Broomrape Populations Research Articles

First case of evolved herbicide resistance in the holoparasite sunflower broomrape, Orobanche cumana Wallr.

The development and commercialisation of sunflower varieties tolerant to acetolactate synthase (ALS)-inhibiting herbicides some 20 years ago provided farmers with an alternative method for the cost-effective control of Orobanche cumana. In 2020, however, two independent sunflower broomrape populations from Drama (GR-DRA) and Orestiada (GR-ORE), Greece, were reported to be heavily infested with O. cumana after application of the ALS-inhibiting herbicide imazamox. Here we have investigated the race of GR-DRA and GR-ORE and determined the basis of resistance to imazamox in the two Greek O. cumana samples. Using a set of five diagnostic sunflower varieties characterised by different resistant genes with respect to O. cumana infestation, we have clearly established that the GR-ORE and GR-DRA populations belong to the invasive broomrape races G and G+, respectively. Live underground tubercles and emerged shoots were identified at the recommended field rate of imazamox for GR-DRA and GR-ORE but not for two other standard sensitive populations in a whole plant dose response test using two different herbicide-tolerant sunflower hybrids as hosts. Sequencing of the ALS gene identified an alanine 205 to aspartate mutation in all GR-ORE samples. Most GR-DRA tubercles were characterised by a second serine 653 to asparagine ALS mutation whilst a few GR-DRA individuals contained the A205D mutation. Mutations at ALS codons 205 and 653 are known to impact on the binding and efficacy of imazamox and other imidazolinone herbicides. The knowledge generated here will be important for tracking and managing broomrape resistance to ALS-inhibiting herbicides in sunflower growing regions.

Identification and genetic diversity analysis of broomrape in Xinjiang, China

BackgroundAs a holoparasitic weed, broomrape has seriously threatened the production of economically important crops, such as melon, watermelon, processed tomato, and sunflower, in Xinjiang in recent years. However, the distribution and genetic diversity of broomrape populations in Xinjiang are not clear at present, which hinders their prevention and control. The purpose of this study was to identify the main species and the genetic differentiation structure of the broomrape population in Xinjiang.Methods and resultsIn the present study, 93 samples from different geographic regions of Xinjiang were collected to identify the species based on ITS and plastid rps2 regions, and the samples were also used to analyze the genetic diversity based on ISSR markers. The results showed that broomrape is not monophyletic in Xinjiang and consists of two major clades (Orobanche cf. aegyptiaca and O. cernua) and three subclades (O. cf. aegyptiaca var. tch, O. cf. aegyptiaca var. klz, and O. cernua.var. alt) based on phylogenetic analysis. Furthermore, the results of the genetic diversity analysis indicated that the average polymorphic information content and marker index were high values of 0.58 and 7.38, respectively, showing the efficiency of the ISSR markers in detecting polymorphism among the broomrape population studied. Additionally, the 11 selected primers produced 154 repeatable polymorphic bands, of which 150 were polymorphic. The genetic diversity of the samples was 37.19% within populations and 62.81% among the populations, indicating that the main genetic differentiation occurred among the populations. There was less gene exchange between populations, with a gene flow index (Nm) of 0.2961 (< 1). The UPGMA dendrogram indicated that most populations with similar geographical conditions and hosts were clustered first, and then all samples were separated into two major groups and seven subclusters.ConclusionThe broomrapes are mainly O. cf. aegyptiaca and O. cernua in Xinjiang, which were separated into two major groups and seven subclusters based on ISSR markers. Our results provide a theoretical basis for breeding broomrape-resistant varieties.

