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Orobanche crenata is a root holoparasite that depends on its host for nutritional requirements. The shikimate pathway that metabolizes about 30% of the assimilated carbon in photosynthetic plants plays a role in host-parasite relationships. Aromatic amino acids (AAAs) and phenolic acids are derived from the shikimate pathway and serve as precursors of a wide number of primary and secondary metabolites. The effects of the O. crenata parasite on the phenolic acid and AAA profiles of two faba bean varieties and the differences of these compounds between the host organs and attached parasite at infestation stages were studied. Hosts and attached parasites were collected and divided, depending on the stage of parasite development, into four stages. The results revealed that phenolic acids and free AAAs tended to increase in parasitized roots compared to those of healthy roots, and the greatest increase in phenolic contents occurred at the first infestation stage. Syringic acid was observed to be unique to the parasite. Profiles of phenolic acids and AAAs were changed during the developmental stages of the parasite and differed from those of its host. Caffeic in the parasite reached more than 100 times that in Nubaria 4 host roots at the fourth infestation stage. Free phenylalanine in the parasite ranged between 2.2 and 5.5 times its level in host roots at all infestation stages. This study provides much evidence that indicates O. crenata is able to self-regulate its phenolic and AAA metabolites during its developmental stages, which differ from those of its host. [ABSTRACT FROM AUTHOR]

This study investigated the potential of endophytic fungi as biocontrol agents against Orobanche infestations in fruit crops such as chickpea, soybean, lentil, and pea plants from different sites in Ika agricultural habitats in Delta State, Nigeria, using appropriate standard methods. Fusarium sp. showed significant inhibition of Orobanche crenata (75%) by mycotoxin production and Penicillium sp. (65%) by biocombustion. Field trials showed a significant reduction in Orobanche-infested areas, with Fusarium sp. (40% to 10%) and Penicillium sp. (30% to 10%) treatments showing significant yield improvement (20% and 22%, respectively). The study concluded that selected fungi, especially Fusarium sp. and Penicillium sp., are effective control agents for Orobanche in legume crops. This information contributes to sustainable agriculture by providing environmentally friendly alternatives to pesticides, crop yields, and economic losses from plants, and it reduces the incidence of pests. [ABSTRACT FROM AUTHOR]

Rafflesia is an endangered endophytic holoparasitic plant that lives the majority of its life inside the tissues of its sole plant host, Tetrastigma. Rafflesia floral buds emerge to produce the world's largest single flower. Like other plants, holoparasites harbor a diverse microbiome, the role(s) of which has remained largely unstudied. We characterized the bacterial microbiome of seeds of Rafflesia speciosa and cuttings of its host. We found evidence that R. speciosa seed has similar bacterial profiles to its infected host, which suggests that seeds sequester certain host bacteria, as well as acquire unique bacterial taxa from biotic associates of the fruit. We did not find evidence of mycorrhizal taxa in the microbiome. This is the first study of the microbial endophytes associated with any Rafflesia species and its host, a tripartite holobiont, and provides insights on its cryptic microbial partners. We discuss how this may aid horticultural propagation of Rafflesia. [ABSTRACT FROM AUTHOR]

Based on extensive studies of specimens in various herbaria, lectotypes are designated for many taxa of holoparasitic Orobanchaceae. In total, 31 names in the genera Alectra, Boschniakia, Cistanche, Orobanche, Phelipanche and Phelypaea are lectotypified and type references are provided for 46 names. All types are illustrated by scanned images. The following new names are proposed due to rank changes: Orobanche amoena var. dzejveri, O. amoena var. regeliana, Orobanche camptolepis f. sideana, Orobanche lutea var. hians, Phelipanche arenaria var. sareptana, Phelipanche caesia var. acuminata, Phelipanche caucasica, Phelipanche lavandulacea var. serratocalyx, Phelipanche pulchella var. bungeana, Phelipanche purpurea var. hirsutaand Phelipanche purpurea var. iberica. The following names are synonymized: Orobanche arenaria f. personata, Orobanche borkhausenii, Orobanche caesia f. tomentosa, Orobanche caryophyllacea f. besseri, Orobanche cernua f. subgrandis, Orobanche cumana f. helianthi, Orobanche eriophora, Orobanche glaucantha, Orobanche heyniae, Orobanche psilostemon, Orobanche sideritidis and Phelypaea helenae. [ABSTRACT FROM AUTHOR]

This study investigated the potential of endophytic fungi as biocontrol agents against Orobanche infestations in fruit crops such as chickpea, soybean, lentil, and pea plants from different sites in Ika agricultural habitats in Delta State, Nigeria, using appropriate standard methods. Fusarium sp. showed significant inhibition of Orobanche crenata (75%) by mycotoxin production and Penicillium sp. (65%) by biocombustion. Field trials showed a significant reduction in Orobanche-infested areas, with Fusarium sp. (40% to 10%) and Penicillium sp. (30% to 10%) treatments showing significant yield improvement (20% and 22%, respectively). The study concluded that selected fungi, especially Fusarium sp. and Penicillium sp., are effective control agents for Orobanche in legume crops. This information contributes to sustainable agriculture by providing environmentally friendly alternatives to pesticides, crop yields, and economic losses from plants, and it reduces the incidence of pests.

ABSTRACTRafflesia is an endangered endophytic holoparasitic plant that lives the majority of its life inside the tissues of its sole plant host, Tetrastigma. Rafflesia floral buds emerge to produce the world’s largest single flower. Like other plants, holoparasites harbor a diverse microbiome, the role(s) of which has remained largely unstudied. We characterized the bacterial microbiome of seeds of Rafflesia speciosa and cuttings of its host. We found evidence that R. speciosa seed has similar bacterial profiles to its infected host, which suggests that seeds sequester certain host bacteria, as well as acquire unique bacterial taxa from biotic associates of the fruit. We did not find evidence of mycorrhizal taxa in the microbiome. This is the first study of the microbial endophytes associated with any Rafflesia species and its host, a tripartite holobiont, and provides insights on its cryptic microbial partners. We discuss how this may aid horticultural propagation of Rafflesia.

