Molecular Studies on Sunflower Broomrape (Orobanche cumana Wallr.)

Los jopos (Orobanche spp. y Phelipanche spp.) son un grupo de aproximadamente 170 especies de plantas holoparásitas distribuidas principalmente en el Hemisferio Norte. A pesar de que la mayor parte de Orobanche spp. sólo parasitan plantas silvestres, algunas de ellas se han convertido en malas hierbas nocivas en un rango variable de cultivos. Orobanche cumana Wallr. se distribuye de forma natural desde Asia Central hasta el sudeste de Europa, dónde parasita especies silvestres de la familia Asteraceae. La costa del Mar Negro en el este de Bulgaria es una de las principales áreas naturales de distribución de O. cumana, dónde esta especie se encuentra principalmente parasitando Artemisia maritima L. Esta especie, conocida como jopo del girasol (Helianthus annuus L.), es también una importante mala hierba parásita de este cultivo, dónde fue observada por primera vez parasitando girasol en Rusia en la década de 1890. Orobanche cumana está presente en los cultivos de girasol en muchos países de todo el mundo, especialmente en el centro y este de Europa, España, Turquía, Israel, Rusia, Ucrania, Irán, Kazajstán, China, Francia y Túnez. En la mayoría de estas áreas, O. cumana causa severas pérdidas de rendimiento en los cultivos de girasol. Orobanche cumana se encuentra en España como una especie alóctona que parasita al girasol cultivado exclusivamente, a diferencia de la especie estrechamente relacionada O. cernua L., que es una especie autóctona que sólo parasita huéspedes silvestres de la familia Asteraceae, principalmente Artemisia spp. Durante muchos años, O. cumana se distribuyó en el Valle del Guadalquivir (Andalucía, Sur de España) y en la provincia de Cuenca (Catilla-La Mancha, Centro de España), pero en los últimos años, se ha extendido a otras áreas de cultivo de ambas zonas y en nuevos campos de otras regiones como Castilla y León (Norte de España). La información sobre la diversidad genética, la dinámica de poblaciones, el sistema de reproducción, el flujo genético y la genética de la virulencia en O. cumana es escasa, especialmente en relación con el análisis molecular entre y dentro de las poblaciones, debido a la falta de marcadores moleculares adecuados para este tipo de estudios. Sólo unos pocos estudios moleculares se han llevado a cabo en O. cumana, limitados a la evaluación de la diversidad genética a través de isoenzimas o marcadores RAPD. Además, sólo algunos estudios se han descrito sobre las interacciones genéticas entre formas silvestres y de malas hierbas de especies de plantas parásitas. La aplicación de estos estudios es importante para el desarrollo de estrategias de mejora para el control a largo plazo que implica la resistencia genética en girasol. Por otra parte, el conocimiento de las interacciones entre los genotipos silvestres y de malas hierbas de las plantas parásitas es importante porque la vegetación silvestre puede jugar un papel como reservorio de diversidad genética para la superación de los mecanismos de resistencia genética en los cultivos huéspedes. Pero, por otro lado, la evolución de la virulencia en las poblaciones de malas hierbas parásitas también puede tener un impacto sobre la distribución de las especies en la naturaleza. Unido a esto, se necesitan marcadores alternativos como marcadores microsatélites (SSRs) que son reproducibles, no influenciados por el ambiente, multialélicos y codominantes, para permitir análisis más efectivos en O. cumana. Dado que los estudios sobre la variabilidad genética de poblaciones de O. cumana se han basado en un número restringido de poblaciones recolectadas en girasol y tipos de marcadores, una evaluación a mayor escala podría contribuir a una mejor comprensión de la estructura genética y dinámica de la especie. Tampoco hay información sobre la estructura genética de poblaciones de O. cumana que parasitan especies silvestres y su relación con las poblaciones de malas hierbas parásitas en zonas en las que conviven, y su virulencia en girasol. Como los recursos disponibles para estudios moleculares con...Broomrapes (Orobanche spp. and Phelipanche spp.) are a group of around 170 holoparasitic plant species mainly distributed in the Northern Hemisphere. Even though most of the Orobanche spp. only parasitize wild plants, some of them have become noxious weeds on a variable range of cultivated hosts. Orobanche cumana Wallr. is naturally distributed from Central Asia to Southeastern Europe, where it parasitizes wild Asteraceae species. The Black Sea coast in Eastern Bulgaria is one of the main natural distribution areas for O. cumana, where this species is mainly found parasitizing Artemisia maritima L. This species, known as sunflower broomrape, is also an important parasitic weed of sunflower (Helianthus annuus L.), where it was first observed parasitizing this crop in Russia in the 1890s. Orobanche cumana is present in sunflower crops in many countries around the world, especially in Central and Eastern Europe, Spain, Turkey, Israel, Russia, Ukraine, Iran, Kazakhstan, China, France and Tunisia. In most of these areas, O. cumana causes severe yield losses in sunflower crops. Orobanche cumana is found in Spain as an allochthonous species parasitizing exclusively cultivated sunflower, in contrast to the closely related species O. cernua L., which is an autochthonous species that only parasitizes wild Asteraceae hosts, mainly Artemisia spp. For many years, O. cumana was distributed in the Guadalquivir Valley (Andalucía, Southern Spain) and Cuenca province (Castilla-La Mancha, Central Spain), but in recent years, it has spread to other areas of these both cultivation regions and new fields in other regions such as Castilla y León (Northern Spain). Information on genetic diversity, population dynamics, mating system, gene flow and virulence genetics in O. cumana is scarce, particularly concerning molecular analysis among and within populations, due to the lack of suitable molecular markers for such studies. Only a few molecular studies have been conducted in O. cumana, restricted to evaluating genetic diversity through isoenzymes or RAPD markers. Furthermore, only some studies have been described on genetic interactions between wild and weedy forms of parasitic plant species. The application of these studies is important for the development of long-term breeding strategies for control involving genetic resistance in sunflower. Moreover, knowledge about interactions between wild and weedy genotypes of parasites is significant because wild vegetation may play a role as reservoir of genetic diversity for overcoming genetic resistance mechanisms in the host crops. But on the other hand, evolution of virulence in weedy populations may also have an impact on the distribution of the species in the wild. Coupled with this, alternative markers such as Simple Sequence Repeat (SSR) markers, which are reproducible, neutrally evolving, multiallelic and co-dominant, are needed to enable more powerful analyses in O. cumana. Since studies on genetic variability of O. cumana populations have been based on restricted numbers of weedy populations collected on sunflower and marker types, a larger-scale evaluation would contribute to a better understanding of genetic structure and dynamics of this species. There is also no information on the population structure of O. cumana populations parasitizing wild species and their genetic relationship with weedy populations in areas where they co-exist, and their virulence on sunflower. As very limited SSR resources are available for molecular research in O. cumana and other Orobanche spp., we developed and characterized a collection of SSR primer pairs for sunflower broomrape. Four thousand two hundred SSR-containing candidate sequences were obtained from O. cumana using Next Generation Sequencing (454 GS-FLX Titanium), from which 298 SSR primer pairs were designed and 217 of them used for validation. Seventy nine SSR primers produced reproducible, high quality amplicons of the expected size that were polymorphic among 18 O

