexadione was found. In addition, the inhibition of germination by prohexadione was terminal, meaning that O. cumana seeds died after prohexadione contact as soon as they were primed for germination. Additionally, excretion studies showed that a small proportion of the applied prohexadione was excreted by sunflower roots. We show that prohexadione is an inhibitor of O. cumana germination and that the growth regulator is found in sunflower roots shortly after application. We hypothesize that prohexadione is excreted in sufficient amounts from the sunflower roots, therefore having a direct impact on O. cumana germination. © 2020 Society of Chemical Industry.

On the macro-micro-morphology of organs of host invasion in hemiparasite Helicanthes elasticus (Desv.) Danser.

Loranthaceae family includes hemiparasitic members which are seen invading a wide range of commercial crops. Helicanthes elasticus (Desv.) Danser is very common on mango trees. Though parasitic in nature, this mistletoe is also medicinally important as fetoprotective, against vesicular calculi and kidney infections. This study is an attempt to document macro-microscopical features of parasitic root, fruit and host-mistletoe tissue interaction in the haustorium of H. elasticus growing on mango stems. Collection, preservation, sectioning, staining and photomicrography of the root, fruit and host-mistletoe union were done as per standard methodologies of anatomical studies. Though there is resemblance to the normal roots in morphology as well as anatomy, the microscopic finding of large number of branched stone cells in the roots is interesting. The morpho-anatomical features recorded would help in understanding the infection biology of this mistletoe. The eradication during the earlier stages of its establishment from seed or from the root creeping over the surface of the host can help in controlling this parasite infection on commercially important host plants.

The Effect of Virulence and Resistance Mechanisms on the Interactions between Parasitic Plants and Their Hosts.

Parasitic plants have a unique heterotrophic lifestyle based on the extraction of water and nutrients from host plants. Some parasitic plant species, particularly those of the family Orobanchaceae, attack crops and cause substantial yield losses. The breeding of resistant crop varieties is an inexpensive way to control parasitic weeds, but often does not provide a long-lasting solution because the parasites rapidly evolve to overcome resistance. Understanding mechanisms underlying naturally occurring parasitic plant resistance is of great interest and could help to develop methods to control parasitic plants. In this review, we describe the virulence mechanisms of parasitic plants and resistance mechanisms in their hosts, focusing on obligate root parasites of the genera Orobanche and Striga. We noticed that the resistance (R) genes in the host genome often encode proteins with nucleotide-binding and leucine-rich repeat domains (NLR proteins), hence we proposed a mechanism by which host plants use NLR proteins to activate downstream resistance gene expression. We speculated how parasitic plants and their hosts co-evolved and discussed what drives the evolution of virulence effectors in parasitic plants by considering concepts from similar studies of plant–microbe interaction. Most previous studies have focused on the host rather than the parasite, so we also provided an updated summary of genomic resources for parasitic plants and parasitic genes for further research to test our hypotheses. Finally, we discussed new approaches such as CRISPR/Cas9-mediated genome editing and RNAi silencing that can provide deeper insight into the intriguing life cycle of parasitic plants and could potentially contribute to the development of novel strategies for controlling parasitic weeds, thereby enhancing crop productivity and food security globally.

Antidiabetic and hepatoprotective potential of whole plant extract and isolated compounds of Aeginetia indica