Parasitic weeds in the genera Orobanche, Phelipanche (broomrapes) and Striga (witchweeds) have a devastating impact on food security across much of Africa, Asia and the Mediterranean Basin. Yet, how climatic factors might affect the range expansion of these weeds in the context of global environmental change remains unexplored. We examined satellite‐based environmental variables such as surface temperature, root zone soil moisture, and elevation, in relation to parasitic weed distribution and environmental conditions over time, in combination with observational data from the Global Biodiversity Information Facility (GBIF). Our analysis reveals contrasting environmental and altitude preferences in the genera Striga and Orobanche. Asiatic witchweed (Striga asiatica), which infests corn, rice, sorghum, and sugar cane crops, appears to be expanding its range in high elevation habitats. It also shows a significant association with heat‐moisture coupling events, the frequency of which is rising in such environments. These results point to geographical shifts in distribution and abundance in parasitic weeds due to climate change. [ABSTRACT FROM AUTHOR]

Background: Orobanche is an obligate parasite on faba bean in the Mediterranean region, causes considerable yield losses. Breeding tolerant faba bean genotypes to Orobanche is pivotal to sustain production and ensuring global food security, particularly considering the challenges posed by population growth. In the present study, seven faba bean lines and four testers were used in a line×tester mating design during 2020–2021 and 2021–2022 growing seasons. The eleven parents and their 28 F1 crosses were evaluated under Orobanche free and naturally infested soils. Results: The results demonstrated considerable variations among the evaluated genotypes, wide diversity among the parental materials, and heterotic effects for all studied agronomic traits under Orobanche-free and infested soils. Orbanche infestation displayed a significant adverse impact on all the studied agronomic traits. The genotypes Line1, Line2, Line3, and Line5 displayed superior performance under Orobanche-infested conditions and recorded the highest values of all studied agronomic traits. Additionally, Line1, Line2, Line3, Line5, and Line7 exhibited desirable significant GCA for most evaluated traits under the two infestation conditions. The obtained crosses displayed significant negative or positive heterosis for studied agronomic characters such as plant height, number of branches per plant, number of pods per plant, number of seeds per plant, and seed weight per plant were observed. Furthermore, specific cross combinations such as Line2×Sakha3, Line3×Nubaria5, Line7 × Nubaria5, Line6×Nubaria1, Line5×Sakha3, Line1×Sakha3, and Line1 × Nubaria5 exhibited superior performance in seed yield and contributing traits under Orobanche-infested conditions. Moreover, these specific crosses showed superior efficacy in reducing dry weight of Orobanche spikes. The results obtained from GGE biplot analysis closely aligned with those from the line×tester procedure, affirming the significance of GGE biplot as a valuable statistical tool for assessing genotype combining ability in line× tester data. Both additive and non-additive gene actions were reported to be predominantly involved in the inheritance of the studied agronomic traits in faba bean. Conclusions: The detected genetic diversity within the evaluated faba bean genotypes and their developed crosses exhibits substantial potential for improving faba bean productivity under Orobanche-infested conditions. The parental genotypes, Line1, Line2, Line3, Line5, and Line7, were identified as effective and promising combiners. Moreover, the developed crosses Line2×Sakha3, Line3×Nubaria5, Line7×Nubaria5, Line6×Nubaria1, Line5×Sakha3, Line1×Sakha3, and Line1×Nubaria5 could be considered valuable candidates for developing high-yielding and tolerant faba bean genotypes to Orobanche. [ABSTRACT FROM AUTHOR]

The plant Centaurea cineraria L. subsp. cineraria has been investigated as a potential source of inhibitors of broomrape radicle growth. The latter are weeds that pose a threat to agriculture and for which there are few methods available for the control of infestations. Four sesquiterpene lactones have been isolated from C. cineraria L. subsp. cineraria aerial parts and identified as isocnicin, cnicin, salonitenolide, and 11β,13-dihydrosalonitenolide using spectroscopic, spectrometric, and optical methods. Salonitenolide and 11β,13-dihydrosalonitenolide have been isolated for the first time from this plant. Tested at 1.0–0.1 mM against the broomrape species Phelipanche ramosa, Orobanche minor, Orobanche crenata, and Orobanche cumana, isocnicin, cnicin, and salonitenolide demonstrated remarkable inhibitory activity (over 80% in most of the cases) at the highest concentrations. Structure-activity relationship conclusions indicated the significance of the α,β-unsaturated lactone ring. In addition, the synthetic acetylated derivative of salonitenolide showed the strongest activity among all compounds tested, with inhibitions close to 100% at different concentrations, which has been related to a different lipophilicity and the absence of H-bond donor atoms in its structure. Neither the extracts nor the compounds exhibited the stimulating activity of broomrape germination (induction of suicidal germination). These findings highlight the potential of C. cineraria to produce bioactive compounds for managing parasitic weeds and prompt further studies on its sesquiterpene lactones as tools in developing natural product-based herbicides. [ABSTRACT FROM AUTHOR]

Grain and forage legumes are important sources of food and feed, key for sustainable agriculture given the environmental services they provide. However, their cultivation is hampered in the Mediterranean Basin and Near East by the widespread occurrence of the root parasitic weed crenate broomrape (Orobanche crenata). Other broomrape species such as O. minor, O. foetida, and Phelipanche aegyptica are also of local importance. As for other parasitic weeds, a number of management strategies have been proposed, but considering that temperate legumes in the area are low-input crops, these strategies are largely uneconomical or hard to achieve, leaving the use of resistant cultivars as the most desirable option. Breeding for broomrape resistance is not an easy task, but significant progress has been achieved by classical breeding and selection and will profit from recent developments in phenomics and genomics. Here, achievements and prospects in broomrape management and resistance breeding are presented and critically discussed. [ABSTRACT FROM AUTHOR]

Abstract Parasitic weeds in the genera Orobanche, Phelipanche (broomrapes) and Striga (witchweeds) have a devastating impact on food security across much of Africa, Asia and the Mediterranean Basin. Yet, how climatic factors might affect the range expansion of these weeds in the context of global environmental change remains unexplored. We examined satellite‐based environmental variables such as surface temperature, root zone soil moisture, and elevation, in relation to parasitic weed distribution and environmental conditions over time, in combination with observational data from the Global Biodiversity Information Facility (GBIF). Our analysis reveals contrasting environmental and altitude preferences in the genera Striga and Orobanche. Asiatic witchweed (Striga asiatica), which infests corn, rice, sorghum, and sugar cane crops, appears to be expanding its range in high elevation habitats. It also shows a significant association with heat‐moisture coupling events, the frequency of which is rising in such environments. These results point to geographical shifts in distribution and abundance in parasitic weeds due to climate change.