Analysis of genetic relationships between broomrape populations from different countries using ISSR markers

Orobanche cumana, commonly known as sunflower broomrape, poses a significant risk to sunflower cultivation in areas located along the Black Sea and across Europe. A study was conducted to analyze the genetic diversity and differentiation among populations of this parasitic plant originating from Bulgaria, Turkey, Republic of Moldova, and Romania. A total of 269 individuals from 23 populations were genotyped using 13 ISSR markers. The frequency distribution of alleles in the broomrape populations from Romania, Turkey and Bulgaria is more homogeneous than that from Moldavian populations. However, according to genetic diversity parameters O. cumana populations from Moldova and Turkey were more variable (total gene diversity Ht=0.188; 0.214), than those from Bulgaria and Romania (Ht=0.112; 0.067). The highest values of gene diversity within populations (Hs = 0.138) were found in Turkish broomrape. The value of Gst ranged between 0.359-0.516, indicating a very high level of genetic differentiation among populations. These results are consistent with low Nm values (0.468-0.895). Pairwise differentiation index (PhiPT) and Nei’s unbiased measures of genetic distance (GD) showed similar patterns, indicating a maximum (PhiPT=0.500; GD=0.261) and, respectively, minimum (PhiPT=0.238; GD=0.079) values between broomrape from Turkey and Romania, respectively, Romania and Moldova. Dendrogram constructed using the UPMGA method based on Nei's genetic distances and Pearson's dissimilarity clustered together Moldavian and Romanian broomrape and grouped in two separate clusters populations belonging to Bulgaria and Turkey. The PCA analysis confirmed the results of UPGMA clusterization. Overall, both methods suggest that the groupings of broomrape are partly determined by its geographical origin, as well as by the genetic differences and similarities accumulated over time, and are not related to virulence.

Genetic diversity of broomrape (Orobanche cumana Wallr.) populations from different geographical origins assessed by ISSR markers

Abstract The present study was focused on the assessment of genetic diversity in twenty-three populations of Orobanche cumana parasitizing on sunflower in Bulgaria, Turkey, Moldova and Romania using 13 ISSR markers. The obtained results on the genetic diversity parameters showed that the broomrape populations were characterised by a significant level of the intrapopulation diversity. In addition, descriptive population genetic statistics revealed that Turkish populations had a higher level of genetic diversity indices than populations from several areas of the northeast and east of the Balkan Peninsula included in Eastern Europe. The analysis of molecular variance showed that 38 % of the genetic variability was due to differences within populations, 34 % was due to differences among populations and the lowest molecular variation was among countries (28 %). According to clustering and PCA methods, Moldavian, Bulgarian and Romanian broomrapes shared more genetic traits with each other than with Turkish populations within a main gene pool. As a whole, all results of this study showed that there is a high intrapopulation diversity of the O. cumana gene pool in the Black Sea basin. From the clustering and PCA analyses, it can be concluded that the grouping of broomrape populations is partly determined by their geographical origin, as well as by the genetic differences and similarities accumulated over time, and is not related to virulence. The information obtained from this study may be highly relevant in contributing to the development of sustainable control strategies of the pathogen and breeding programmes for sunflower resistance to broomrape.

Genetic Structure and Diversity Analysis of Tunisian Orobanche spp. and Phelipanche spp. Using Molecular Markers

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.

A novel sunflower broomrape race with unusual virulence potentially caused by a mutation.

The sunflower broomrape (Orobanche cumana Wallr.) gene pools of the Guadalquivir Valley and Cuenca province in Spain had predominantly race-F virulence. A new race G was observed recently in the Guadalquivir Valley potentially due to the genetic recombination of the avirulence genes of both gene pools. In this research, we have studied populations with atypical virulence from Cuenca. These populations parasitize on DEB2 sunflower line, resistant to all race-G populations evaluated. Ten populations collected in Cuenca province were evaluated with sunflower differential lines and genotyped with 67 SNP markers. Although genetic recombination with individuals of the Guadalquivir Valley gene pool has been observed in most populations, recombination of avirulence genes was discarded as the cause of the new virulence because the population with the highest degree of attack on DEB2 showed no introgression from an external gene pool. Accordingly, a point mutation is proposed as the putative cause of the new virulence. The present study provided a detailed characterization of each population, including the accurate classification of the individuals belonging to each of the classical Spanish gene pools, F1 hybrids, and those that evolved from hybridization between both gene pools. This information is essential to understand how sunflower broomrape populations are evolving in Spain, which in turn may be helpful to understand the dynamics of sunflower broomrape populations in other areas of the world and use this information to develop durable strategies for resistance breeding.

