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Results of previous research on chemigated imazamox for control of branched broomrape (Phelipanche ramosa) in processing tomatoes suggested potential soil-type differences in imazamox availability. Over two years, there were differences in crop-injury between two sites less than 30-km apart: imazamox-treated tomatoes in the Davis location had relatively minor early season injury while tomatoes at the Woodland location were severely injured or killed. The following study was conducted to investigate imazamox sorption in four California soils to determine if differences in herbicide adsorption played a role in variable crop-injury observed in the field trials. To determine the sorption capacity of imazamox of each soil, a batch-equilibrium study was conducted. There were significant differences in sorbed imazamox: the clay soil had the highest adsorption (Robert's Island: 742.5 pg µL−1 sorbed), followed by the sandy loam soil (Ripon: 723.9 pg µL−1 sorbed), while the loam soils from both trial sites (Davis: 704.2 pg µL−1 sorbed; Woodland: 699.9 pg µL−1 sorbed) had the lowest adsorption and were not significantly different from one another. Results from this study illustrate only minor differences in imazamox adsorption among the soils tested which suggests that soil type was likely not a major factor contributing to differences in crop-injury. [ABSTRACT FROM AUTHOR]

The increasing vegetable production in Van/Türkiye province and its districts, where the study was carried out. The most significant of these issues is the parasitic and highly invasive broomrapes. A survey was conducted in AugustOctober 2019 in order to determine the extent of the broomrape problem in the areas of vegetables. In this study, the type of broomrape found in vegetable areas was identified first, then the infestation rates and the average number of shoots in each plant were determined. The results concluded that the branched broomrape [Phelipanche ramosa (L.) Pomel] was found as a single species in all areas. It was also detected that branched broomrape was infested with tomato, eggplant, cucumber, and summer squash; with related densities of 4.2, 0.4, 0.26, and 0.78 %, on average, respectively. No infestation was encountered in pepper. As a result of the study, this infestation detected in summer squash is the first record in terms of the host series of branched broomrape. Although less infestation was seen in other areas, it is predicted that the branched broomrape could be spread rapidly to non-infested areas over time due to its character. [ABSTRACT FROM AUTHOR]

Broomrapes (Orobanche and Phelipanche spp.) are non-achlorophyllous parasitic plants belonging to the Orobanchaceae family, with some species evolving to infest agricultural crops, causing substantial economic losses. This study focuses on Orobanche and Phelipenche species prevalent in Tunisia, particularly Orobanche crenata, Orobanche foetida and Phelipanche ramosa, which pose a significant threat to legume crops and other agronomically important plants. These parasitic species cause severe damage before their aboveground appearance, making early detection and management crucial. Successful breeding programs targeting their hosts necessitate a comprehensive understanding of the genetic variability within different broomrape populations. A plethora of molecular markers, including RAPD, ISSR, AFLP, SSR and SNPs, were employed to evaluate the genetic diversity of Orobanche spp., mainly in Mediterranean countries. This research seeks to analyze the genetic variability and structure of thirty-four (34) Tunisian Orobanche and Phelipanche populations infesting various crops and wild plants. The results demonstrated a higher genetic differentiation within populations rather than between populations and no clear differentiation based on the geographic origins of the populations. By measuring the genetic diversity of a large number of broomrape populations that affect both wild species and crops, this study aims to support efforts toward establishing effective management approaches. [ABSTRACT FROM AUTHOR]

Broomrapes (Orobanche and Phelipanche spp.) are non-achlorophyllous parasitic plants belonging to the Orobanchaceae family, with some species evolving to infest agricultural crops, causing substantial economic losses. This study focuses on Orobanche and Phelipenche species prevalent in Tunisia, particularly Orobanche crenata, Orobanche foetida and Phelipanche ramosa, which pose a significant threat to legume crops and other agronomically important plants. These parasitic species cause severe damage before their aboveground appearance, making early detection and management crucial. Successful breeding programs targeting their hosts necessitate a comprehensive understanding of the genetic variability within different broomrape populations. A plethora of molecular markers, including RAPD, ISSR, AFLP, SSR and SNPs, were employed to evaluate the genetic diversity of Orobanche spp., mainly in Mediterranean countries. This research seeks to analyze the genetic variability and structure of thirty-four (34) Tunisian Orobanche and Phelipanche populations infesting various crops and wild plants. The results demonstrated a higher genetic differentiation within populations rather than between populations and no clear differentiation based on the geographic origins of the populations. By measuring the genetic diversity of a large number of broomrape populations that affect both wild species and crops, this study aims to support efforts toward establishing effective management approaches.