Broomrapes (Orobanche spp.) are root parasitic plants that threaten agricultural production in many parts of the world. In this study, the effect of two orobanche species, Orobanche crenata and O. foetida, on faba bean plants was studied in Tunisia. The two orobanche species inhibited both biomass production and pod formation, decreased the chlorophyll (Chl) content and total lipid (TL), and enhanced electrolyte leakage (EL) and lipid peroxidation. Concomitantly, orobanche parasitism induced a lower degree of fatty acid (FA) unsaturation due to a shift in the FA composition. On the other hand, with regard to orobanche seeds, oleic and linoleic acids were the predominant FA in the two orobanche species. After orobanche seed germination and penetration of host tissues, all the orobanche development stages showed a decrease in the TL content and changes in the FA composition in comparison to orobanche seeds. The level of TL was equal to or lower in all parasite development stages (except for S4) than that in the roots and leaves of healthy faba bean plants. These results suggest that the negative effect of orobanche infestation on faba bean development can be attributed to the reduced chlorophyll content and alteration in membrane stability attested by the reduced TL level and FA unsaturation. [ABSTRACT FROM AUTHOR]

Broomrapes (Orobanche and Phelipanche spp.) rely on the presence of a host plant for nourishment. Based on the release of specific molecules by the crop plant, their seeds germinate and eventually establish a vascular connection with host roots through a haustorium. Therefore, they deprive their hosts of water and nutrients, posing a severe threat to vegetable and legume crops worldwide. Due to their growth behaviour, amount and longevity of seeds released, and, generally, a large variety of hosts, the control of parasitic plants is rather difficult. In this review, we give an update about agronomic and genetic approaches controlling host-parasite interactions. Management of broomrapes in vegetables and legumes relies on different approaches: trap and catch crops; suicidal germination by strigolactones (SLs), analogues and mimics; SL degradation; biological and chemical control; other control methods. Further, the production of resistant cultivars is highly desirable. Some natural sources of resistance have been identified in landraces and wild relatives of vegetable and legume crops. Additional variability has been discovered by artificial mutagenesis, but it has been poorly exploited for breeding commercial cultivars. Recent genomic knowledge in parasitic and host species opens new perspectives for the comprehension of molecular bases of interaction and applied breeding, using molecular assisted breeding and biotechnological approaches aimed to modify genes controlling the various stages of parasitization. Anyway, the combination of different genetic resistance mechanisms with agronomical management practices is mandatory to develop a durable containment strategy.

The plant Centaurea cineraria L. subsp. cineraria has been investigated as a potential source of inhibitors of broomrape radicle growth. The latter are weeds that pose a threat to agriculture and for which there are few methods available for the control of infestations. Four sesquiterpene lactones have been isolated from C. cineraria L. subsp. cineraria aerial parts and identified as isocnicin, cnicin, salonitenolide, and 11β,13-dihydrosalonitenolide using spectroscopic, spectrometric, and optical methods. Salonitenolide and 11β,13-dihydrosalonitenolide have been isolated for the first time from this plant. Tested at 1.0–0.1 mM against the broomrape species Phelipanche ramosa, Orobanche minor, Orobanche crenata, and Orobanche cumana, isocnicin, cnicin, and salonitenolide demonstrated remarkable inhibitory activity (over 80% in most of the cases) at the highest concentrations. Structure-activity relationship conclusions indicated the significance of the α,β-unsaturated lactone ring. In addition, the synthetic acetylated derivative of salonitenolide showed the strongest activity among all compounds tested, with inhibitions close to 100% at different concentrations, which has been related to a different lipophilicity and the absence of H-bond donor atoms in its structure. Neither the extracts nor the compounds exhibited the stimulating activity of broomrape germination (induction of suicidal germination). These findings highlight the potential of C. cineraria to produce bioactive compounds for managing parasitic weeds and prompt further studies on its sesquiterpene lactones as tools in developing natural product-based herbicides.

Broomrapes (Phelipanche aegyptiaca and Orobanche spp.) are obligate plant parasites that cause extreme damage to crop plants. The parasite seeds have strict requirements for germination, involving preconditioning and exposure to specific chemicals strigolactones [SLs] exuded by the host roots. SLs are plant hormones derived from plant carotenoids via a pathway involving the Carotenoid Cleavage Dioxygenase 8 (CCD8). Having no effective means to control parasitic weeds in most crops, and with CRISPR/Cas9 being an effective gene-editing tool, here we demonstrate that CRISPR/Cas9-mediated mutagenesis of the CCD8 gene can be used to develop host resistance to the parasitic weed P. aegyptiaca. Cas9/single guide (sg) RNA constructs were targeted to the second exon of CCD8 in tomato (Solanum lycopersicum L.) plants. Several CCD8Cas9 mutated tomato lines with variable insertions or deletions in CCD8 were obtained with no identified off-targets. Genotype analysis of T1 plants showed that the introduced CCD8 mutations are inherited. Compared to control tomato plants, the CCD8Cas9 mutant had morphological changes that included dwarfing, excessive shoot branching and adventitious root formation. In addition, SL-deficient CCD8Cas9 mutants showed a significant reduction in parasite infestation compared to non-mutated tomato plants. In the CCD8Cas9 mutated lines, orobanchol (SL) content was significantly reduced but total carotenoids level and expression of genes related to carotenoid biosynthesis were increased, as compared to control plants. Taking into account, the impact of plant parasitic weeds on agriculture and difficulty to constitute efficient control methods, the current study offers insights into the development of a new, efficient method that could be combined with various collections of resistant tomato rootstocks.

Broomrapes (Phelipanche aegyptiaca and Orobanche spp.) are obligate plant parasites that cause extreme damage to crop plants. The parasite seeds have strict requirements for germination, involving preconditioning and exposure to specific chemicals strigolactones [SLs] exuded by the host roots. SLs are plant hormones derived from plant carotenoids via a pathway involving the Carotenoid Cleavage Dioxygenase 8 (CCD8). Having no effective means to control parasitic weeds in most crops, and with CRISPR/Cas9 being an effective gene-editing tool, here we demonstrate that CRISPR/Cas9-mediated mutagenesis of the CCD8 gene can be used to develop host resistance to the parasitic weed P. aegyptiaca. Cas9/single guide (sg) RNA constructs were targeted to the second exon of CCD8 in tomato (Solanum lycopersicum L.) plants. Several CCD8Cas9 mutated tomato lines with variable insertions or deletions in CCD8 were obtained with no identified off-targets. Genotype analysis of T1 plants showed that the introduced CCD8 mutations are inherited. Compared to control tomato plants, the CCD8Cas9 mutant had morphological changes that included dwarfing, excessive shoot branching and adventitious root formation. In addition, SL-deficient CCD8Cas9 mutants showed a significant reduction in parasite infestation compared to non-mutated tomato plants. In the CCD8Cas9 mutated lines, orobanchol (SL) content was significantly reduced but total carotenoids level and expression of genes related to carotenoid biosynthesis were increased, as compared to control plants. Taking into account, the impact of plant parasitic weeds on agriculture and difficulty to constitute efficient control methods, the current study offers insights into the development of a new, efficient method that could be combined with various collections of resistant tomato rootstocks.