Virulence, genetic diversity, and putative geographical origin of sunflower broomrape populations in Morocco

Sunflower broomrape (Orobanche cumana Wallr.) was detected for the first time parasitizing sunflower in Morocco in 2016. Seeds of three broomrape populations from two separate areas of Morocco, Souk Al Arbaa (populations SA1 and SA2) and Meknès (Population MK1) were collected. The populations’ virulence, genetic diversity, and putative area of origin were examined. Race classification using a set of sunflower differential lines showed that MK1 was a race-E population, while SA1 and SA2 were race-G populations. The analysis with 192 SNP markers showed that SA1 and SA2 populations are genetically similar and very distant from the MK1 population. The three populations exhibited low intrapopulation diversity. Comparisons with populations from other areas showed that MK1 was introduced from a race-E population from the Guadalquivir Valley gene pool in Southern Spain, probably before 1988. Populations SA1 and SA2 showed close relationships with a population from Russia, although more exact knowledge of the origin of these populations requires further investigation. Since the SA and MK populations were collected from areas located approx. 100 km apart, the risks of mixing and recombining both gene pools to produce more virulent variants must be considered.

Peculiarities of the sunflower breeding for resistance to broomrape (orobanche cumana wallr.)

Purpose and Objectives. Our purpose was to find available information on the sunflower breeding for resistance to the broomrape. To achieve this purpose, we solved following tasks: to review publications covering the history and current state of research into the subject; find out the specifics of such studies; and to highlight the main unresolved issues for the organization of further work.&#x0D; Materials and Methods. Publications of Ukrainian and foreign scientists became the material for the study: articles in journals and conference abstracts.&#x0D; Results and Discussion. In the article, publications covering domestic and foreign studies of the peculiarities of sunflower breeding for resistance to the parasitic plant Orobanche cumana Wallr. are collected and reviewed. The changes in the race composition of the parasite since the beginning of the 19th century, which have accelerated in recent years, are described. Experiments and breeding for resistance to the broomrape began in 1909-1913, when there was only one (the first) broomrape race A. Currently, the existence of the seventh race (G) and the broomrape biotypes affecting race G-resistant sunflower accessions has been recognized in the world. During the last 20 years, the appearance of new broomrape races was observed in the countries where sunflowers are grown with violations of crop rotation requirements.&#x0D; Marking resistance genes of domestic plants and determining the molecular polymorphism of both host and parasitic plants are important problems of genetics, solving of which is aimed at the improvement of sunflowers in terms of resistance to the broomrape. The identification of genes of resistance to the broomrape and the development of methods for their marking are discussed. Studies in the genetics of resistance to O. cumana are limited by few relevant molecular markers. Scientists announced that they had onstructed a molecular genetic map of linkage groups with the Or7 gene of resistance to race G. Genetic studies of the broomrape as a plant are mainly focused on the structure and genetic diversity of parasite populations. The broomrape aggressiveness depends on weather and climate, so an increase in temperatures and lack of precipitation can lead to the broomrape spread over large areas. Scientists adapt the phytotron test for resistance to the broomrape to modern equipment, developing certain methodological subtleties. In addition, new methods of evaluation are developed: histological and molecular genetic assessments&#x0D; Conclusions. The sunflower broomrape is one of the main biotic factors that harm the crop fields. The peculiarity of the breeding for resistance is associated with continuous formation of new races of the parasite. Studies by scientists from different countries on the formation of new physiological races of the broomrape indicate the annually growing threat from the parasite, the need for constant monitoring of broomrape populations and the continuous development of research in this direction. Several genes of resistance to the broomrape have been identified; methods of their marking have been developed; this ensures success in improving the existing and developing new progressive approaches in the sunflower breeding for resistance to the parasite. The specificity of control of resistance to the broomrape, which is determined by genetic factors, was established. Thus, genetic methods are the best ones to fight against the broomrape. However, inheritance patterns of resistance to new, virulent, widespread in Ukraine broomrape races are not described in the literature, though it is important for the creation of commercial hybrids. The relationships between resistance to new virulent broomrape races, which are common in Ukraine, and valuable economic characteristics in F1 hybrids should be also studied. Taking into account the recent climatic changes, in particular a rise in air temperatures and consequences of this global process, one can predict an increase in the intensity of damage to sunflowers by the parasite, which prompts breeders of the crop to combine resistance to adverse abiotic factors and resistance to the broomrape