BackgroundAeginetia indica, a perennial herb from the Orobanchaceae family, generally grows as a root parasite and is widely distributed in the forests of South and South-Asian countries. The plant has valuable uses in herbal medicine against various diseases, such as diabetes, liver diseases, and arthritis. Aim of the studyThe present study was designed to investigate the antidiabetic and hepatoprotective effects of the methanol extract of the whole plant of A. indica in a mouse model followed by the isolation of bioactive compounds and their in-silico studies. MethodsThe hepatoprotective effects were evaluated in a paracetamol-induced hepatotoxicity mouse model. The antidiabetic effects were examined by an oral glucose tolerance test and in an alloxan-induced diabetes mouse model. ResultsThe plant extract, at a dose of 400 mg/kg, caused a significant reduction (p < 0.001) in liver enzyme concentrations, including alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase, similar to the effects of standard drug silymarin. The plant extract, at 400 mg/kg, also significantly reduced (p < 0.001) the fasting blood glucose concentration by 27.33 % after 3 h, compared with a reduction of 45.31 % in response to glibenclamide. In the alloxan-induced diabetes model mice, significant reductions (p < 0.05) in elevated glucose concentrations were observed on days 10 and 20 in mice treated with plant extract and glibenclamide. Chromatographic analyses and nuclear magnetic resonance (NMR) studies identified the presence of β-sitosterol, stigmasterol, and oleic acid in the extract. The possible mechanism underlying the antidiabetic effects was revealed by molecular docking analyses examining the binding of β-sitosterol and stigmasterol with sirtuin 4, an NAD-dependent deacylase enzyme that downregulates leucine-induced and glutamate dehydrogenase-induced insulin secretion. The binding affinities between sirtuin 4 and β-sitosterol, stigmasterol, and NAD were found to be −8.6 kcal/mol, −7.2 kcal/mol and −9.5 kcal/mol, respectively, indicating the probable competition between NAD and the isolated components for sirtuin 4. ConclusionThe present study revealed that A. indica exerted protective effects against alloxan-induced diabetes and paracetamol-induced hepatotoxicity in mice, which supports the findings regarding the use of A. indica during traditional medical practice.

Comparative analysis of two Orobanche cumana Wallr. accessions with a different virulence

Orobanche cumana Wallr. is a root parasite significantly affecting sunflower production in most cultivating countries. Due to the continuous introduction of resistant sunflower hybrids, the parasite evolves rapidly, developing new, more virulent races. In this context, extensive knowledge of the distinctive peculiarities of races and their pathogenicity is needed to understand the broomrape evolution and develop effective control strategies. The present study examines the comparative morphologic, genetic, transcriptomic, and proteomic analysis of two O. cumana accessions with different level of virulence (belonging to race E and H, respectively). Using simple sequence repeats (SSR) and inter-simple sequence repeats (ISSR) markers, specific amplicons suitable for distinguishing between races have been revealed. It has also been found that the genes PME, PGU, PRX, and CHS that encode enzymes associated with host invasion, such as pectin methylesterases, polygalacturonases, peroxidases, and chalcone synthases, respectively, were upregulated in race H compared to E at different developmental stages, confirming their role in the pathogenicity of broomrape. The proteomic analysis has showed 19 differentially expressed proteins (DEP), including 6 specific for race E and 13 specific for race H. A number of DEP were identified as enzymes of the respiratory system, cell wall-modifying enzymes, stress-related proteins, and other proteins known to be involved in the invasion of the host, and might be important for the more virulent race H. Obtained results provide new insight into broomrape parasitism and offer new opportunities for controlling this pathogen.

On improving strigolactone mimics for induction of suicidal germination of the root parasitic plant Striga hermonthica.

Strigolactones (SLs) are plant hormones that regulate the branching of plants and seed germination stimulants of root parasitic plants. As root parasites are a great threat to agricultural production, the use of SL agonists could be anticipated to provide an efficient method for regulating root parasites as suicidal germination inducers. A series of phenoxyfuranone-type SL mimics, termed debranones, has been reported to show potent bioactivities, including reduction of the tiller number on rice, and stimulation of seed germination in the root parasite Striga hermonthica. To exert both activities, two substituents on the phenyl ring of the molecules were important but at least a substituent at the 2-position must be an electron-withdrawing group. However, little is known about the effect of the properties of the substituents at the 2-position on bioactivities. Here, we found that different substituents at the 2-position give different preferences for bioactivities. Halogenated debranones were more effective than the others and SL agonist GR24 for inhibiting rice tiller but far less effective in the induction of S. hermonthica germination. Meanwhile, nitrile and methyl derivatives clearly stimulated the germination of S. hermonthica seeds. Although their IC50 values were 100 times higher than that of GR24 in the receptor competitive binding assay, their physiological activities were approximately 1/10 of GR24. These differences could be due to their uptake in plants and/or their physicochemical stability under our experimental conditions. These findings could support the design of more potent and selective SL agonists that could contribute to solving big agricultural issues.