Orobanche crenata, an obligate holoparasite, causes severe damage to faba bean grown in the Mediterranean region. A greenhouse experiment was conducted to determine and compare the potential of salicylic acid (SA), and acetylsalicylate (AcSA) used as seed soaking (0.5-1.5 mM, each) or foliar spray (2-6 mM, each) to increase faba bean tolerance to Orobanche crenata infection. Under the challenge of Orobanche infection, the application of SA or AcSA enhanced the growth of faba bean plants by improving their viability, height, and fresh and dry weight. SA and AcSA reduced the growth of parasite tubercles and retarded their development to emerged spike, the most harmful stage. AcSA was more effective than SA in increasing faba bean tolerance to O. crenata infection, and seed soaking showed the greatest effect. At 110 days of sowing, soaking seeds in 0.5 or 1 mM AcSA completely prevented the death of infected plants and increased the weight of plants by 22 and 67%, respectively, and pod weight/plant by 512 and 442%. Moreover, these two treatments greatly reduced Orobanche growth, and complete inhibition of tubercles and emerged spikes occurred by soaking seeds in 0.5 mM AcSA. Orobanche infection greatly increased phenolic content and antioxidant activity in the host tissues, but their levels tended to reduce by all salicylate treatments. The results suggest the great potential of soaking host seeds in AcSA, the inexpensive commercial form of SA, can enhance plant resistance against Orobanche parasite.

The stigma is the terminal part of the carpel which receives pollen during the pollination process. Although the role of the stigmas in pollination is the same for all angiosperms, stigmas structures are very diverse. This study aimed to evaluate intraspecific, interspecific and intergeneric stigmas variability and then find differences of the stigma morphology amongst 24 holoparasitic Orobanche and Phelipanche species and provide new insights into its potential taxonomic value. This paper was also focused on selecting the best diagnostic features that would be used for future stigma analysis in other species of Orobanchaceae. These analyses were conducted with fresh, dry and fixed material using stereomicroscopy from different locations from Central Europe. Twenty-one quantitative or qualitative morphological features were analysed. This study highlights the variation of stigma morphology and characters which are useful to improve the taxonomic understanding of problematic taxa. Thus, two main types of stigmas were established, based on tested features: 1–oval, rarely hemispherical in shape, most often one-coloured with lobes separated in Phelipanche stigmas; 2–spherical to hemispherical, rarely oval, multi-coloured with partially fused or separated lobes in Orobanche stigmas. The best diagnostic features of the stigmas for distinguishing the Orobanchaceae are the type and subtype of stigma, the length and area of the stigma, the width of single lobes, the width in the middle part of the stigma, the length of upper and lower separation in the middle part between lobes and the angle between lobes in the upper and lower part. The morphological features of the stigmas are important criteria for distinguishing genera, sections and subsections, as well as related species. In this study, we present the first stigma morphological studies for the most numerous genera from the tribe Orobancheae and this paper may determine features possible to use in solving certain taxonomic problems and evolutionary relationships of the species. [ABSTRACT FROM AUTHOR]

Grain and forage legumes are important sources of food and feed, key for sustainable agriculture given the environmental services they provide. However, their cultivation is hampered in the Mediterranean Basin and Near East by the widespread occurrence of the root parasitic weed crenate broomrape (Orobanche crenata). Other broomrape species such as O. minor, O. foetida, and Phelipanche aegyptica are also of local importance. As for other parasitic weeds, a number of management strategies have been proposed, but considering that temperate legumes in the area are low-input crops, these strategies are largely uneconomical or hard to achieve, leaving the use of resistant cultivars as the most desirable option. Breeding for broomrape resistance is not an easy task, but significant progress has been achieved by classical breeding and selection and will profit from recent developments in phenomics and genomics. Here, achievements and prospects in broomrape management and resistance breeding are presented and critically discussed.

Broomrapes (Orobanche spp.) are root parasitic plants that threaten agricultural production in many parts of the world. In this study, the effect of two orobanche species, Orobanche crenata and O. foetida, on faba bean plants was studied in Tunisia. The two orobanche species inhibited both biomass production and pod formation, decreased the chlorophyll (Chl) content and total lipid (TL), and enhanced electrolyte leakage (EL) and lipid peroxidation. Concomitantly, orobanche parasitism induced a lower degree of fatty acid (FA) unsaturation due to a shift in the FA composition. On the other hand, with regard to orobanche seeds, oleic and linoleic acids were the predominant FA in the two orobanche species. After orobanche seed germination and penetration of host tissues, all the orobanche development stages showed a decrease in the TL content and changes in the FA composition in comparison to orobanche seeds. The level of TL was equal to or lower in all parasite development stages (except for S4) than that in the roots and leaves of healthy faba bean plants. These results suggest that the negative effect of orobanche infestation on faba bean development can be attributed to the reduced chlorophyll content and alteration in membrane stability attested by the reduced TL level and FA unsaturation.

The study of allelopathic activity of plants and the isolation and characterization of the responsible allelochemicals can lead to the development of environment friendly alternative approaches to weed control. Conyza species are invasive weeds that use allelopathic activity as part of a successful strategy to outcompete neighboring plants. Broomrape weeds are parasitic plants that use host-induced germination and the formation of a haustorium as strategies to infect host plants. The control of broomrape infection in most affected crops is limited or non-existing. In the current study, we investigated the allelopathic activity of Conyza bonariensis organic extracts in suicidal germination and radicle growth of four broomrape species (Orobanche crenata, Orobanche cumana, Orobanche minor and Phelipanche ramosa). A bioactivity-driven fractionation of Conyza bonariensis extracts led to the identification of two germination-inducing molecules and two growth-inhibitory compounds. The germination-inducing metabolites had species-specific activity being hispidulin active on seeds of O. cumana and methyl 4-hydroxybenzoate active in P. ramosa. The growth-inhibitory metabolites (4Z)-lachnophyllum lactone and (4Z,8Z)-matricaria lactone strongly inhibited the radicle growth of all parasitic weed species studied. Some structure–activity relationships were found as result of the study herein presented. [ABSTRACT FROM AUTHOR]