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Summary : Strigolactones (SLs) are a family of terpenoid allelochemicals that were recognized as plant hormones only a decade ago. They influence a myriad of both above‐ and below‐ground developmental processes, and are an important survival strategy for plants in nutrient‐deprived soils. A rapidly emerging approach to gain knowledge on hormone signaling is the use of traceable analogs. A unique class of labeled SL analogs was constructed, in which the original tricyclic lactone moiety of natural SLs is replaced by a fluorescent cyanoisoindole ring system. Biological evaluation as parasitic seed germination stimulant and hypocotyl elongation repressor proved the potency of the cyanoisoindole strigolactone analogs (CISAs) to be comparable to the commonly accepted standard GR24. Additionally, via a SMXL6 protein degradation assay, we provided molecular evidence that the compounds elicit SL‐like responses through the natural signaling cascade. All CISAs were shown to exhibit fluorescent properties, and the high quantum yield and Stokes shift of the pyrroloindole derivative CISA‐7 also enabled in vivo visualization in plants. In contrast to the previously reported fluorescent analogs, CISA‐7 displays a large similarity in shape and structure with natural SLs, which renders the analog a promising tracer to investigate the spatiotemporal distribution of SLs in plants and fungi. Significance Statement: A highly active, labeled strigolactone analog was developed, containing a fluorescent cyanopyrroloindole core as replacement of the original tricyclic lactone moiety. The biological activity as well as in vivo visibility of the tracer were demonstrated in plants, validating its applicability in studies regarding the spatiotemporal distribution of strigolactones in living organisms. [ABSTRACT FROM AUTHOR]

Abstract Root exudates from Lotus japonicus were found to contain at least three different hyphal branching-inducing compounds for the arbuscular mycorrhizal (AM) fungus Gigaspora margarita , one of which had been previously identified as (+)-5-deoxystrigol (5DS), a canonical strigolactone (SL). One of the two remaining unknown hyphal branching inducers was purified and named lotuslactone. Its structure was determined as methyl (E)-2-(3-acetoxy-2-hydroxy-7-methyl-1-oxo-1,2,3,4,5,6-hexahydroazulen-2-yl)-3-(((R)-4-methyl-5-oxo-2,5-dihydrofuran-2-yl)oxy)acrylate, by 1D and 2D NMR spectroscopy, and HR-ESI- and EI-MS. Although lotuslactone, a non-canonical SL, contains the AB-ring and the enol ether-bridged D-ring, it lacks the C-ring and has a seven-membered cycloheptadiene in the A-ring part as in medicaol, a major SL of Medicago truncatula. Lotuslactone was much less active than 5DS, but showed comparable activity to methyl carlactonoate (MeCLA) in inducing hyphal branching of G. margarita. Other natural non-canonical SLs including avenaol, heliolactone, and zealactone (methyl zealactonoate) were also found to be moderate to weak inducers of hyphal branching in the AM fungus. Lotuslactone strongly elicited seed germination in Phelipanche ramosa and Orobanche minor , but Striga hermonthica seeds were 100-fold less sensitive to this stimulant. Graphical abstract The model legume Lotus japonicus was shown to produce both a canonical and a non-canonical strigolactones as rhizosphere signals. Image 1 Highlights • A novel strigolactone, named lotuslactone, was isolated from Lotus japonicus. • Lotuslactone is a non-canonical strigolactone. • Lotuslactone is a moderate inducer of hyphal branching in Gigaspora margarita. • Lotuslactone is a strong inducer of seed germination in root parasitic plants. [ABSTRACT FROM AUTHOR]

Phelipanche and Orobanche spp. (broomrapes) are economically important parasitic weeds, causing severe damage to many agricultural crops. However, conventional methods to control these parasitic weeds are often not effective. Targeting molecular and biochemical processes involved in the establishment of the connection between the parasite and the host may offer a new perspective for control. However, progress in the understanding of these processes is hampered by the fact that genetic transformation and regeneration of these parasites is difficult if not impossible due to their specific lifecycle. Phelipanche and Orobanche spp. are holoparasites that need to attach to the roots of a host plant to get their assimilates, nutrients and water to develop and reproduce. The present study describes a highly efficient genetic transformation and regeneration protocol for the root holoparasitic Phelipanche ramosa. We present a new transformation system for P. ramosa using Agrobacterium rhizogenes MSU440 carrying a non-destructive selection marker gene coding for a red fluorescent protein (DsRed1). Using this protocol up to 90% transformation efficiency was obtained. We transformed 4 weeks old P. ramosa calli and transgenic calli expressing DsRed1 were then cultured on host plants. For the first time, we present shoot and flower development of the transgenic parasitic plant P. ramosa after successful connection of transgenic calli with the host plant roots. Moreover, we also present, for the first time, growth and development of P. ramosa shoots and flowers in vitro in the absence of a host plant. [ABSTRACT FROM AUTHOR]

Phelipanche ramosa (L) Pomel is a root holoparasitic weed for many crops, particularly for the processing tomato in Italy. In order to integrate the use of chemical methods to control P. ramosa (L.), there has been an increased effort to research alternative methods using natural compounds. In this regard, two experimental trials were set up in an open field in Foggia (southern Italy) during the 2016 spring-summer seasons. The first trial compared two tomato seedling transplanting dates to evaluate the effects on emerged shoots of P. ramosa. The second trial compared six organic compounds added to the soil to control P. ramosa: olive-mill wastewater and five commercial products (Allyl Isothiocyanate®, Alfaplus®, Radicon®, Rhizosum Max®, and Kendal Nem®). An untreated control was also included. The numbers of P. ramosa emerged shoots (branched plants) were significantly lower for the late tomato seedling transplanting date than for the earlier one. All of the organic products tested that were applied to the soil, particularly olive-mill wastewater, Alfaplus®, Rhizosum Max®, and Kendal Nem®, showed a significant reduction of the P. ramosa infestation of the tomato crop with respect to the untreated control, with a positive effect on the productive parameters. [ABSTRACT FROM AUTHOR]

