Egyptian Broomrape Research Articles

Egyptian broomrape (Phelipanche aegyptiaca): From foe to friend? Evidence of high nutritional value and potential suitability for food use

This study investigates the potential of Egyptian broomrape (E.B.; Phelipanche aegyptiaca, Pers.), a parasitic plant, as a novel food source. This study aimed at (i) determining E.B.’s nutritional parameters, (ii) studying the effect of 10 different hosts on these values, and (iii) assessing its safety through a toxicological evaluation in mice. The results showed that the host plant affects the parasite's nutritional composition. When developed on several hosts, E.B. has similar levels of proteins and total lipids as compared to quinoa seeds, as well as similar essential amino acids profile. However, the parasite shows substantially higher levels of dietary fibers than in quinoa (19.2–30.6 % DW, vs 7.1 % DW), total phenolic compounds (32.92–66.86 mg GAE/gr DW, vs 0.53 mg GAE/gr DW), ascorbic acid (3.1–6.0 mg/gr DW, vs 2.7 mg/gr DW), total ash (7.2–11.5 % DW, vs 2.6 % DW) and several minerals, but lower levels of reducing sugars (263–441 mg/gr DW, vs 479 mg/gr DW), indicating a potential for low glycemic index ingredients. The safety assessment in mice showed no significant toxic effects. These findings suggest that E.B. could be a valuable food source, warranting further investigation into its nutritional benefits and safety for human and animal consumption.

Fusarium fujikuroi as a potential biocontrol agent of the parasitic weed Phelipanche aegyptiaca in tomato

AbstractPhelipanche aegyptiaca (Pers.) Pomel, commonly known as Egyptian broomrape, is an obligate root parasite, infesting solanaceous crops mainly in Mediterranean countries. Certain antagonistic fungi could be effectively used as a biocontrol agent for this parasitic plant. In this study, three fungal isolates (F1, F2 and F3) were obtained from P. aegyptiaca seeds covered with mycelium. The isolates were characterized based on morphological features and ITS and TEF sequence analysis. They were classified as belonging to Fusarium fujikuroi with a sequence similarity of 99.80% and 100%, respectively. The pathogenicity of the isolates on P. aegyptiaca and tomato were determined. In a P. aegyptiaca seed assay, all isolates allowed seed germination with delayed radicle development. Disease severity among the isolates ranged from 40%–70% on the basis of radicle necrotic area. The F1 isolate caused more than 40% disease on the spiders and tubercles in a polyethylene bag assay. The average of the total of spider and tubercle mortality caused by the F1 isolate was 63.5% at 9 days after inoculation. Moreover, the F1 isolate was considered non‐pathogen on tomato with 6.66% disease severity after root inoculation. To the best of our knowledge, this is the first report of F. fujikuroi on P. aegyptiaca seed. Pending further development, the F1 isolate could have potential for the biocontrol of P. aegyptiaca in the future.

Seed germination responses of broomrape species (Phelipanche ramosa and Phelipanche aegyptiaca) to various sanitation chemicals

AbstractBranched broomrape, an obligate root parasitic weed, has recently re-emerged in tomato fields in several California counties. California produces more tomato than any other state, and the outbreak of this noxious weed could potentially wreak havoc on the industry’s economy. Preventive measures must be taken to stop or reduce the spread of branched broomrape seeds to other areas. Branched broomrape can produce thousands of tiny seeds, which can easily spread with farm machinery over short and long distances. To prevent branched broomrape seed dispersal, sanitation and disinfection of farm equipment are necessary before entering a new farm. We tested the effectiveness of various ammonium compounds, including didecyl dimethyl ammonium chloride (DDAC), alkyl dimethyl benzyl ammonium chloride (ADBC), didecyl dimethyl ammonium bromide (DDAB), ammonium bromide (AB), and ammonium chloride (AC) on prevention of branched broomrape seed germination. Dose-response analysis showed that three chemical products, ADBC, DDAB, and DDAC, could completely inhibit branched broomrape seeds (potentially making them nonviable) at 1%, 1%, and 10% wt/vol concentrations, respectively. These three compounds were further tested in an exposure duration experiment that additionally included Egyptian broomrape. Only 10 min of exposure to these compounds was needed to prevent germination of both branched and Egyptian broomrape seeds at 1% (ADBC, DDAB) and 10% wt/vol (DDAC). Lower concentrations can provide similar inhibition effects when combined with longer exposure times. Egyptian broomrape seeds were more sensitive than branched broomrape seeds. Findings suggest that quaternary ammonium compounds could be used as potential sanitation agents to disinfect agriculture machinery from branched and Egyptian broomrape seeds.