The strigolactones (SLs) are plants hormones that have multiple functions in architecture and development. The roles of SLs in shoot branching and stem secondary growth of autotrophic plants are established. SL is also involved in the interaction between root parasitic plants and their host plants. SLs are exudates by the root of the host plant in search of a fungal partner for symbiotic association, while parasitic plants utilize this facility to detect the host root. The first formed tubercle of Philapanhche, whose germinations are driven by host-derived SLs, exudates parasitic derived SLs (PSLs) and could encourages germination of the adjacent parasitic seeds, resulting in parasite cluster formation. The existence of aboveground spikes in clusters suggests an intriguing approach for increasing parasite population by amplifying PSLs, which result in massive parasitic seed germination. PSLs probably have a role in the increased branching of Broomrapes opposing the host plant, resulting in the parasites' clustered appearance aboveground. This review highlights the distinct roles of SLs and PSLs, and their potential role in host-parasitic interaction. [ABSTRACT FROM AUTHOR]

Strigolactones (SLs) are plant hormones that regulate shoot branching. In addition, SLs act as compounds that stimulate the germination of root parasitic weeds, such as Striga spp. and Orobanche spp., which cause significant damage to agriculture worldwide. Thus, SL agonists have the potential to induce suicidal germination, thereby reducing the seed banks of root parasitic weeds in the soil. Particularly, phenoxyfuranone-type SL agonists, known as debranones, exhibit SL-like activity in rice and Striga hermonthica . However, little is known about their effects on Orobanche spp. In this study, we evaluated the germination-inducing activity of debranones against Orobanche minor . Analysis of structure-activity relationships revealed that debranones with electron-withdrawing substituents at the 2,4- or 2,6-position strongly induced the germination of Orobanche minor . Lastly, biological assays indicated that 5-(2-fluoro-4-nitrophenoxy)-3-methylfuran-2(5 H )-one (test compound 61 ) induced germination to a comparable or even stronger extent than GR24, a well-known synthetic SL. Altogether, our data allowed us to infer that this enhanced activity was due to the recognition of compound 61 by the SLs receptor, KAI 2d, in Orobanche minor .

Abstract Background Ascochyta blight caused by Ascochyta fabae Speg. and broomrape (Orobanche crenata) are among the economically most significant pathogens of faba bean. Several QTLs conferring resistance against the two pathogens have been identified and validated in different genetic backgrounds. The aim of this study was to saturate the most stable QTLs for ascochyta and broomrape resistance in two Recombinant Inbred Line (RIL) populations, 29H x Vf136 and Vf6 x Vf136, to identify candidate genes conferring resistance against these two pathogens. Results We exploited the synteny between faba bean and the model species Medicago truncatula by selecting a set of 219 genes encoding putative WRKY transcription factors and defense related proteins falling within the target QTL intervals, for genotyping and marker saturation in the two RIL populations. Seventy and 50 of the candidate genes could be mapped in 29H x Vf136 and Vf6 x Vf136, respectively. Besides the strong reduction of the QTL intervals, the mapping process allowed replacing previous dominant and pedigree-specific RAPD flanking markers with robust and transferrable SNP markers, revealing promising candidates for resistance against the two pathogens. Conclusions Although further efforts in association mapping and expression studies will be required to corroborate the candidate genes for resistance, the fine-mapping approach proposed here increases the genetic resolution of relevant QTL regions and paves the way for an efficient deployment of useful alleles for faba bean ascochyta and broomrape resistance through marker-assisted breeding.

Two field experiments carried out at Sakha Agricultural Research Station Farm, Kafr El-Sheikh Governorate, Egypt, and Agricultural Research Centre during the two growing seasons 2018/2019 and 2019/2020 seasons to evaluate the intercropping of onion, garlic and fenugreek with faba bean crop on broomrape incidence to increase faba bean yield, land usage and economic return in heavy soil infestation of broomrape. Treatments included: faba bean alone (control); faba bean + onion cv. Giza 20; faba bean + garlic cv. Sids 40 and faba bean + fenugreek cv. Giza 2. The experiment was laid out in a RCBD with split arrangements in three replications. Infection treatments were kept in main plots and three crops intercropping with faba bean in subplots. The obtained results showed that number spikes/m² and dry weight of spikes (g/m²) of broom- rap (Orobanche sp) were significantly affected by infection with broomrap (Orobanche sp) and the solid faba bean gave the highest values of plant height, yield and yield components, as seed yield ton/ha, 100 seed weight (g), protein %, number of seeds/plant, number of pods/plant, number of seeds/pod, pod length (cm) and plant height (cm) were significantly affected by intercropping with onion, garlic and fenugreek decreased infestation by broomrap (Orobanche sp) and increased faba bean yield. [ABSTRACT FROM AUTHOR]

Broomrapes (Orobanche and Phelipanche spp.) are root holoparasites deriving their nourishment from the parasitic interaction they establish with the host plant. Vegetable crops are severely affected worldwide from broomrapes infestations, which are hard-to-manage through the conventional agronomical practices and determines relevant production losses. The identification of resistant varieties represents the ideal solution to face with this noxious threat, and several efforts were spent along decades in this perspective. In this review, we give an update about genetic and molecular mechanisms underlying the host-parasite interactions and a comprehensive overview on breeding for resistance to Orobanche and Phelipanche spp. in vegetables. Natural sources of resistance were discovered from germplasm exploration in some species, and artificial mutagenesis provided additional variability. Recent advancements in the genomics of parasitic and host plants, and the availability of new breeding technologies will pave the way for future developments, and valuable results have already been achieved in the last few years. The integration of different genetic resistance mechanisms, preferably interfering with different parasite's developmental stages, with innovative agronomical management practices will probably provide a more effective and durable containment strategy. [ABSTRACT FROM AUTHOR]

Abstract Background The parasitic plant Orobanche cumana is one of the most important threats to sunflower crops in Europe. Resistant sunflower varieties have been developed, but new O. cumana races have evolved and have overcome introgressed resistance genes, leading to the recurrent need for new resistance methods. Screening for resistance requires the phenotyping of thousands of sunflower plants to various O. cumana races. Most phenotyping experiments have been performed in fields at the later stage of the interaction, requiring time and space. A rapid phenotyping screening method under controlled conditions would need less space and would allow screening for resistance of many sunflower genotypes. Our study proposes a phenotyping tool for the sunflower/O. cumana interaction under controlled conditions through image analysis for broomrape tubercle analysis at early stages of the interaction. Results We optimized the phenotyping of sunflower/O. cumana interactions by using rhizotrons (transparent Plexiglas boxes) in a growth chamber to control culture conditions and Orobanche inoculum. We used a Raspberry Pi computer with a picamera for acquiring images of inoculated sunflower roots 3 weeks post inoculation. We set up a macro using ImageJ free software for the automatic counting of the number of tubercles. This phenotyping tool was named RhizOSun. We evaluated five sunflower genotypes inoculated with two O. cumana races and showed that automatic counting of the number of tubercles using RhizOSun was highly correlated with manual time-consuming counting and could be efficiently used for screening sunflower genotypes at the tubercle stage. Conclusion This method is rapid, accurate and low-cost. It allows rapid imaging of numerous rhizotrons over time, and it enables image tracking of all the data with time kinetics. This paves the way toward automatization of phenotyping in rhizotrons that could be used for other root phenotyping, such as symbiotic nodules on legumes.