Root fungal communities associated with better performance of an invasive spring ephemeral

While invasive plants can form dense infestations capable of suppressing native plants in some habitats, in others, they may be much less dominant. Lesser celandine (Ranunculus ficaria) is an invasive spring ephemeral in the northeastern United States and the Pacific Northwest. One possibility for the differences in performance of R. ficaria in invaded areas is the presence of fungal–root associations. We hypothesized that plant performance (biomass and reproductive output) would be driven by community composition of root-associated fungi. Eight invaded sites with a history of variable plant performance were chosen in Cleveland, Ohio. At each site, eight samples (n = 64) were collected along a transect. Terminal restriction fragment length polymorphism and cloning were used in conjunction to determine differences in the root-associated mycobiota colonizing R. ficaria. Microscopy was used to confirm the presence of structures indicative of root-associated fungi. R. ficaria roots were potential hosts to a diverse group of fungi. R. ficaria colonized by root-associated fungal communities consisting of dark septate endophytes and fungi typically associated with ericoid mycorrhizae had a significantly higher average biomass and bulbil counts than plants colonized by parasitic root mycobiota. However, fungal colonization was not shown to be associated with differences in the number of R. ficaria tubers present. This indicates that fungal community composition and colonization may influence the biomass and bulbil production of R. ficaria, which can be linked to the success of this invasive.

Kin Recognition in the Parasitic Plant Triphysaria versicolor Is Mediated Through Root Exudates.

Triphysaria is a facultative parasitic plant in the Orobanchaceae that parasitizes the roots of a wide range of host plants including Arabidopsis, Medicago, rice and maize. The important exception to this broad host range is that Triphysaria rarely parasitize other Triphysaria. We explored self and kin recognition in Triphysaria versicolor and showed that exudates collected from roots of host species, Arabidopsis thaliana and Medicago truncatula, induced haustorium development when applied to the roots of Triphysaria seedlings in vitro while those collected from Triphysaria did not. In mixed exudate experiments, Triphysaria exudates did not inhibit the haustorium-inducing activity of those from host roots. Interestingly, when roots of Triphysaria seedlings were treated with either horseradish peroxidase or fungal laccase, the extracts showed haustorium-inducing factor (HIF) activity, suggesting that Triphysaria roots contain the proper substrates for producing HIFs. Transgenic Triphysaria roots overexpressing a fungal laccase gene TvLCC1 showed an increased responsiveness to a known HIF, 2,6-dimethoxy benzoquinone (DMBQ), in developing haustoria. Our results indicate kin recognition in Triphysaria is associated with the lack of active HIFs in root exudates. Treatment of Triphysaria roots with enzymatic oxidases activates or releases molecules that are HIFs. This study shows that exogenously applied oxidases can activate HIFs in Triphysaria roots that had no previous HIF activity. Further studies are necessary to determine if differential oxidase activities in host and parasite roots account for the kin recognition in haustorium development.

A specialized avian seed dispersal system in a dry-fruited nonphotosynthetic plant, Balanophora yakushimensis.

The family Balanophoraceae are among the most unusual of plants because they have aberrant vegetative bodies, highly reduced flowers, and small and reduced embryos (Hansen 1972, Gonzalez et al. 2019). Because the plants lack chlorophyll and are incapable of photosynthesis, they draw nutrition from other organisms. Indeed, like the well-known parasitic plant, Rafflesia, members of the Balanophoraceae acquire both water and nutrients from host plants. They are, therefore, highly specialized root parasites.