Assessment of the Genetic Structure and Diversity of Orobanche cumana populations from Turkey Using Simple Sequence Repeat Markers

Orobanche cumana Wallr. known as sunflower broomrape is a holoparasitic plant that causes huge yield losses in sunflower (Helianthus annuus L.) fields. Genetic characterization, genetic diversity, and race determination studies in O. cumana are very significant for preventing threats in sunflower fields. In this study, the broomrape populations sampled from Edirne, Kırklareli, Tekirdağ, and Adana provinces were used for genetic characterization. The sensitive Özdemirbey sunflower variety was used for growing O. cumana individuals. Eight simple sequence repeat (SSR) loci (Ocum52, Ocum70, Ocum81, Ocum87, Ocum108, Ocum141, Ocum160, and Ocum196) were used for the evaluation of genetic characterization and diversity of broomrape populations. All studied SSR loci were found to be polymorphic and yielded a total of 22 alleles in 143 samples analyzed. Na = 2.089 (mean number of alleles per locus), Ne = 1.390 (mean effective alleles), I = 0.392 (mean Shannon’s information index), Ho = 0.156 (mean observed heterozygosity), He = 0.239 (mean expected heterozygosity), and PIC = 0.228 (mean polymorphic information content) were calculated to assess genetic diversity of O. cumana populations.. As a result of molecular variance analysis, it was concluded that found that the genetic diversity of the populations was 38% among the population. The remaining 23% and 39% were due to among individuals and within individuals, respectively. The UPGMA method and STRUCTURE analysis divided the studied populations into 2 groups. Cluster I included LK2013, HT2016, T2018, and LE2013 populations, while group 2 included AE2003, AD2018, and MT2013 populations. The results we obtained have enabled us to reach important genetic diversity information about O. cumana, and the information obtained will provide important contributions for planned studies in the future.

Genetic variation within and among some broomrape populations of different geographical origin

Knowledge of the genetic variation and their evolutionary basis in Orobanche cumana Wallr. populations are essential for establishment of the risks of new physiological races emergence of this devastating sunflower parasite. In the current study, the genetic diversity of 33 broomrape populations from 6 countries (Republic of Moldova, Romania, Bulgaria, Serbia, Turkey and China) was analyzed, using two molecular marker systems (SSR and ISSR). Analysis of molecular variance (AMOVA) at different hierarchical levels (within populations, between populations and between groups of populations - countries, races) revealed a high genetic variation among populations, when no population structure was considered (i), an approximately equal partitioning of total variance among countries, populations and within populations (ii) and a low genetic variance attributed to divergence between races (iii).

Wild Helianthus species: A reservoir of resistance genes for sustainable pyramidal resistance to broomrape in sunflower.

Orobanche cumana Wall., sunflower broomrape, is one of the major pests for the sunflower crop. Breeding for resistant varieties in sunflower has been the most efficient method to control this parasitic weed. However, more virulent broomrape populations continuously emerge by overcoming genetic resistance. It is thus essential to identify new broomrape resistances acting at various stages of the interaction and combine them to improve resistance durability. In this study, 71 wild sunflowers and wild relatives accessions from 16 Helianthus species were screened in pots for their resistance to broomrape at the late emergence stage. From this initial screen, 18 accessions from 9 species showing resistance, were phenotyped at early stages of the interaction: the induction of broomrape seed germination by sunflower root exudates, the attachment to the host root and the development of tubercles in rhizotron assays. We showed that wild Helianthus accessions are an important source of resistance to the most virulent broomrape races, affecting various stages of the interaction: the inability to induce broomrape seed germination, the development of incompatible attachments or necrotic tubercles, and the arrest of emerged structure growth. Cytological studies of incompatible attachments showed that several cellular mechanisms were shared among resistant Helianthus species.