Broomrape weeds (Orobanche and Phelipanche spp.) are noxious parasites that infect crops using haustoria formed at the tip of their radicles. Dichloromethane extract obtained from the roots of Convolvulus arvensis strongly inhibits the radicle growth of broomrape weeds. A complex mixture of arvensic acids was isolated as the metabolites responsible of the inhibitory activity of C. arvensis extract against broomrape radicle growth via activity-guided fractionation and 1H NMR and ESI MS data. We showed that the exposure of broomrape seedlings to this arvensic acids mixture results in a strong phytotoxic effect on their radicles in four broomrape species infecting a wide range of crops worldwide. This discovery paves the way for the synthesis of new bioherbicides and could contribute to the development of efficient and sustainable management strategies for broomrape weeds, for which control in many crops is limited or non-existing. [ABSTRACT FROM AUTHOR]

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

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

Background and aimsThe broomrapes, Orobanche sensu lato (Orobanchaceae), are common root parasites found across Eurasia, Africa and the Americas. All species native to the western hemisphere, recognized as Orobanche sections Gymnocaulis and Nothaphyllon, form a clade that has a centre of diversity in western North America, but also includes four disjunct species in central and southern South America. The wide ecological distribution coupled with moderate taxonomic diversity make this clade a valuable model system for studying the role, if any, of host-switching in driving the diversification of plant parasites.MethodsTwo spacer regions of ribosomal nuclear DNA (ITS + ETS), three plastid regions and one low-copy nuclear gene were sampled from 163 exemplars of Orobanche from across the native geographic range in order to infer a detailed phylogeny. Together with comprehensive data on the parasites' native host ranges, associations between phylogenetic lineages and host specificity are tested.Key resultsWithin the two currently recognized species of O. sect. Gymnocaulis, seven strongly supported clades were found. While commonly sympatric, members of these clades each had unique host associations. Strong support for cryptic host-specific diversity was also found in sect. Nothaphyllon, while other taxonomic species were well supported. We also find strong evidence for multiple amphitropical dispersals from central North America into South America.ConclusionsHost-switching is an important driver of diversification in western hemisphere broomrapes, where host specificity has been grossly underestimated. More broadly, host specificity and host-switching probably play fundamental roles in the speciation of parasitic plants.

This research aimed to identify the degree of farmers' implementation of Orobranchial integrated control techniques in the old lands at El Behira Governorate, their sources of information, the most important problems facing them, and their suggestions for the advancement of the crop. the 3 largest administrative districts in terms of the area planted with the faba bean in 2021 were selected. These districts were Abu Homs, Adku and Dillingat, in three villages, namely, Tolimbat Bersiq, Debono, and Qamaha. Data were collected from November 2021 to January 2022 using a personal interview questionnaire with 269 respondents. The results showed a low level of respondents' implementation of integrated control techniques. Agricultural control techniques came at the fore, followed by chemical and biological control, whose implementation rate was very low among the respondents. The most important constraints facing implementing these techniques were lack of knowledge about the extension recommendations related to these methods (88.48%) and lack of confidence in the agricultural extension recommendations (85.36%), the absence of the extension role (75.09%), and lack of tools to implement these methods (69.14%). Their most important suggestions were to devise resistance varieties with high productivity to Orobranche (78.81%), set an indicative selling price before planting time (77.32%), support the cooperatives' role by providing production requirements at an appropriate price (75.09%), and apply the contract farming system 64.06%. In the end, the study recommends planning extension programs aimed to learn farmers about integrated control methods for Orobanche and implementing extension activities based on practical clarification in farmers' fields. [ABSTRACT FROM AUTHOR]

The genus Orobanche is mainly distributed in the northern hemisphere and consists of about 170 species. The present study focuses on a cytological study of Korean endangered species Orobanche filicicola and morphologically similar species Orobanche coerulescens and its morphotype, which was previously referred to as O. coerulescens f. alba but was taxonomically treated as a synonym of O. coerulescens. Chromosome numbers of 13 individuals in six populations of two Korean Orobanche taxa (O. coerulescens and O. filicicola) and morphotype of O. coerulescens were examined to understand the karyotype diversity. A chromosome number of 2n = 2x = 38 was uniformly observed for all the Orobanche taxa in Korea despite individuals of two different color types (typical purple and whitish yellow) being included. The karyotypes of O. filicicola were metacentric to submetacentric, and the length of chromosomes ranged from 2.08 to 4.74 μm, resulting in a haploid karyotype length of 60.92 μm. Investigations of meiotic configuration of O. filicicola, O. coerulescens, and its morphotype were constantly stable. In those species, all homologous chromosome pairs have formed regular bivalents as previously documented in other species of the genus Orobanche.

This research aimed to inspect the impacts of severe parasitic plants (Orobache spp.) on grain yield, some quality characteristics, marketing price and profitability loss of red lentil in the major lentil growing area of south-east Anatolia. Farmer field trials were carried out in two neighbouring fields planted with Yerli Kırmızı (landrace) and Firat-87 varieties of lentil employing a split-plot experimental design in the Yollar basi location of Viransehir in the 2018-2019 crop growing season. Lentil varieties were placed into main plots and the broomrape infestations (i.e. 0, 5, 10, and 15 plants m-2) in the subplots respectively. Grain yield, hectolitre weights and 1000-kernel weights and protein contents (%) were scored. All grain samples were presented to randomly chosen grain purchasers in the local commodity market and marketing price offers were scored respectively. Results showed that broomrape infestation from zero to 15 broomrapes m-2 reduced the grain yield significantly from 2033.33 kg ha-1 to 833.33 kg ha-1 by 59%. Although being non-significant, Firat-87 (1512, 5 kg ha-1) was found to be higher yielding than Yerli Kırmızı (1325 kg ha-1). Regression equations between grain yield reductions vs. broomrape infestation ratios turned out to be significant and reliable with high coefficients of determinations for both varieties. Some visual purchasing criteria such as hectolitre and 1000-kernel weights were not affected seriously. Purchasers offered very similar marketing prices for pulse grains with all severity levels. The economic loss was huge ($555 ha-1). Regression equations derived from grain yield vs. infestation densities were found to be reliable with high coefficients of determinations and can be perfectly used for yield estimates under various levels of broomrape infestations. It was concluded that an infestation over 15% might result in a disastrous yield loss in lentil production. Therefore, some agronomic measures must be taken quickly.