Herbicidal secondary metabolites from Bacillus velezensis JTB8-2 against Orobanche aegyptiaca

Egyptian broomrape (Orobanche aegyptiaca) is a parasitic plants that cause significant losses to important crops. The effective methods for controlling this weed are rare. Biological control could be one of the possible strategies to tackle these weeds efficiently. In this work, a bacteria strain Bacillus velezensis JTB8–2 was proven to possesse biological control functions against broomrapes in both pot and field experiments. Four secondary metabolites (1–4) were isolated from the B. velezensis JTB8–2 crude extracts, and all of them could inhibit the germination of O. aegyptiaca seeds at concentrations from 0.5 mM to 4 mM. Their structures were further elucidated by Nuclear Magnetic Resonance (NMR) and Mass Spectrometry (MS) analysis. Among the isolated compounds, 1 and 2 exhibited the strongest herbicidal activity with 100% inhibition rate against the germination of O. aegyptiaca seeds at 4 mM, and thus had great potential in the development of new herbicidal products to control O. aegyptiaca in the future.

Evaluating Branched Broomrape (Phelipanche ramosa) Management Strategies in California Processing Tomato (Solanum lycopersicum).

Detections of the regulated noxious parasitic weed branched broomrape (Phelipanche ramosa) in California tomato fields have led to interest in eradication, sanitation, and management practices. Researchers in Israel developed a decision-support system and herbicide treatment regime for management of Egyptian broomrape (P. aegyptiaca) in tomato. Research was conducted in 2019 and 2020 to evaluate whether similar treatments could be used to manage branched broomrape in California processing tomatoes and to provide registration support data for the herbicide use pattern. Treatment programs based on preplant incorporated (PPI) sulfosulfuron and chemigated imazapic were evaluated in 2019 and 2020 to determine safety on the processing tomato crop and on common rotational crops. Three single-season tomato safety experiments were conducted and a single rotational crop study was conducted in which a tomato crop received herbicide treatments in 2019 and several common rotational crops were planted and evaluated in 2020 in a site without branched broomrape. In 2020, an efficacy study was conducted in a commercial tomato field known to be infested with branched broomrape to evaluate the efficacy of PPI sulfosulfuron and chemigated imazapic, imazapyr, imazethapyr, and imazamox. After two field seasons, sulfosulfuron and imazapic appeared to have reasonable crop safety on tomato in California; however, rotational crop restrictions will need to be considered if sulfosulfuron is used to manage branched broomrape. In the efficacy study, there was a trend in which the sulfosulfuron and imidazolinone treatments had fewer broomrape shoots per plot than the grower standard treatments, however, none were fully effective and there were no significant differences among the various sulfosulfuron and imidazolinone treatment combinations. Additional research is needed to optimize the treatment timing for management of branched broomrape in this cropping system. Because of registration barriers with imazapic in the California market, future research will focus on treatment combinations of PPI sulfosulfuron and chemigated imazamox rather than imazapic.

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.

Effect of Infestation Density with Phelipanche aegyptiaca on the Efficiency of Bio-agent, Phytomyza orobanchia and Infestation by Tuta absoluta on Tomato Crop at El-Beheira Governorate, Egypt