Integrated crop protection tolerates residual weed floras if they are not harmful for crop production. These weeds can host harmful crop pests, among which parasitic plants such as branched broomrape ( Phelipanche ramosa ). This holoparasite is responsible for large yield losses in French crops such as oilseed rape. To date, there are no herbicides available to control it. To evaluate ex ante the impact of crop management practices on weed-mediated parasite infection of crops, we developed an indicator calculated from outputs of the weed dynamics model F lor S ys . It consists of three components assessing weed impact on (1) stimulation of parasite germination during the whole cropping season, i.e. the potential risk reduction for future crops via a reduction of the parasite seed bank, (2) the stimulation of parasite germination in host crops, i.e. the potential risk increase for the current crop, (3) parasite reproduction on weed plants, i.e. the potential risk increase for future crops. This indicator was then used to predict weed-mediated broomrape risk in cropping systems from six regions from France and one from Spain. Antagonisms and synergies with other indicators of weed-harmfulness for crop production and weed contribution to plant and functional biodiversity were investigated with Pearson correlation analyses. For instance, cropping systems with a high parasite risk also had a high functional biodiversity (e.g. weed-based food offer for bees). Effects of crop management practices on the weed-mediated parasite risk indicator were identified with linear models; regression trees were used to identify the combinations of management practices that maximised or minimised weed-mediated broomrape risk. Parasite risk depended on crop rotation, sowing and harvest dates, tillage, herbicides and mechanical weeding. The lowest risk was observed in fields that were last tilled less than 21 days before sowing, with more than 0.6 herbicides per year (i.e. 3 applications in 5 years) with multiple entry modes into the weeds (e.g. leaves and roots) and the last herbicide sprayed no later than 127 days before harvest. RLQ analyses were used to identify correlations between weed species traits (Q matrix) and simulated parasite risk (R matrix), via simulated weed densities (L matrix). Early summer-emerging weed species increased parasite risk. No other notable correlations were found, indicating that parasite risk results from a weed community of interacting species, and not simply from individual weed species. An advice table was built to summarize and explain the effects of crop management practices on weed-mediated parasite risk. [ABSTRACT FROM AUTHOR]

The present research investigated the efficacy and the selectivity of three sulfonylureas (SUs) rimsulfuron (RS), chlorsulfuron (CS) and triasulfuron (TS) for Phelipanche ramosa control in processing tomato. In 2014 a single dose (D) (75, 15 and 22.5 g ha–1 active ingredient – a.i.– of RS, CS and TS, respectively), split into three applications at equal rate, was delivered into the soil layer interested by the roots using two herbigation methods i) through the drip irrigation system (DH) or ii) by foliar spray followed by overhead irrigation (FH). In 2015 SUs were applied in pre-transplant at one third of D, and in post-transplant at the dose D, at onehalf and at one-fourth of D, delivered in 3 rates by drip herbigation. In both experiments RS gave the best broomrape control and the highest yield increase compared with the untreated crop and CS improved crop yield similarly to RS despite being less effective in contrasting branched broomrape, In 2014, the foliar application of TS and CS resulted in plant injuries which, more significantly with TS, caused lower numbers and fresh weight of fruits as well as a lower crop productivity increase. In the same year the drip herbigation with TS resulted in the lowest broomrape control and tomato yield increase. In 2015, the best parasite control and tomato yield performances were obtained with RS and CS when applied in pre-transplant at 25.0 and 5.0 g ha–1 a.i., respectively, and in post-transplant at 75.0 and 15.0 g ha–1 a.i., respectively. With TS, the pre-transplant application a.i. was the most effective among the TS treatments resulting in a yield improvement similar to RS and CS, while it was confirmed the low broomrape control when applied through drip irrigation due to its low mobility in the soil. More research is needed in order to better exploit the combination of pre- and post-transplant applications in the chemical control of P. ramosa of tomato under the conditions in southern Italy.

Phelipanche ramosa is a parasitic plant that infects numerous crops worldwide. In Western Europe it recently expanded to a new host crop, oilseed rape, in which it can cause severe yield losses. We developed 13 microsatellite markers for P. ramosa using next-generation 454 sequencing data. The polymorphism at each locus was assessed in a sample of 96 individuals collected in France within 6 fields cultivated with tobacco, hemp or oilseed rape. Two loci were monomorphic. At the other 11 loci, the number of alleles and the expected heterozygosity ranged from 3 to 6 and from 0.31 to 0.60, respectively. Genetic diversity within each cultivated field was very low. The host crop from which individuals were collected was the key factor structuring genetic variation. Individuals collected on oilseed rape were strongly differentiated from individuals collected on hemp or tobacco, which suggests that P. ramosa infecting oilseed rape forms a genetically diverged race. The microsatellites we developed will be useful for population genetics studies and for elucidating host-associated genetic divergence in P. ramosa.