Racial status of Orobanche cumana Wallr. in some countries other the world

Abstract The study represents a review of the evolution of the parasitic plant Orobanche cumana Wallr. and current racial status in some sunflower cultivating countries. Identification of racial status of broomrape populations belonging to eight sunflower cultivating countries from Europe and Asia (Republic of Moldova, Romania, Bulgaria, Ukraine, Spain, Turkey, Serbia and China) revealed the presence of high virulent races G and H in the majority of countries, except Serbia, where accessions belonging to race E or less virulent than E were found. The most virulent race H was identified particularly in the Black Sea area (Romania, Ukraine and Turkey). Additionally, the emergence of new biotypes characterized by high virulence, overcoming the resistance genes to race H was observed in some areas of the Republic of Moldova, Romania and Turkey, which signifies the importance of periodic evaluations of racial status for the prevention of occurrence and dissemination of new races. Analyzing the occurrence chronology of broomrape races in different countries we conclude that by the mid-1990s, the state of play was relatively stable, the most aggressive race being E. After this period the process of O. cumana development and appearance of new more aggressive and virulent biotypes became faster, which may be explained by the intensification of sunflower breeding activities and, respectively by the selection pressure exerted on the parasite by new resistant hybrids.

Variability of some broomrape populations from China. Genotyping and determination of genetic polymorphism (II)

Genetic diversity within a population is reflected by variations in genetic material among individuals and can manifest at the phenotypic level through new characters or traits. The emergence of a large number of O. cumana races in a short period of time demonstrates that there are higher genetic variability in populations and a high ability to adapt in the face of environmental conditions. The aim of the research presented in this article was to study the intraand interpopulation genetic diversity and genetic relationships between individuals of three populations of O. cumana from different geographical regions of the People’s Republic of China based on molecular markers (ISSR and SSR). The high intrapopulation genetic variability calculated on the basis of the allelic diversity parameters and specific genetic diversity coefficients was revealed by SSR markers while as for the ISSR primers a high degree of genetic variations was found at the interpopulation level. UPGMA clustering and principal component analysis performed according to both sets of molecular markers allowed to devide all genotypes into 5 major groups for the degree of dissimilarity and level of aggression. This study is of interest in understanding the population genetic structure of the parasitic species of O. cumana from China and could contribute to the development of pathogen control durable strategies and effective sunflower breeding programs to broomrape resistance.

Dynamics of change in broomrape populations (Orobanche cumana Wallr.) in Romania and Russia (Black Sea area)

Abstract The emergence of new broomrape populations (races) has been observed in the past 20 years in several countries (Romania, Moldova, Ukraine, Russia, Turkey, Bulgaria, Spain, Serbia, and China) where sunflower is frequently grown in the same sites without applying traditional crop rotations. Differential lines for sunflower broomrape races A to F have been secured. The new broomrape races have been identified by researchers as races G and H. The question of whether the same broomrape mutations can occur in one year and affect the same countries remains unsolved. Several results of new broоmrape population emergences in some of the affected will be presented in the paper. A total of 390 genotypes were studied at four Romanian localities (Cuza Voda, Crucea-Stupina, Braila-Valea Canepii, and Tulcea-Agighiol) in 2014. At all four localities, a certain degree of sunflower broomrape infestation was observed in control hybrids and lines (Performer, LC-1093, LG-5661, and PR64LE20), which indicated the emergence of new populations higher than race H. The 390 studied genotypes had different reactions in all four localities. In 2015, 10 hybrids and controls were studied at five Romanian localities (Ciresu-Braila, Iazu-Ialomita, Stupina-Constanta, Topolog-Tulcea, and Viziru-Braila) and, according to the results, only hybrid Hy-7 was resistant in all localities. The results obtained from the three studied localities showed the emergence of new sunflower broomrape populations not controlled by gene for race H. Self-fertilization of hybrid Hy-7 produced the F2 generation in 2016. In 2017, broomrape resistance was studied at the infested (contaminated) plot at the All-Russian Research Institute of Oil Crops by the name of Pustovoit V.S. – VNIIMK in Rostov on Don. The plot was found to be infested by new broomrape populations originating from Russia, Ukraine, Romania, Turkey, and Spain. The obtained results showed an infestation degree in 17.1% plants of hybrid Hy-7, 35% in the F2 generation of Hy-7, control hybrids PR64LE25, LG-5580 and Donskoy-22 showed 19.4, 23, and 100% broomrape infestation, respectively. In conclusion, the plot contained broomrape populations which cannot be controlled by race H gene. According to the obtained results, a permanent change in variability of broomrape populations can be confirmed practically year after year. At present, new broomrape populations found at several localities are locally dispersed. Geneticists and breeders have to make joint efforts in further detailed studies of broomrape variability.