Tomato is the most susceptible hosts to many insect pests and broomrape, which causes significant yield losses. The present study was carried out with the purpose to know which infestation density of Egyptian broomrape (Phelipanche aegyptiaca Pomel) was affected on efficiency the bio-agent, Phytomyza orobanchia Kaltenbach (Diptera: Agromyzidae) in the area grown with tomato crop, which was affected at the same time by tomato leaf miner, Tuta absoluta (Meyrick) (Gelechiidae: Lepidoptera) under natural conditions during two successive years (2019 and 2020) at El-Beheira governorate, Egypt. Three randomized fields cultivated with tomato crop in summer were selected during 2019 and 2020. Infestation densitywith Ph. aegyptiaca was divided into three levels, Low (1 – 10 shoots / plant), Medium (11 – 25 shoots / plant) and High (≥ 25 shoots / plant). Number of pupae in capsules, number of pupae in stems, total number of pupae in shoots and the percentage of pupae in capsules were determined per Ph. aegyptiaca shoot. Highest effectiveness of P. orobanchia (36.0%) was recorded in low infestation density with Ph. aegyptiaca, while with medium and high infestation density with Ph. aegyptiaca only 23.5% and 18.6%, respectively in second year 2020. No significant difference was found between low and medium infestation density with Ph. aegyptiaca in the total number of P. orobanchia pupae per shoot. At the beginning of fruiting stage of tomato crop, leaves and fruits were taken from the randomly selected tomato plants according to infestation density with Ph. aegyptiaca flourishes, to estimate the infestation percent by leaf miner (Tuta absoluta) throughout the two year (2019-2020). In addition to, percentage of parasitism by egg parasitoids of the genus Trichogramma on tomato leaf miner was determined. According to infestation density with Ph. aegyptiaca, tomato yield was calculated. At the end of this study, under the medium infestation density of Egyptian broomrape the infestation percent by T. absoluta was (16.67%) synchronized with high percentage of its parasitoid, Trichogramma spp. (63.2%) with high yield of tomato (820 gm/ plant) compared with control (without infestation with Ph. aegyptiaca). Obtained data may provide information for improving effective of P. orobanchia in biological control program of Ph. aegyptiaca in the frame of integrated pest management (IPM) of T. absoluta in tomato fields. However, combining Egyptian broomrape (Ph. aegyptiaca) and T. absoluta in IPM program will contribute to management efficacy as well as avoid used each control methods separately for each pest. Further research is needed to choose the timing in combining between these pests to use IPM, taking into consideration efficacy, cost and environmental aspects.

Enhanced Production of Aromatic Amino Acids in Tobacco Plants Leads to Increased Phenylpropanoid Metabolites and Tolerance to Stresses.

Aromatic amino acids (AAAs) synthesized in plants via the shikimate pathway can serve as precursors for a wide range of secondary metabolites that are important for plant defense. The goals of the current study were to test the effect of increased AAAs on primary and secondary metabolic profiles and to reveal whether these plants are more tolerant to abiotic stresses (oxidative, drought and salt) and to Phelipanche egyptiaca (Egyptian broomrape), an obligate parasitic plant. To this end, tobacco (Nicotiana tabacum) plants were transformed with a bacterial gene (AroG) encode to feedback-insensitive 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase, the first enzyme of the shikimate pathway. Two sets of transgenic plants were obtained: the first had low expression of the AroG protein, a normal phenotype and minor metabolic changes; the second had high accumulation of the AroG protein with normal, or deleterious morphological changes having a dramatic shift in plant metabolism. Metabolic profiling analysis revealed that the leaves of the transgenic plants had increased levels of phenylalanine (up to 43-fold), tyrosine (up to 24-fold) and tryptophan (up to 10-fold) compared to control plants having an empty vector (EV) and wild type (WT) plants. The significant increase in phenylalanine was accompanied by higher levels of metabolites that belong to the phenylpropanoid pathway. AroG plants showed improved tolerance to salt stress but not to oxidative or drought stress. The most significant improved tolerance was to P. aegyptiaca. Unlike WT/EV plants that were heavily infected by the parasite, the transgenic AroG plants strongly inhibited P. aegyptiaca development, and only a few stems of the parasite appeared above the soil. This delayed development of P. aegyptiaca could be the result of higher accumulation of several phenylpropanoids in the transgenic AroG plants and in P. aegyptiaca, that apparently affected its growth. These findings indicate that high levels of AAAs and their related metabolites have the potential of controlling the development of parasitic plants.