The present research investigated the efficacy and the selectivity of three sulfonylureas (SUs) rimsulfuron (RS), chlorsulfuron (CS) and triasulfuron (TS) for Phelipanche ramosa control in processing tomato. In 2014 a single dose (D) (75, 15 and 22.5 g ha-1 active ingredient - a.i.- of RS, CS and TS, respectively), split into three applications at equal rate, was delivered into the soil layer interested by the roots using two herbigation methods i) through the drip irrigation system (DH) or ii) by foliar spray followed by overhead irrigation (FH). In 2015 SUs were applied in pre-transplant at one third of D, and in post-transplant at the dose D, at onehalf and at one-fourth of D, delivered in 3 rates by drip herbigation. In both experiments RS gave the best broomrape control and the highest yield increase compared with the untreated crop and CS improved crop yield similarly to RS despite being less effective in contrasting branched broomrape, In 2014, the foliar application of TS and CS resulted in plant injuries which, more significantly with TS, caused lower numbers and fresh weight of fruits as well as a lower crop productivity increase. In the same year the drip herbigation with TS resulted in the lowest broomrape control and tomato yield increase. In 2015, the best parasite control and tomato yield performances were obtained with RS and CS when applied in pre-transplant at 25.0 and 5.0 g ha-1 a.i., respectively, and in post-transplant at 75.0 and 15.0 g ha-1 a.i., respectively. With TS, the pre-transplant application a.i. was the most effective among the TS treatments resulting in a yield improvement similar to RS and CS, while it was confirmed the low broomrape control when applied through drip irrigation due to its low mobility in the soil. More research is needed in order to better exploit the combination of pre- and post-transplant applications in the chemical control of P. ramosa of tomato under the conditions in southern Italy. [ABSTRACT FROM AUTHOR]

The effects of salinity stress on growth parameters and the activities of antioxidant enzymes (superoxide dismutase (SOD), peroxidase (POX), catalase (CAT), glutathione reductase (GR), and ascorbate peroxidase (APX)) were investigated in Arabidopsis thaliana during Phelipanche ramosa mediated biotic stress. The experiment was conducted using 100 mM NaCl on infected 18-dayold A. thaliana plants in Gamborg B5 medium. P. ramosa infection reduced root length and shoot dry weight (DW) in A. thaliana. After salt stress treatment shoot fresh weight (FW) decreased in A. thaliana plants infected with P. ramosa. Salt stress treatment produced a significant reduction in carotenoid and total chlorophyll content while it did not change the chl a/b ratio of infected plants. POX and APX activities increased during P. ramosa infection in A. thaliana. Additional NaCl treatment decreased the level of lipid peroxidation accompanied by an increment in SOD, POX, GR, CAT and APX activities, while chl a/b ratio and total chl content decreased. These results, presented for the first time, demonstrated induction of the antioxidant defense system against P. ramosa infection by NaCl treatment in A. thaliana. [ABSTRACT FROM AUTHOR]

The root-parasitic weed Phelipanche ramosa (L.) Pomel represents a major problem for processing tomato crops. The control of this holoparasitic plant is difficult, and better understanding of treatment methods is needed to develop new and specific control strategies. This study investigated 12 agronomic, chemical, biological and biotechnological strategies for the control of this parasitic weed, in comparison with the untreated situation. The trial was carried out in 2014 at the Department of Agriculture, Food and the Environment of the University of Foggia (southern Italy), using processing tomato plants grown in pots filled with soil from a field that was heavily infested with P. ramosa. After transplantation, top dressing was performed with 70 kg ha–1 nitrogen. A randomised block design with 3 replicates (pots) was adopted. During the growing cycle of the tomato, at 70, 75, 81 and 88 days after transplantation, the number of parasitic shoots (branched plants) that had emerged in each pot was determined, and the leaf chlorophyll of the plants was measured using a soil-plantanalysis- development meter. At harvesting on 8 August 2014, the major quanti-qualitative yield parameters were determined, including marketable yield, mean weight, dry matter, soluble solids, and fruit colour. The results show lower chlorophyll levels in the parasitised tomato plants, compared to healthy plants. None of the treatments provided complete control against P. ramosa. However, among the methods tested, Radicon® biostimulant (Radicon, Inc., Elk Grove Village, IL, USA), compost activated with Fusarium oxysporum, nitrogen and sulphur mineral fertilisers, EnzoneTM soil fumigant (Elliott Chemicals Ltd., Auckland, New Zealand), and a resistant tomato genotype mitigated the virulence of the attacks of this parasite. These effects should be improved by combining some of these treatments, especially for gradual and continued reduction in the seed bank of the parasite in the soil. For the tomato yields across the different treatments, there were no significant differences seen; however, the yields showed an improving trend for treatments with lower presence of the P. ramosa weed.