Effects of Heterodera avenae on the absorption and translocation of N, P, K, and Zn from the soil in wheat

Cereal cyst nematode (CCN) (Heterodera avenae) is a major root parasite of wheat throughout the world. A pot experiment was conducted in screen house in CCS Haryana Agricultural University, Hisar during 2016–2017 for studying the nutrient uptake by wheat plants infected with H. avenae. Urea, single super phosphate (SSP), Muriate of potash (MOP), and zinc sulfate (Zn SO4) were applied singly and in combinations, and compared with a control without fertilizers. H. avenae reduced the uptake of nutrients (nitrogen (N), phosphorous (P), potassium (K), and Zn) as compared to uninfested soil. Improved nutrients uptake was found in the treatment where all nutrients were applied in soil. Lesser uptake was recorded in the treatment where no nutrient was applied in soil. In the soil, more nutrients were recorded in infested soil as compared to uninfested soil and, nutrients were also more in soil in the treatments where individual nutrients were applied than their combined application.

Transcriptional profiling of underground interaction of two contrasting sunflower cultivars with the root parasitic weed Orobanche cumana

Orobanche cumana is an obligate root parasite which specifically infects roots of Helianthus annuus L., causing severe yield and economic losses in agricultural fields worldwide. For an efficient control strategy, it is necessary to understand specialized host defense mechanisms and the pathogenesis of O. cumana during underground interaction with the host. RNA-Seq was used to simultaneously assess the transcriptome of each of two contrasting sunflower cultivars with O. cumana during their post-attachment interactions. Secretome prediction was applied to identify O. cumana proteins from its transcriptome. Infection of O. cumana triggered insufficient defense responses in the susceptible cultivar as compared to the resistant one, probably due to the failure to fully recognize parasite effectors. Secretome prediction from the O. cumana transcriptome enabled robust identification of 180 proteins associated with O. cumana penetration and infection. Functional annotation of these proteins revealed that they were associated with cell wall degradation, nutrient acquisition and pathogenesis. Additionally, a candidate effector containing a PAR1 domain from O. cumana was preliminarily identified as a potential suppressor of plant defense responses. Secretome prediction shed lights on the molecular mechanisms that O. cumana deployed to manipulate host defense. Successful infection of O. cumana inhibited host defense responses and turned host roots from a sink to a source for efficient nutrient flux towards the parasite. In summary, these findings provide insight into the mechanism underlying O. cumana infection and are important in understanding parasitic-host plant interaction.

Parasitic interactions of Orobanche with selected Nicotiana species and identification of effective resistant genotypes

Tobacco is an important commercial crop in India and other parts of the world. Recently, Orobanche cernua Loefl. (broomrape), a total root parasite is causing considerable yield losses to tobacco crop cultivated in India. Control strategies focusing largely on agronomic practices are not successful in achieving its control. Unfortunately there is no tobacco variety having good levels of resistance to O. cernua is available for managing its menace. Due to lack of the availability of O. cernua resistance even in germplasm of cultivated tobacco species, a study was conducted with seven selected species of Nicotiana viz., N. repanda Lehm., N. benthamiana-repanda, N. nesophila, N. umbratica-nesophila, N. stocktonii, N. paniculata L. and N. tabacum L. cv Siri for identifying Orobanche resistance for further utilization in transferring resistance factors to cultivated tobacco. Emergence of higher number of Orobanche and reduction in plant height and weight in N. paniculata, N. repanda, and N. tobacum cv. Siri indicated they are susceptible. Higher reduction in plant height and weight with less number of Orobache shoots N. stocktonii proved to be a susceptible species. With relatively low reduction in plant height and weight under O. cernua treatment, N. benthamiana-repanda and N. nesophila can be considered as tolerant species. N. umbratica-nesophila with less number of Orobanche spikes, higher plant height and dry weights under both control and treated conditions can be considered as a resistant species and can be used in breeding resistant cultivars. Resistant/tolerant species either increased or maintained their nutrient uptake abilities under parasite infestation thereby maintained their growth.