Characterization of post‐haustorial resistance to sunflower broomrape

AbstractThe development of durable resistance to broomrape (Orobanche cumana Wallr.) in sunflower (Helianthus annuus L.) requires detailed characterization of the genetic and physiological bases of resistance. The objective of the present study was to map the resistance gene accurately, and to characterize the mechanism of resistance to broomrape observed in a sunflower inbred line (PHSC1102). PHSC1102, which was consistently resistant against race F and race G populations of broomrape, was crossed with PHSC1201, which was susceptible to races F and G. A mapping population of 150 F2 genotypes was phenotyped by evaluating F2:3 families for resistance to broomrape races FGV and GTK. The use of single nucleotide polymorphism (SNP) markers mapped the OrSII gene to Linkage Group 4 (LG4) of the sunflower genome. Mini‐rhizotron and histological studies of the resistant line revealed that the attachment of broomrape to host roots was similar in both the resistant and susceptible lines and that the resistance was observed at a late stage (i.e., after tubercle development). Interestingly, the resistance of the PHSC1102 line was associated with the production of phenolic compounds, which were hypothesized to restrict the parasite's growth. This research provides novel and valuable information about the host–parasite interactions between sunflower and broomrape.

Genetic Diversity Analysis of Sunflower Broomrape Populations from Republic of Moldova Using ISSR Markers

The holoparasitic Orobanche cumana Wallr. has become a limiting factor for sunflower yield in Eastern Europe. Better knowledge of broomrape biology, including genetic diversity, is important in any attempt to develop resistance-breeding programs. There is little information available on the diversity of broomrape in the Republic of Moldova. The aim of this study was to evaluate the interpopulation variability of the Orobanche cumana Wallr. using Inter Simple Sequence Repeats (ISSR) markers. Data from the present study revealed that ISSR marker system could be used for estimating genetic diversity, since it had high percent polymorphism. All of the genetic parameters indicated that the populations from Center are genetically different from those collected in the South and North regions of the Republic of Moldova. The results of genetic polymorphism showed that the application of 14 ISSR markers made it possible to group the studied 39 broomrape populations into different clusters. The association with geographic origin was established.

First Report of Phytomyza orobanchia (Diptera: Agromyzidae) from Poland and Chymomyza amoena (Diptera: Drosophilidae) on Phelipanche ramosa (Orobanchaceae)

Field surveys conducted in Poland in Sep and Oct 2017 revealed infestations of the parasitic plant Phelipanche ramosa (L.) Pomel (Orobanchaceae), also known as branched broomrape, by larvae of the monophagous fly Phytomyza orobanchia Kalt. (Diptera: Agromyzidae). A single broomrape plant could be infested by 1 to 10 larvae of P. orobanchia, and 70 to 80% of the broomrape population was infested. This fly is one of the most effective biological control agents of broomrape. Also, a single female of an alien species of drosophilid, Chymomyza amoena (Loew) (Diptera: Drosophilidae), was observed in 1 locality in Sandomierz County, near Szewce, Poland.

First Report ofSmynthurodes betae(Hemiptera: Aphididae) onPhelipanche ramosa(Orobanchaceae)

The bean root aphid, Smynthurodes betae Westwood (Aphididae: Eriosomatinae: Fordini) is reported for the first time feeding on haustoria of branched broomrape, Phelipanche ramosa, (Orobanchaceae) a cropparasitic plant. Field surveys conducted in Poland revealed infestations of P. ramosa by nymphs and adult apterous females of a secondary-host generation of S. betae in 1 locality in Sandomierz County, near Szewce, Poland. Numerous nymphs of S. betae fed on broomrape sap, resulting in poor growth or dead shoots, and 10 to 20% of the total population of broomrape was infested. Potential use of this insect as a biological control method for invasive broomrapes requires further study.