Egyptian broomrape sucrose metabolism in response to different host plants

AbstractBroomrapes are important parasitic weeds in many vegetable crops in dry and warm regions of the world. The study of weed parasite physiology will increase knowledge of broomrape‐host interactions that may be applied to the development of improved parasitic plant control programmes. In this study, developmental patterns of activities of essential enzymes (sucrose synthase [SUS], mannose 6‐phosphate reductase [M6PR], cell wall invertase [CWI] and soluble acid invertase [SAI]) involved in Egyptian broomrape osmoregulation were investigated using three hosts (celery, tomato and cucumber). The earliest broomrape emergence occurred on cucumber; however, the total biomass of the parasite did not differ between cucumber and tomato. The reducing sugars content, gene expression and enzyme activity in the parasite significantly varied with the parasite organs and the hosts. Maximum SAI activity was observed in the apical part (AP) of the flowering shoot of parasite growing on cucumber. However, the peak of genes expression occurred in the same organ across the three hosts, for example SAI1 was expressed maximally in tubercle bearing the flowering shoot (Tub‐FS). The largest amount of reducing sugars was observed in the AP of the parasite grown on tomato. High M6PR activity in the parasite and its matching with M6PR transcriptional levels in three hosts are deemed promising for broomrape management through the deployment of the proteinaceous inhibitors or gene silencing constructs in host plants. Overall, the results indicated that differences in sugar metabolism of Egyptian broomrape grown on different hosts can potentially be exploited for effective management of this difficult‐to‐control parasite.

Herbicides’ efficacy on Egyptian broomrape (Orobanche aegyptiaca Pers.) in tomato and brinjal in South-West Haryana, India

Egyptian broomrape (Orobanche aegyptiaca Pers.) is the most troublesome root holoparasitic weed which causes severe damage to tomato and brinjal crops grown in Mewat and Bhiwani areas of Haryana. A study was conducted to test the efficacy and selectivity of two sulfonylurea herbicides, viz. sulfosulfuron and ethoxysulfuron, and neem cake; pendimethalin in combination with metalaxyl along with sulfonylurea herbicides for managing O. aegyptiaca in tomato and brinjal in field conditions. The post-emergence application (PoE) of sulfosulfuron and ethoxysulfuron at 50 g/ha 30, 60, 90 DAP (days after planting) were more selective to tomato and to control the parasite, O. aegyptiaca, more effectively with average yield increase of 51.7% over untreated check. Neem cake or metalaxyl were not effective to inhibit the growth of O. aegyptiaca in brinjal. It is inferred from this study that ethoxysulfuron at 25 g/ha PoE at 30 DAP and at 50 g/ha or sulfosulfuron at 50 g/ha PoE at 30 and 60 DAP, provided 85–90% control of O. aegyptiaca in tomato. Both the herbicides caused phytotoxicity to brinjal. The results of eight adaptive on-farm trials conducted in tomato during 2016–17 also revealed 92.3% control of O. aegyptiaca with a yield increase of 30.8% over untreated control.

The problem of Orobanche spp. and Phelipanche spp. and their management in Iran

AbstractBroomrape species (Orobanche spp. and Phelipanche spp.) pose a tremendous threat to economically important crops in Iran; however, there is little information on the country’s major broomrape species, their distribution and host ranges, and the subsequent crop losses they cause. The literature from Iran describes Egyptian broomrape (Orobanche aegyptiaca Pers.), hemp broomrape (Orobanche ramosa L.), Phelipanche nana (Reut.) Beck, and Orobanche cumana Wallr. as the major species of broomrape infesting agricultural fields. Solanaceae crops are among the most susceptible crops to infestation by broomrape in the country, and farmers are either shifting production to crops with lesser value or abandoning crop production entirely. Among infested crops, tomato (Solanum lycopersicum L.) is the most susceptible and widely infested, resulting in annual crop yield reductions of up to 40%. Chick pea (Cicer arietinum L.) and canola (Brassica napus L.) are also highly susceptible to broomrape infestation. Current control methods (physical, agronomical, biological, and chemical) have not proven to be effective or economic. The microscopic size of broomrape seeds and the presence of a wide range of host plants (weeds and crops) have promoted the spread of broomrape to new areas of Iran. Hence, the familiarization of farmers with the biology of broomrape would be highly effective in finding suitable control measures and in preventing its further distribution.

Simulating sulfosulfuron fate in soil under different weather scenarios to support weed management decisions.