Root parasitism by Scybalium fungiforme Schott &amp; Endl. is not random among host species in seasonal tropical forest

ABSTRACT Though they comprise 1 % of plant species on the planet, plant parasites are poorly known. They have been considered a threat to cultivated plants and to the conservation of host species in natural areas. Due to the complex interactions they have with their hosts, understanding their biology is fundamental to the development of conservation strategies for both parasite species and their hosts. We sampled two populations of the root parasite Scybalium fungiforme (Balanophoraceae) in seasonal tropical forest fragments to identify its host species and their functional attributes. Among the hosts, Croton floribundus seems to be preferred (68 % of parasitized plants), while four liana species were complementary hosts (32 %). Host species preference differed sharply among fragments and seems to be related to the successional stage of these forests. The hosts C. floribundus and the four liana species are perennial, fast growing and have large vessels, all of which are attributes that enable high water and nutrient acquisition efficiency. Despite a lack of clear host specificity at the species level, functional convergence among parasitized species suggests that host specificity is mediated by functional traits.

Assessing the Performance of Maize (Zea mays L.) as Trap Crops for the Management of Sunflower Broomrape (Orobanche cumana Wallr.)

Sunflower broomrape (Orobanche cumana Wallr.) is a weedy root parasite that causes huge damage to sunflower (Helianthus annuus L.). Trap crop can stimulate parasitic seed germination without attachment in trap crop, and it was considered as economic methods for controlling the parasite. In this study, co-culture and pot experiments were conducted to assess the allelopathic activity of maize (Zea mays L.) to stimulate broomrape seeds germination and to evaluate the performance of maize rotation for reducing sunflower broomrape infection. All the tested maize cultivars could induce sunflower broomrape germination, and the most active maize cultivar was N314, which induced approximately 40% broomrape seeds germination. Rotation of maize significantly reduced broomrape infection on subsequent sunflower and increased sunflower biomass. After cultivated N314 for 3 years, broomrape attachment on sunflower was the lowest (0.8 attachment plant−1), and the dry mass of sunflower shoot (28.7 g plant−1) was approximately twice higher than the sunflower without previous crop. The effectiveness of broomrape management was significantly different among various maize cultivars. Meanwhile, the differences among cultivars were decreased with the years of maize cultivated prolonged. Our results confirmed that maize was significantly effective in reducing the sunflower damage caused by sunflower broomrape and suggested that maize rotation could be included in the integrated management of sunflower broomrape.

Applications of plant growth promoting bacteria and Trichoderma spp. for controlling Orobanche crenata in faba bean

BackgroundOrobanche crenata is an obligate root parasite belonging to Orbanchaceae. Broomrape causes great damage to the faba bean. Several attempts were applied for controlling parasitic weeds. So, the aim of this work is to study the application of Trichoderma spp. as well as three rhizobacteria species in comparison to herbicidal effect of Glyphosate (Glialka 48% WSC) for controlling broomrape infesting faba bean (Vicia faba).Materials and methodsThree pot experiments were carried out in the greenhouse of the National Research Centre, Dokki, Giza, Egypt during two successive winter seasons. Trichoderma inocula were adjusted to 3.6 × 108 propagules/ml and the bacterium inocula were adjusted at 107–109 colony-forming unit (CFU)/ml. All treatments were applied, before 1 week of sowing, at rate of 50 ml per pot in experiments I and II, while 100 ml per pot in experiment III.ResultsTrichoderma spp. (T. harzianum, T. viride and T. vierns) as well as three rhizobacteria species (Pseudomonas fluorescens, Bacillus subtilis and Bacillus pumilus) enhanced the growth parameters in faba bean plants, i.e. shoot length, shoot fresh weight, shoot dry weight and leaf number in the first experiment when applied without O. crenata infection. In the second experiment, all bio-control could protect plants against O. crenata infection, where it had better juvenile number reduction, than glyphosate after 2 months of application. Both B. subtilis and B. pumilus had the highest reduction to juvenile fresh weight, while their effect was equal to herbicide for juvenile dry weight, respectively. The bio-control agents had high effects until the 4th month, but it was less than that of the herbicide. In experiment III, the bio-control agents could highly reduce the juvenile parameters after 2 months, as well as juvenile fresh weight and juvenile dry weight after 4 months, than the herbicide, respectively. The bio-control agents were effective until 6 months, but less than the herbicide effect. All bio-control treatments highly increased the plant growth parameters, than the herbicide.ConclusionThe application of Trichoderma spp. as well as rhizobacteria species could play an important role in controlling broomrape in faba bean as a natural bioherbicide.