Phelipanche ramosa (L) Pomel is a root holoparasitic weed for many crops, particularly for the processing tomato in Italy. In order to integrate the use of chemical methods to control P. ramosa (L.), there has been an increased effort to research alternative methods using natural compounds. In this regard, two experimental trials were set up in an open field in Foggia (southern Italy) during the 2016 spring–summer seasons. The first trial compared two tomato seedling transplanting dates to evaluate the effects on emerged shoots of P. ramosa. The second trial compared six organic compounds added to the soil to control P. ramosa: olive-mill wastewater and five commercial products (Allyl Isothiocyanate®, Alfaplus®, Radicon®, Rhizosum Max®, and Kendal Nem®). An untreated control was also included. The numbers of P. ramosa emerged shoots (branched plants) were significantly lower for the late tomato seedling transplanting date than for the earlier one. All of the organic products tested that were applied to the soil, particularly olive-mill wastewater, Alfaplus®, Rhizosum Max®, and Kendal Nem®, showed a significant reduction of the P. ramosa infestation of the tomato crop with respect to the untreated control, with a positive effect on the productive parameters.

Phelipanche ramosa (L.) Pomel (branched broomrape) is a holoparasitic plant that reproduces on crops and also on weeds, which contributes to increase the parasite seed bank in fields. This parasite extracts all its nutrients at the host's expense so that host-parasite trophic relationships are crucial to determine host and parasite growth. This study quantified the intensity with which P. ramosa draws assimilates from its host and analyzed whether it varied with host species, host phenological stage and host growth rate. A greenhouse experiment was conducted on three host species: the crop species Brassica napus (L.) (oilseed rape) and two weed species, Capsella bursapastoris (L.) Medik. and Geranium dissectum (L.). Plants were grown with or without P. ramosa and under three light levels to modulate host growth rate. The proportion of host biomass loss due to parasitism by P. ramosa differed between host species (at host fructification, biomass loss ranged from 34 to 84%). B. napus and C. bursa-pastoris displayed a similar response to P. ramosa, probably because they belong to the same botanical family. The sensitivity to P. ramosa in each host species could be related to the precocity of P. ramosa development on them. Host compartments could be ranked as a function of their sensitivity to parasitism, with the reproductive compartment being the most severely affected, followed by stems and roots. The proportion of biomass allocated to leaves was not reduced by parasitism. The proportion of pathosystem biomass allocated to the parasite depended on host species. It generally increased with host stage progression but was constant across light induced-host growth rate, showing that P. ramosa adapts its growth to host biomass production. The rank order of host species in terms of sink strength differed from that in terms of host sensitivity. Finally, for B. napus, the biomass of individual parasite shoots decreased with increasing their number per host plant, regardless of host growth rate. Results will be incorporated into a mechanistic model in order to analyze the effect of parasitic plant species on weed community assembly and to design new cropping systems for controlling P. ramosa. [ABSTRACT FROM AUTHOR]

The root-parasitic weed Phelipanche ramosa (L.) Pomel represents a major problem for processing tomato crops. The control of this holoparasitic plant is difficult, and better understanding of treatment methods is needed to develop new and specific control strategies. This study investigated 12 agronomic, chemical, biological and biotechnological strategies for the control of this parasitic weed, in comparison with the untreated situation. The trial was carried out in 2014 at the Department of Agriculture, Food and the Environment of the University of Foggia (southern Italy), using processing tomato plants grown in pots filled with soil from a field that was heavily infested with P. ramosa. After transplantation, top dressing was performed with 70 kg ha-1 nitrogen. A randomised block design with 3 replicates (pots) was adopted. During the growing cycle of the tomato, at 70, 75, 81 and 88 days after transplantation, the number of parasitic shoots (branched plants) that had emerged in each pot was determined, and the leaf chlorophyll of the plants was measured using a soil-plantanalysis- development meter. At harvesting on 8 August 2014, the major quanti-qualitative yield parameters were determined, including marketable yield, mean weight, dry matter, soluble solids, and fruit colour. The results show lower chlorophyll levels in the parasitised tomato plants, compared to healthy plants. None of the treatments provided complete control against P. ramosa. However, among the methods tested, Radicon® biostimulant (Radicon, Inc., Elk Grove Village, IL, USA), compost activated with Fusarium oxysporum, nitrogen and sulphur mineral fertilisers, EnzoneTM soil fumigant (Elliott Chemicals Ltd., Auckland, New Zealand), and a resistant tomato genotype mitigated the virulence of the attacks of this parasite. These effects should be improved by combining some of these treatments, especially for gradual and continued reduction in the seed bank of the parasite in the soil. For the tomato yields across the different treatments, there were no significant differences seen; however, the yields showed an improving trend for treatments with lower presence of the P. ramosa weed. [ABSTRACT FROM AUTHOR]