Background: Ascochyta blight caused by Ascochyta fabae Speg. and broomrape (Orobanche crenata) are among the economically most significant pathogens of faba bean. Several QTLs conferring resistance against the two pathogens have been identified and validated in different genetic backgrounds. The aim of this study was to saturate the most stable QTLs for ascochyta and broomrape resistance in two Recombinant Inbred Line (RIL) populations, 29H x Vf136 and Vf6 x Vf136, to identify candidate genes conferring resistance against these two pathogens. Results: We exploited the synteny between faba bean and the model species Medicago truncatula by selecting a set of 219 genes encoding putative WRKY transcription factors and defense related proteins falling within the target QTL intervals, for genotyping and marker saturation in the two RIL populations. Seventy and 50 of the candidate genes could be mapped in 29H x Vf136 and Vf6 x Vf136, respectively. Besides the strong reduction of the QTL intervals, the mapping process allowed replacing previous dominant and pedigree-specific RAPD flanking markers with robust and transferrable SNP markers, revealing promising candidates for resistance against the two pathogens. Conclusions: Although further efforts in association mapping and expression studies will be required to corroborate the candidate genes for resistance, the fine-mapping approach proposed here increases the genetic resolution of relevant QTL regions and paves the way for an efficient deployment of useful alleles for faba bean ascochyta and broomrape resistance through marker-assisted breeding. [ABSTRACT FROM AUTHOR]

The study of allelopathic activity of plants and the isolation and characterization of the responsible allelochemicals can lead to the development of environment friendly alternative approaches to weed control. Conyza species are invasive weeds that use allelopathic activity as part of a successful strategy to outcompete neighboring plants. Broomrape weeds are parasitic plants that use host-induced germination and the formation of a haustorium as strategies to infect host plants. The control of broomrape infection in most affected crops is limited or non-existing. In the current study, we investigated the allelopathic activity of Conyza bonariensis organic extracts in suicidal germination and radicle growth of four broomrape species (Orobanche crenata, Orobanche cumana, Orobanche minor and Phelipanche ramosa). A bioactivity-driven fractionation of Conyza bonariensis extracts led to the identification of two germination-inducing molecules and two growth-inhibitory compounds. The germination-inducing metabolites had species-specific activity being hispidulin active on seeds of O. cumana and methyl 4-hydroxybenzoate active in P. ramosa. The growth-inhibitory metabolites (4Z)-lachnophyllum lactone and (4Z,8Z)-matricaria lactone strongly inhibited the radicle growth of all parasitic weed species studied. Some structure–activity relationships were found as result of the study herein presented.

Background: The parasitic plant Orobanche cumana is one of the most important threats to sunflower crops in Europe. Resistant sunflower varieties have been developed, but new O. cumana races have evolved and have overcome introgressed resistance genes, leading to the recurrent need for new resistance methods. Screening for resistance requires the phenotyping of thousands of sunflower plants to various O. cumana races. Most phenotyping experiments have been performed in fields at the later stage of the interaction, requiring time and space. A rapid phenotyping screening method under controlled conditions would need less space and would allow screening for resistance of many sunflower genotypes. Our study proposes a phenotyping tool for the sunflower/O. cumana interaction under controlled conditions through image analysis for broomrape tubercle analysis at early stages of the interaction. Results: We optimized the phenotyping of sunflower/O. cumana interactions by using rhizotrons (transparent Plexiglas boxes) in a growth chamber to control culture conditions and Orobanche inoculum. We used a Raspberry Pi computer with a picamera for acquiring images of inoculated sunflower roots 3 weeks post inoculation. We set up a macro using ImageJ free software for the automatic counting of the number of tubercles. This phenotyping tool was named RhizOSun. We evaluated five sunflower genotypes inoculated with two O. cumana races and showed that automatic counting of the number of tubercles using RhizOSun was highly correlated with manual time-consuming counting and could be efficiently used for screening sunflower genotypes at the tubercle stage. Conclusion: This method is rapid, accurate and low-cost. It allows rapid imaging of numerous rhizotrons over time, and it enables image tracking of all the data with time kinetics. This paves the way toward automatization of phenotyping in rhizotrons that could be used for other root phenotyping, such as symbiotic nodules on legumes. [ABSTRACT FROM AUTHOR]

Summary: Parasitic plants in the family Orobanchaceae, such as Striga, Orobanche and Phelipanche, often cause significant damage to agricultural crops. The Orobanchaceae family comprises more than 2000 species in about 100 genera, providing an excellent system for studying the molecular basis of parasitism and its evolution. Notably, the establishment of model Orobanchaceae parasites, such as Triphysaria versicolor and Phtheirospermum japonicum, that can infect the model host Arabidopsis, has greatly facilitated transgenic analyses of genes important for parasitism. In addition, recent genomic and transcriptomic analyses of several Orobanchaceae parasites have revealed fascinating molecular insights into the evolution of parasitism and strategies for adaptation in this family. This review highlights recent progress in understanding how Orobanchaceae parasites attack their hosts and how the hosts mount a defense against the threats. [ABSTRACT FROM AUTHOR]

The extensive diversity of the tribe Orobancheae, the most species-rich lineage of holoparasitic Orobanchaceae, is concentrated in the Caucasus and Mediterranean regions of the Old World. This extant diversity has inspired hypotheses that these regions are also centres of origin of its key lineages, however the ability to test hypotheses has been limited by a lack of sampling and phylogenetic information about the species, especially in the Caucasus region. First, we assessed the phylogenetic relationships of several poorly known, problematic, or newly described species and host-races of four genera of Orobancheae occurring in the Caucasus region-Cistanche, Phelypaea, Phelipanche and Orobanche-using nuclear ribosomal (ITS) and plastid (trnL-trnF) sequence data. Then we applied a probablistic dispersal-extinction-cladogenesis model of historical biogeography across a more inclusive clade of holoparasites, to explicitly test hypotheses of Orobancheae diversification and historical biogeography shifts. In sum, we sampled 548 sequences (including 196 newly generated) from 13 genera, 140 species, and 175 taxa across 44 countries. We find that the Western Asia (particularly the Caucasus) and the Mediterranean are the centre of origin for large clades of holoparasitic Orobancheae within the last 6 million years. In the Caucasus, the centres of diversity are composed both of long-branch taxa and shallow, recently diversified clades, while Orobancheae diversity in the Mediterranean appears to represent mainly recent diversification. [ABSTRACT FROM AUTHOR]

Broomrape weeds (Orobanche and Phelipanche spp.) are noxious parasites that infect crops using haustoria formed at the tip of their radicles. Dichloromethane extract obtained from the roots of Convolvulus arvensis strongly inhibits the radicle growth of broomrape weeds. A complex mixture of arvensic acids was isolated as the metabolites responsible of the inhibitory activity of C. arvensis extract against broomrape radicle growth via activity-guided fractionation and 1H NMR and ESI MS data. We showed that the exposure of broomrape seedlings to this arvensic acids mixture results in a strong phytotoxic effect on their radicles in four broomrape species infecting a wide range of crops worldwide. This discovery paves the way for the synthesis of new bioherbicides and could contribute to the development of efficient and sustainable management strategies for broomrape weeds, for which control in many crops is limited or non-existing.