Genetic diversity and race composition of sunflower broomrape populations from Tunisia

Sunflower broomrape ( Orobanche cumana Wallr.) was detected in 2010 for the first time in sunflower fields of Tunisia, in the Beja region. No information is available on the race composition and genetic diversity of the broomrape populations parasitizing sunflower in that area. Plant tissue and seeds were collected from nine populations in Beja Sud (ORD, ORE), Amdoun (ORF, ORG), and Beja Nord (ORH to ORL) areas of the Beja region. Virulence studies on populations ORD, ORH and ORK revealed that the ORD population was essentially race E, whereas race G individuals were present in ORH and ORK poulations, with greater frequency in the ORK population. Cluster analysis of inter-population relatedness indicated that Tunisian populations were more related to Eastern European than to Spanish populations, with the Beja Nord populations clustering separately from the rest of Tunisian populations. Analysis at the intra-population level of the ORD, ORG, ORH and ORK populations revealed the existence of two gene pools (GP1 and GP2), that were present in all populations at different frequencies. GP2 was at a lower frequency (1/14) in ORD and ORG but at higher frequencies in ORH (5/15) and ORK (8/14). This indicates that GP1 was probably an initial introduction of a race E population, while GP2 is most likely a later introduction of a race G population, introduced initially in Beja Nord area but now spreading to other areas in the region. The risk of a generalized expansion of race G of broomrape in this sunflower cultivation area is discussed.

First Report of Sunflower Broomrape, Orobanche cumana Wallr., in Morocco

Sunflower broomrape (Orobanche cumana Wallr.) is a chlorophyll-lacking and holoparasitic plant that parasitizes a limited range of hosts. In the wild, it parasitizes on a few species of the Asteraceae, whereas in agricultural fields, it is exclusively found growing on sunflower (Fernandez-Martinez et al. 2015). Sunflower broomrape is a serious threat for sunflower production in Europe and Asia (Shi et al. 2015). In northern Africa, this parasitic weed was first identified in Tunisia in 2010 (Amri et al. 2012). It was not until 2016 that sunflower broomrape was observed for the first time in Morocco, when some sunflower fields were heavily infested with this parasite in the area of Souk Al Arbaa (34°41′N, 5°59′W, 37 m above sea level), in the province of Kenitra. The degree of virulence varied from 0 to 20 shoots per sunflower plant, and seed yield losses reached more than 80%, according to farmers’ statements and our own estimations. Sunflower broomrape populations are classified into physiological races, named A through H in the literature. Races F, G, and H are the most commonly reported in several countries (Martin-Sanz et al. 2016). However, no differential lines are currently available to differentiate between races G and H. Therefore, a nomenclature has been proposed to name populations overcoming race F resistance as race G with an indication of the region of collection (Martin-Sanz et al. 2016). To identify the race of sunflower broomrape population collected in Souk Al Arbaa, eight differential sunflower lines were used, from line B117, having no resistant genes, to line DEB2, resistant to all race G populations evaluated thus far. Evaluation of the virulence of the broomrape population against these lines was conducted under growth chamber conditions at 25/20°C (day/night) with a 16-h photoperiod and photon flux density of 300 µmol/m²·s. Twenty plants of each differential line were evaluated in multipot tray with a pot volume of 40 cm³. Pots were filled with a soil mixture of sand and peat (1:1 by volume) inoculated with broomrape seeds at a concentration of 0.28 mg per gram of soil. Sunflower seeds were germinated in moistened filter paper and then planted in the pots. Evaluation of parasitization symptoms was done after 8 weeks by uprooting the plants and counting the number of nodules in the roots of each sunflower plant. All differential lines resistant to races B to F were parasitized by the sunflower broomrape population, and only line DEB2 was completely resistant, which indicated that the Moroccan population should be classified as a race G. Because the evaluation included line P96, which is resistant to the race G populations of the Guadalquivir Valley in Southern Spain (Martin-Sanz et al. 2016), which is the closest infested area, it can be discarded that the Moroccan broomrape population originated from that area. Following the recently proposed nomenclature, the name of the Souk Al Arbaa (Province of Kenitra) population is proposed as race GKE. This is the first report of O. cumana on sunflower in Morocco. Urgent measures must be taken to manage this population of broomrape and protect sunflower cultivation in Morocco.