In France, oilseed rape is getting highly infected since 1990 by the branched broomrape Phelipanche ramosa (L.) Pomel. Branched broomrape infection causes serious yield losses ranging from 5 to 100 %, notably in the Mediterranean area. P. ramosa is parasiting the plant roots. The growth of P. ramosa on Brassicaceae weeds has not been studied quantitatively so far, except for the model species Arabidopsis thaliana. Since P. ramosa has a fast development rate on the fast-growing A. thaliana, P. ramosa development should be slower on other slower-growing Brassicaceae species. Here, we cultivated in the laboratory seven Brassicaceae weed species including Capsella bursa- pastoris, Capsella rubella, Cardamine hirsuta, Lepidium campestre, Lepidium draba, Sinapis arvensis and A. thaliana as control, during 3 weeks. We counted the number of P. ramosa individuals that have reached the following growth stages: germination, attachment, tubercle, bud and underground stem. We then assessed the development rate of P. ramosa by calculating the odds ratio of attachment or higher development stages of P. ramosa on Brassicaceae, with A. thaliana as the reference. We found that five Brassicaceae species had an odds ratio ranging from 0.9 to 2.4. These ratios are thus similar or higher than that of the A. thaliana reference. This finding shows for the first time that P. ramosa develops faster on the five Brassicaceae species. This finding is also unexpected because A. thaliana is a fast-growing plant, whereas the five Brassicaceae species have a longer life cycle. Therefore, this observation demonstrates for the first time that P. ramosa development depends on others factors than the speed of plant host development. [ABSTRACT FROM AUTHOR]

Cucumber (Cucumis sativus) plants were found to exude at least 12 germination stimulants for root parasitic weeds including 5 known strigolactones, 7-oxoorobanchol, 7-oxoorobanchyl acetate, orobanchol, orobanchyl acetate, and 4-deoxyorobanchol. Two novel germination stimulants were purified from cucumber root exudates and their structures were determined to be 7α-and 7β-hydroxyorobanchyl acetate by 1D and 2D NMR spectroscopy, and ESI- and EI-MS spectrometry. The stereochemistry was determined by NOE measurement and by comparing the CD spectra with those of the synthetic standards of four stereoisomers of orobanchol. 7α- and 7β-Hydroxyorobanchol were detected by LC-MS/MS, and GC-MS analysis of purified sample confirmed their structures. The germination stimulation activities of 7α- and 7β-hydroxyorobanchyl acetate on Orobanche minor were comparable to those of orobanchyl acetate and 7-oxoorobanchyl acetate. By contrast, 7β-hydroxyorobanchyl acetate was a highly potent germination stimulant for Phelipanche ramosa inducing more than 50% germination at 10 pM. [ABSTRACT FROM AUTHOR]

Highlights: [•] Allelopathic grass Avena strigosa produces no known strigolactones. [•] Avenaol is a C20 germination stimulant structurally related to strigolactones. [•] Avenaol is more active on Phelipanche ramosa, but less active on Striga hermonthica and Orobanche minor. [Copyright &y& Elsevier]

Abstract: Dazomet (Basamid®) is a dry powder formulation that releases the toxic gas methyl isothiocyanate for the control of soil borne pests and weed seeds when applied to moist soils. We evaluated its efficacy for destroying Phelipanche mutelii (branched broomrape) seed banks. Dazomet is typically used where effectiveness can be improved with the addition of water but we examined its performance in soils with low moisture content in container experiments and field trials. In containers, less than 10% of P. mutelii seed remained viable 30 days after dazomet applications of 112.8–338.4 kg ha−1 at soil moisture content from 0.05 to 0.15 g g−1. Seeds buried at a depth of 5 cm needed to be in contact with the product for longer than one week before viability was affected. An initial field trial did not detect a decline in seed viability 7 days after dazomet application. Viability assessments in a second field trial were made 30 days after dazomet application with an airseeder at a rate of 338.4 kg ha−1. Less than 10% of P. mutelii seeds at a depth of 5 cm survived and dazomet was as effective as two other soil fumigants, methyl bromide and a methyl iodide/chloropicrin mixture. The release of methyl isothiocyanate is reduced in soils in containers with low soil moisture content but occurs over a long time period. Methyl isothiocyanate dissipated more rapidly in soils in containers with higher soil moisture content and at lower dazomet application rates. A higher application rate is required in the field to ensure the dazomet powder is evenly distributed through the soil profile and there is adequate methyl isothiocyanate resident in the top soil layer to achieve seed kill. This has consequences for plant back times in fumigated land following dazomet application. [Copyright &y& Elsevier]

Phelipanche ramosa is a parasitic plant that infects numerous crops worldwide. In Western Europe it recently expanded to a new host crop, oilseed rape, in which it can cause severe yield losses. We developed 13 microsatellite markers for P. ramosa using next-generation 454 sequencing data. The polymorphism at each locus was assessed in a sample of 96 individuals collected in France within 6 fields cultivated with tobacco, hemp or oilseed rape. Two loci were monomorphic. At the other 11 loci, the number of alleles and the expected heterozygosity ranged from 3 to 6 and from 0.31 to 0.60, respectively. Genetic diversity within each cultivated field was very low. The host crop from which individuals were collected was the key factor structuring genetic variation. Individuals collected on oilseed rape were strongly differentiated from individuals collected on hemp or tobacco, which suggests that P. ramosa infecting oilseed rape forms a genetically diverged race. The microsatellites we developed will be useful for population genetics studies and for elucidating host-associated genetic divergence in P. ramosa. [ABSTRACT FROM AUTHOR]