Residual herbicides are an important component in many weed control strategies. Their herbicidal activity depends on their fate in soil, with respect to the required concentration for weed control in space and time. In this study, the effect of weather conditions on sulfosulfuron fate in soil, following pre-planting incorporation, and the predicted control efficacy of Egyptian broomrape in tomato, were analyzed for two sites using simulations in Hydrus-1D modeling software. Simulated concentration was compared to measured data from field experiments. Model evaluation against measured data from two fields, with weakly alkaline clay soils, showed high correlations between simulated and measured sulfosulfuron concentrations (r = 0.98 and 0.89). The ratio of measured to simulated concentration was relatively low (1.03) at the top 10-cm layer, in which the mean measured concentration was high (29.6 ng g-1 ). This ratio was higher (12.5) at the 30-60 cm depth, in which the mean measured concentration was lower (0.3 ng g-1 ). Simulations of sulfosulfuron fate in each site, using weather data from the years 2009 to 2019, revealed substantial variations in transport patterns. Thirty days after treatment, 16 out of the 22 years simulated for the two sites (11 at each site) resulted in concentrations lower than the critical value for Egyptian broomrape control throughout the soil profile. The data indicates that variation in sulfosulfuron fate is mainly due to differences in the cumulative precipitation. According to simulation results, cumulative precipitation above 20 or 10 mm during the first 10 or 20 days after treatment, respectively, is expected to reduce the efficiency of broomrape control. Considering weather effects when planning herbicide application could optimize herbicide use efficiency. A decision-support tool is presented, whose factors are the time gap and precipitation amount between sulfosulfuron application and tomato planting.

Physiological and growth responses of cucumber (Cucumis sativus L.) genotypes to Egyptian broomrape (Phelipanche aegyptiaca (Pers.) Pomel) parasitism

Lack of consensus on effective approaches for Egyptian broomrape (Phelipanche aegyptiaca) management in host plants has focused attention on the identification of resistant or tolerant genotypes by evaluating plant physiological responses to parasitism. In the current study, the response of 35 cucumber (Cucumis sativus L) genotypes to Egyptian broomrape parasitism was investigated in a completely randomized design with 4 replications. Parasitism by Egyptian broomrape led to a significant decrease in shoot and root dry weight of C. sativus compared to the control treatment which varied across different genotypes. Parasitism resulted in significant but variable increases in hydrogen peroxide, malondialdehyde, protein and phenolic compound content across all genotypes. Catalase-specific activity, ascorbate peroxidase and peroxidase in Egyptian broomrape-infected treatments also differed to that in control treatments. In addition, underground attachments number plant−1 (UAN), emerged spikes number plant−1 (ESN), total attachment number plant−1 (TAN), attachment dry weight (g)/plant−1 (ADW) were significantly different among various cucumber genotypes. As a result of our analysis, genotypes were classified into four clusters. The Khassib greenhouse genotype was different to other genotypes with increases in total phenolic compound content and catalase activity being higher compared to the other three clusters. At the same time, shoot dry weight losses, malondialdehyde enhancement and UAN traits in Khassib had the lowest values compared to the other genotypes when parasitized by broomrape.

A Two-Year Simulated Crop Rotation Confirmed the Differential Infestation of Broomrape Species in China Is Associated with Crop-Based Biostimulants

In Yanqi County of Xinjiang Uygur Autonomous Region, China, broomrape species (Orobanche cumana Wallr and Phelipanche aegyptiaca Pers.) contribute to significant losses of processing tomato and sunflower. During the past decades, a significant infestation pattern was observed between these broomrape species with no scientific peer-reviewed explanation. A two-year pot experiment simulating the crop rotation and an independent hydroponic experiment were performed to address the problem and indicate the main reason behind the differential infestation pattern. Different varieties of three crops (sugar beet, pepper, and wheat) were grown in rotation with tomato and sunflower to identify a crop-rotation induced control mechanism on these two broomrape species. Germination bioassays were performed in vitro to identify stimulation of plant biochemicals collected as methanolic shoots/roots extracts and root exudates on the germination patterns of broomrape seeds. Results indicated that sunflower broomrape soil seed banks reduced during the two-year crop rotation; however, Egyptian broomrape seed banks did not alter and the resulting parasitism significantly reduced tomato growth. Seed germination bioassays confirmed that the methanolic shoot/root extracts successfully stimulate sunflower broomrape seeds germination but fail to stimulate Egyptian broomrape seeds germination. Root exudates collected from hydroponically grown crops also confirmed differential germination patterns in both broomrape species. Current results are of vital importance to explain the control effect of a crop rotation system and moreover, lay the foundation to study the genetic evolution of broomrape species that results in their differential germination responses to natural stimuli.