There is current interest in the revalorization of legume crops such as one-flowered vetch (Vicia articulata) that was widely cultivated in the past, but is today underutilized. Characterization of responses of existing germplasm to major biotic constraints is crucial for cultivar development. Our studies confirm that V. articulata germplasm can be severely infected by rusts, particularly by the rusts of pea (Uromyces pisi) and lentil (U. viciae-fabae ex. L. culinaris). Only moderate levels of quantitative resistance were identified to these rusts, with no hypersensitive resistance at all. On the contrary all accessions studied were very resistant to the rusts of common vetch (U. viciae-fabae ex V. sativa), faba bean (U. viciae-fabae ex V. faba) and chickpea (U. ciceris-arietini), resistance being frequently associated with hypersensitivity. Crenate broomrape (Orobanche crenata) is known to infect Vicia species. Our field, pot and in vitro experiments showed that V. articulata can be infected by O. crenata, but levels of infection remained low compared to faba bean and pea checks. [ABSTRACT FROM AUTHOR]

In Tunisia, Orobanche foetida Poir. is considered an important agricultural biotic constraint on faba bean (Vicia faba L.) production. An innovative control method for managing this weed in faba bean is induced resistance through inoculation by rhizobia strains. In this study, we explored the biochemical dynamics in V. faba L. minor inoculated by rhizobia in response to O. foetida parasitism. A systemic induced resistant reaction was evaluated through an assay of peroxidase (POX), polyphenol oxidase (PPO) and phenyl alanine ammonialyase (PAL) activity and phenolic compound and hydrogen peroxide (H2O2) accumulation in faba bean plants infested with O. foetida and inoculated with rhizobia. Two rhizobia strains (Mat, Bj1) and a susceptible variety of cultivar Badi were used in a co-culture Petri dish experiment. We found that Mat inoculation significantly decreased O. foetida germination and the number of tubercles on the faba bean roots by 87% and 88%, respectively. Following Bj1 inoculation, significant decreases were only observed in O. foetida germination (62%). In addition, Mat and Bj1 inoculation induced a delay in tubercle formation (two weeks) and necrosis in the attached tubercles (12.50% and 4.16%, respectively) compared to the infested control. The resistance of V. faba to O. foetida following Mat strain inoculation was mainly associated with a relatively more efficient enzymatic antioxidative response. The antioxidant enzyme activity was enhanced following Mat inoculation of the infected faba bean plant. Indeed, increases of 45%, 67% and 86% were recorded in the POX, PPO and PAL activity, respectively. Improvements of 56% and 12% were also observed in the soluble phenolic and H2O2 contents. Regarding inoculation with the Bj1 strain, significant increases were only observed in soluble phenolic and H2O2 contents and PPO activity (especially at 45 days after inoculation) compared to the infested control. These results imply that inoculation with the rhizobia strains (especially Mat) induced resistance and could bio-protect V. faba against O. foetida parasitism by inducing systemic resistance, although complete protectionwas not achieved by rhizobia inoculation. The Mat strain could be used as a potential candidate for the development of an integrated method for controlling O. foetida parasitism in faba bean., Competing Interests: No authors have a competing interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Bouraoui et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

A methodology for the total and modulable synthesis of (4 Z )-lachnophyllum lactone ( 1 ), on a gram scale, is reported for the first time. The present work started with the design of a retrosynthetic pathway for the target compound, with the key step identified in Pd-Cu bimetallic cascade cross-coupling cyclization. (4 Z )-Lachnophyllum lactone ( 1 ) is an acetylenic furanone previously isolated, in a low amount, from the organic extract of the autotrophic weed Conyza bonariensis . Tested against the stem parasitic weed Cuscuta campestris in a seedling growth bioassay, (4 Z )-lachnophyllum lactone ( 1 ) showed almost 85% of inhibitory activity up to 0.3 mM in comparison with the control. At the same concentration, the compound displayed radicle growth inhibitory activity of the root parasitic weeds Orobanche minor and Phelipanche ramosa higher than 70 and 40%, respectively. Surprisingly, the compound showed a high percentage of inhibition, up to 0.1 mM, on C. bonariensis seed germination too. This versatile synthetic strategy was also used to obtain two further natural analogues, namely, (4 E )-lachnophyllum lactone ( 8 ) and (4 Z ,8 Z )-matricaria lactone ( 9 ), that showed, in most cases, the same inhibitory trend with slight differences, highlighting the importance of the stereochemistry and unsaturation of the side chain. Furthermore, all of the compounds showed antifungal activity at 1 mM reducing the mycelial growth of the olive pathogen Verticillium dahliae . The design and implementation of scalable and modulable total synthesis on a gram scale of acetylenic furanones allow the production of a large amount of these natural products, overcoming the limit imposed by isolation from natural sources. The results of the present study pave the way for the development of ecofriendly bioinspired pesticides with potential application in agrochemical practices as alternative to synthetic pesticides.

The obligate root parasitic Orobanchaceae plants Striga, Orobanche and Phelipanche spp. parasitize economically important crops, vegetables and oil plants. They are the most devastating agricultural weed pests worldwide. Based on an analysis of the climatic requirements of these parasites, very large areas of new territory are at risk of invasion if care is not taken. Recent research in combatting root parasitic weeds was reviewed based on scientific papers reported from 2010 and onwards. The countermeasures fell into eight kinds: resistant varieties, tolerant varieties, microbiological approach, cultural practices, chemical controls, host-induced gene silencing, integrated management and dissemination of technologies including the current situation survey. The development of practical, feasible and economical control technologies against root parasitic weeds would be expected by advancing and combining the countermeasures.

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. [ABSTRACT FROM AUTHOR]