Abstract: Plants defend themselves against virus/viroid infection by induction of a mechanism of viral RNA degradation or translation inhibition. This is achieved by the production of small RNAs referred to as small interfering RNAs and microRNA, the key molecules in establishment of RNA directed silencing. Potato Spindle Tuber Viroid (PSTVd) was the first viroid species to be identified as naturally infecting potato, and it was found to infect many other crop species, wild and ornamental plants. Recently the experimental host range of PSTVd was extended with the root non-photosynthetic parasitic weed - Phelipanche ramosa (L) Pomel. Here we examined the small RNA population in P. ramosa infected with PSTVd and we observed the presence of PSTVd derived small RNAs. The hotspot regions for production of those PSTVd specific small RNAs were defined by their mapping on the viroid genome sequence. Further, we evaluated the expression levels of selected conserved microRNA families in the viroid infected P. ramosa. Upon infection, two members of miRNA395 family were significantly accumulated, while several members of miRNA390, miRNA396, miRNA319, miRNA166, miRNA167 and miRNA159 were strongly down-regulated. All these findings imply the involvement of various small RNA classes in the P. ramosa response to PSTVd infection. [Copyright &y& Elsevier]

Der Hanf-Blauwürger, auch Ästige Sommerwurz genannt, Phelipanche ramosa (= Orobanche ramosa) hat als einzige Art der Gattung Phelipanche ein größeres Wirtspflanzenspektrum und ist weltweit verbreitet. Phelipanche ramosa gilt in Österreich, bis auf ein Vorkommen in Kärnten, als ausgestorben. Im Juli 2010 konnte erstmals in Österreich an Tomaten im geschützten Anbau Phelipanche ramosa nachgewiesen werden.

Background: Some root-parasitic plants belonging to the Orobanche, Phelipanche or Striga genus represent one of the most destructive and intractable weed problems to agricultural production in both developed and developing countries. Compared with most of the other weeds, parasitic weeds are difficult to control by conventional methods because of their life style. The main difficulties that currently limit the development of successful control methods are the ability of the parasite to produce a tremendous number of tiny seeds that may remain viable in the soil for more than 15 years. Seed germination requires induction by stimulants present in root exudates of host plants. Researches performed on these minute seeds are until now tedious and time-consuming because germination rate is usually evaluated in Petri-dish by counting germinated seeds under a binocular microscope. Results: We developed an easy and fast method for germination rate determination based on a standardized 96- well plate test coupled with spectrophotometric reading of tetrazolium salt (MTT) reduction. We adapted the Mosmann's protocol for cell cultures to germinating seeds and determined the conditions of seed stimulation and germination, MTT staining and formazan salt solubilization required to obtain a linear relationship between absorbance and germination rate. Dose-response analyses were presented as applications of interest for assessing half maximal effective or inhibitory concentrations of germination stimulants (strigolactones) or inhibitors (ABA), respectively, using four parameter logistic curves. Conclusion: The developed MTT system is simple and accurate. It yields reproducible results for germination bioassays of parasitic plant seeds. This method is adapted to high-throughput screenings of allelochemicals (stimulants, inhibitors) or biological extracts on parasitic plant seed germination, and strengthens the investigations of distinctive features of parasitic plant germination. [ABSTRACT FROM AUTHOR]

Abstract: Phelipanche ramosa (broomrape) is a root-holoparasitic angiosperm that attacks a wide number of annual crops. According to the host, the duration of its life cycle can range from 14 weeks (on tomato/tobacco) to 40 weeks (on oilseed rape). We conducted a cross-infection experiment to evaluate the intensity and kinetics of infection of broomrape populations. Two parasitic populations, P-long collected on oilseed rape and P-short collected on tobacco, were cultivated on two crops (their natural and outsider hosts). After, 4, 8, 12 and 16 weeks, the intensity of infection and the distribution of developmental stages (fixation to fructification) of broomrape were determined. The two broomrape populations showed distinct patterns of intensity and kinetics of infectivity. P-long showed a higher infection success in the early stages than P-short. Both parasitic populations showed a higher aggressiveness on their natural hosts than on outsider hosts. Only the P-short population completed its life cycle on the two hosts, and with similar development rates on both hosts, while the P-long population was unable to complete its life-cycle during the 16 weeks of the experiment. It is suggested that the shift in host specificity that allowed P. ramosa to infect oilseed rape in recent times has led to a divergence of pathovars having different life-cycle durations. [Copyright &y& Elsevier]