Tripartite interaction between Striga spp., cereals, and plant root-associated microorganisms: a review

Abstract Striga spp. is a major threat to cereal and legume production, putting the food security and economy of smallholder farmers in sub-Saharan Africa at severe risk. This is manifested in the fact that Striga spp. infestation can result in up to 90% loss of both cereal and legume production. A consensus exists that there is yet no single measure to efficiently control Striga spp. This is mainly because of the limited fundamental knowledge of the genetics and ecology of Striga spp. and its interaction with its hosts and host root-associated microorganisms, including plant growth-promoting rhizobacteria (PGPR). Since Striga spp. is a root parasite, it is speculated that PGPR play a key role in controlling the emergence and development of Striga spp. At the same time, PGPR may exhibit beneficial effects on growth promotion of the host to strengthen its tolerance against Striga spp. attacks, while on the other hand, it may also induce, similar to biocontrol agents, direct suicidal effects on Striga spp. Such hypothesized associations between Striga spp., crops (e.g., cereals such as sorghum and maize), and PGPR remain largely unknown, and the central question remains if PGPR play an important role in the Striga -crop pathosystem. This knowledge gap is the central impetus of this review. It will elaborate the complex and fascinating tripartite ecological system of cereals, Striga spp. and root-associated microorgamisms. In a first step, the review will provide a comprehensive summary of the pairwise interactions between Striga spp. and cereals, cereals and PGPR, as well as Striga spp. and PGPR. This summary will then merge into the discussion about the yet limited knowledge of the tripartite interaction between cereals, Striga spp., and PGPR. This specifically includes the exploration of recent discoveries related to population genetics and the life cycle of Striga spp, host (cereal) defense responses to and mechanisms of Striga spp. infestation, as well as the inhibitory and stimulatory role of PGPR on Striga spp. seed germination. In a concluding section, remaining research gaps are identified and necessary research perspectives are provided to direct prospective research toward further understanding the relationship between the three biological components paving the avenue to develop biological and environmentally friendly measures to fight off the everlasting threat of Striga spp.

DISTRIBUTION OF PCN PATHOTYPES IN POLAND

Both Globodera rostochiensis (Wollenweber, 1923) Behrens, 1975 and Globodera pallida (Stone, 1973) are considered the most economically important nematode pest. Annual regional survey conduct in Poland have revealed high infestation of pathotype Ro1 to the northwest of the country and presence of new pathotype Ro5 of G. rostochiensis. In 2009-2013 fifty eight soil samples were tested. parasitic root organisms cause significant losses in quantity and quality of potato crops. In many European countries PCN have become a major problem in potato production mainly in starch potato cultivars. The pathotype Ro1 was detected mostly in central and northern Poland and pathotype Ro5 in four separated provinces: malopolskie, lubuskie, lubelskie and pomorskie. The abundance of cysts in location where the new pathotype was detected suggests that is a thread of further spread of pathotype Ro5 of G. rostochiensis in the country. Consequently, producers and farmers need to grow resistant potato cultivars to keep nematode population below damaging level. These results indicate the urgent need to prevent the spread of PCN to non-infested areas. This report focused on identification of nematode pathotypes in soil samples from infested polish fields and presentation of G. rostochiensis distribution on territory of Poland.