Effects of N fertilizer and a bioherbicide on Egyptian broomrape (Orobanche aegyptiaca) in a tomato field

This study aimed to investigate the effects of nitrogen fertilizer and a bioherbicide on Egyptian broomrape in a tomato research field at College of Agriculture, Shiraz University, Shiraz, Iran in 2014. Treatments consisted of several levels of nitrate ammonium including 0, 100, 200 and 300 kg ha-1 and a biofertilizer as the first factor and how to use the bioherbicide including soaking seedling roots in bioherbicide, bioherbigation and no bioherbicide application (control) as the second factor. Application of 200 kg ha-1 nitrate ammonium reduced broomrape height and biomass up to 18.7 and 33.7 %, respectively. It increased tomato yield up to 26.8%. Bioherbigation also caused a significant decrease in broomrape height and dry biomass by 44.5 and 58.6 %, respectively. Our results showed that application of 200 kg ha-1 nitrate ammonium along with the bioherbicide can be a promising strategy to decrease the detrimental impact of broomrape and to increase tomato yield.

Induction of systemic resistance in tomato against broomrape (Phelipanche aegyptiaca)

AbstractRhizosphere dwelling bacteria can increase plant resistance to biotic and abiotic stresses, and they promote plant growth through various mechanisms. In this study, three bioassays were conducted including the following: (a) screening for effective bacterial isolates in the suppression of broomrape, (b) evaluating induced systemic resistance against broomrape and (c) comparing the selected bacterium isolate with plant chemical inducers. Fifteen plant growth‐promoting rhizobacteria (PGPR) were examined to assess their biocontrol potential against Egyptian broomrape (Phelipanche aegyptiaca). Ten isolates significantly reduced the broomrape biomass compared to the control. The Lysinibacillus boronitolerans B124 reduced the dry weight of broomrape plants from 2.15 g in control to 0.45 g. Bacillus megaterium B6 was the best isolate in reducing the number of broomrape tubercles. In addition, the activity of three selected bacterial isolates was investigated in induced systemic resistance to broomrape by split‐root method. The Bacillus pumilus INR7 reduced the number of visible broomrape tubercles by 90%, and B. megaterium B71 and L. boronitolerans B124 were the next two in rank. Compared with the control, L. boronitolerans B124 reduced the dry weight of broomrape from 1.49 g in control to 0.39 g. In a subsequent experiment, L. boronitolerans B124 was evaluated along with some resistance‐inducing volatile compounds. Lysinibacillus boronitolerans B124 decreased the number of broomrapes by 87% on average, while the lowest dry weight of broomrape was observed in methyl jasmonate treatment. In conclusion, PGPR have considerable potential to be used in the integrated management of broomrape. It is also possible to use a mixture of rhizobacteria and defence inducers, such as biogenic volatiles as a promising approach in the management of this noxious parasitic weed.

Developmental patterns of enzyme activity, gene expression, and sugar content in sucrose metabolism of two broomrape species

A better understanding of broomrape physiological features opens up new perspectives for developing specific management strategies. For this purpose, activities of key enzymes involved in osmoregulation (SAI1, CWI, M6PR, and SUS1) were considered at developmental stages of two important broomrape species (Egyptian and branched broomrape) on tomato. While Egyptian broomrape tubercles had high activities of invertases, branched broomrape shoots revealed high activities of M6PR and SUS1 during both pre- and post-emergence stages except for M6PR at post-emergence stages of P. aegyptiaca. Interestingly, the main accumulation of total reducing sugars was detected in tubercle during pre- and in shoot during post-emergence. Unlike low levels of genes expression (except for CWI) before parasite emergence, significantly higher expression levels of SAI1, SUS1 and M6PR were detected after parasite emergence. Matching the expression levels of SAI1 and SUS1 genes with their corresponding enzymes activities makes them as the suitable candidates for gene silencing strategies.