Abstract: (+)-Strigone was described earlier in a paper on isolation of strigol and then recently examined for hyphal branching activity in arbuscular mycorrhizal fungi as a strigolactone. Herein, it was isolated from root exudates of Houttuynia cordata, and its structure was confirmed by direct comparison with synthetic standards in LC–MS/MS, GC–MS, and 1H and 13C NMR analyses. The stereochemistry of strigone was determined by comparing the CD spectra and RR t in chiral LC–MS/MS with those of synthetic (+)-strigone and (−)-strigone. Four stereoisomers of strigone exhibited clearly different levels of stimulation activity on the seeds of three root parasitic plants, Orobanche minor, Phelipanche ramosa, and Striga hermonthica. (+)-Strigone was a highly potent germination stimulant on S. hermonthica and also on P. ramosa, but less active than ent-2′-epi-strigone on O. minor. In addition to strigone, H. cordata was found to produce strigol, sorgomol, and 5-deoxystrigol, indicating that this plant produces mainly strigol-type strigolactones derived from 5-deoxystrigol. [Copyright &y& Elsevier]

Abstract: Over the past decade, Phelipanche ramosa, a weedy parasitic plant (broomrape), has been increasingly infesting winter oilseed rape (WOSR) fields in France. Elite WOSR lines have shown different responses in P. ramosa infested fields, suggesting that genetic variability might be available for breeding programmes targeting broomrape resistance. Ten WOSR genotypes selected for their contrasting response in field experiments were analysed using mini-rhizotron and greenhouse co-culture experiments to determine the components of resistance to broomrape. Partial resistance was revealed at three developmental stages of the parasitic plant. First, at the germination stage, parasite attachment to the roots of some WOSR lines was limited and associated with a low rate of parasite seed germination. This mechanism of parasite avoidance could nevertheless be suppressed under high infestation in mini-rhizotron and greenhouse conditions. Second, at the root attachment stage, limited parasite attachment was observed in mini-rhizotron conditions under low and high infestation, and in greenhouse conditions. Third, after successful parasite attachment, some WOSR genotypes retarded and even disturbed the growth of tubercles, minimising and delaying parasite emergence from the soil. Although the exact mechanisms limiting parasite attachment and tubercle development require further investigation, our findings suggest that, by cumulating various resistance traits in new genotypes to enhance effectiveness and potential durability of resistance, breeding could be a promising control strategy in WOSR. [Copyright &y& Elsevier]

After a conditioning period, seed dormancy in obligate root parasitic plants is released by a chemical stimulus secreted by the roots of host plants. Using Phelipanche ramosa as the model, experiments conducted in this study showed that seeds require a conditioning period of at least 4 d to be receptive to the synthetic germination stimulant GR24. A cDNA-AFLP procedure on seeds revealed 58 transcript-derived fragments (TDFs) whose expression pattern changed upon GR24 treatment. Among the isolated TDFs, two up-regulated sequences corresponded to an abscisic acid (ABA) catabolic gene, PrCYP707A1, encoding an ABA 8'-hydroxylase. Using the rapid amplification of cDNA ends method, two full-length cDNAs, PrCYP707A1 and PrCYP707A2, were isolated from seeds. Both genes were always expressed at low levels during conditioning during which an initial decline in ABA levels was recorded. GR24 application after conditioning triggered a strong up-regulation of PrCYP707A1 during the first 18h, followed by an 8-fold decrease in ABA levels detectable 3 d after treatment. In situ hybridization experiments on GR24-treated seeds revealed a specific PrCYP707A1 mRNA accumulation in the cells located between the embryo and the micropyle. Abz-E2B, a specific inhibitor of CYP707A enzymes, significantly impeded seed germination, proving to be a non-competitive antagonist of GR24 with reversible inhibitory activity. These results demonstrate that P. ramosa seed dormancy release relies on ABA catabolism mediated by the GR24-dependent activation of PrCYP707A1. In addition, in situ hybridization corroborates the putative location of cells receptive to the germination stimulants in seeds.Abbreviations:ABAabscisic acidAbzabscinazoleAECadenylate energy chargeAFLPamplified fragment length polymorphismRACErapid amplification of cDNA endsSLstrigolactoneTDFtranscript-derived fragment [ABSTRACT FROM PUBLISHER]

Abstract: The phasing out of methyl bromide as a fumigant has prompted a search for possible alternatives. Here, the relative efficacy of soil solarization and fumigation with chloropicrin and 1,3-dichloropropene (CP+1,3-D) was evaluated in greenhouse-grown tomatoes. Experiments were conducted over two seasons in southern Italy, aimed at evaluating the effects of soil treatment on soil-borne pest control, and the vegetative growth and fruit production of tomato. Solarization provided a better level of control over the major fungal pathogens (Fusarium oxysporum f. sp. lycopersici and f. sp. radicis lycopersici, as well as Pyrenochaeta lycopersici) than CP+1,3-D fumigation. Solarization was also more effective in reducing the population of Meloidogyne spp. in the soil, and was particularly valuable for the suppression of the parasitic plant branched broomrape Phelipanche ramosa (syn. Orobanche ramosa). In both seasons, solarization was more beneficial than CP+1,3-D fumigation in terms of plant growth and crop productivity. In conclusion, solarization provided a good level of control over some important tomato pests and weeds, while at the same time improving the productivity in an environmentally friendly manner. It should therefore represent a viable alternative to methyl bromide fumigation for the greenhouse production of tomato. [Copyright &y& Elsevier]