Morphological traits and resistance to Egyptian broomrape weed (Orobanche aegyptiaca Pers.) in tobacco under greenhouse condition

Broomrape ('Orobanche aegyptiaca' Pers.) is a debilitating holoparasiting weed in tobacco ('Nicotiana tabacum' L.) fields with devastating effects on its production. In this study, the reaction of 26 tobacco genotypes was evaluated against broomrape weed in randomized complete block design with three replications under greenhouse condition. Tobacco genotypes were planted in both non-inoculated and inoculated conditions where the soil of inoculated pots was mixed with 0.06 g of broomrape seed. The genotype by trait (GT) biplot explained 66% of the total variation of the standardized data and the polygon view of GT presented for 11 traits showed 5 vertex genotypes. Genotype G20 was the best in terms of leaf properties (length, width, number and area), and stem girth while G14 was the best genotype against broomrapes number as well as fresh and dry weight of broomrapes. Genotype G4 was identified for good performance in plant height and fresh weight total while G19 and G26 were best genotypes in terms of total fresh weight. Based on vector view biplot, a strong positive association among leaf properties, number of broomrapes, fresh and dry weight of broomrapes, and among plant height, fresh weight and dry weight of leaf yield were detected. According to ideal genotype biplot, genotype G20 followed by G3, G13 and G24 were the most favourable genotypes regarding all of the measured traits. The plant height, leaf number per plant and stem girth could be considered as effective selection criteria evolving high yielding genotypes. Finally, genotypes G26 and G19 are good candidates for improving most of the measured traits and for obtaining resistance to the Egyptian broomrape.

Efficacy of different chemical and non chemical approaches for management of Broomrape in Indian Mustard

Indian mustard (Brassica juncea) is infested with a parasitic weed, Egyptian broomrape (Phelipancheaegyptiaca), threatening its production in south-western parts ofHaryana. Afield experiment was conducted to study the effect of broomrape control treatments on the growth rate, number of days to 50% flowering and siliqua initiation, primary branches, secondary branches and grain yield of Indian mustard. The crop growth rate, number of primary and secondary branches and the grain yield were higher when supplied with 125% of recommended fertilizer (N & P) + foliar spray of glyphosate at 25 and 50 g/ha + 1.0% solution of (NH4)2SO4 at 25 and 55 DAS, respectively. This was followed by foliar spray of glyphosate at 25 and 50 g/ha + 1.0% (NH4)2SO4 at 25 and 55 DAS, respectively. The broomrape control treatments had no significant effect the relative growth rate and number of days to 50% flowering.

Application Timing and Degradation Rate of Sulfosulfuron in Soil Co-affect Control Efficacy of Egyptian broomrape (Phelipanche aegyptiaca) in Tomato

AbstractEgyptian broomrape (Phelipanche aegyptiacaPers.) is a root-parasitic weed that severely damages many crops worldwide, including tomato (Solanum lycopersicumL.). In Israel, the management protocol used forP. aegyptiacain open-field tomato includes PPI sulfosulfuron at 37.5 g ai ha−1to the top 10-cm soil layer. The objective of this study was to investigate the co-effect of sulfosulfuron application timing and variable degradation rate in soil on the control efficacy ofP. aegyptiacain tomato. Degradation of sulfosulfuron (80ng g−1soil) at a temperature of 15C, measured in soil samples from three farms using liquid chromatography–tandem mass spectrometry, followed a first-order kinetics with variable degradation rate constant among sites (0.008 to 0.012 d−1). Incubation at 25 C increased sulfosulfuron degradation rate constant by a factor of 2 to 2.7 in soils from the different sites, with a similar degradation rate order among soils. A higher degradation rate in the soil resulted in a shorter period of residual activity, measured using a sorghum [Sorghum bicolor(L.) Moench.] bioassay.Phelipanche aegyptiacamanagement in open-field tomatoes was investigated in five independent field experiments. Sulfosulfuron soil concentration throughout the growing season (following preplant incorporation of 37.5 g ha−1) was calculated from laboratory-measured degradation rates, which were corrected to represent the effect of recorded temperatures at each field. At the end of the tomato growing season, control efficacy ofP. aegyptiacavaried among experiments (70.4% to 100%) and positively correlated with predicted sulfosulfuron concentration at the critical period for seedling control (R2=0.67). The current study confirms that sulfosulfuron is degraded in soil to nonphytotoxic metabolites and that rapid degradation rates would result in reduced injury toP. aegyptiacaseedling and, consequently, lower control efficacy.