Phylogenetic relationships and genetic diversity among Orobanche cumana Wallr. and O. cernua L. (Orobanchaceae) populations in the Iberian Peninsula

Orobanche cumana is found in the Iberian Peninsula as an allochthonous species parasitizing exclusively sunflower, in contrast to the closely related species Orobanche cernua, which is an autochthonous species that only parasitizes wild Asteraceae hosts. Ten O. cumana populations were collected in the two traditional areas of sunflower broomrape occurrence, the Guadalquivir Valley, Southern Spain (six populations) and Cuenca province, Central Spain (four populations). Twelve O. cernua populations were collected on wild hosts across its natural distribution area in Southeastern Spain. Genetic relationships within and between both sets of populations were studied using a set of 50 robust and co-dominant SSR markers from O. cumana. The results supported the taxonomic separation of the two species and the existence of two distant genetic groups for O. cumana, one in Guadalquivir Valley and another one in Cuenca province. The inter- and intra-population variability was extremely low for O. cumana, whereas the overall genetic diversity was much higher for O. cernua. The genetic structure of O. cumana populations probably reflects a founder effect, with the two genetically distant groups deriving from separate introduction events. The high degree of genetic differentiation observed in O. cernua is mainly explained on the basis of restricted gene flow due to ecological barriers together with the occurrence of a predominantly self-pollinating mating system. Complementary diversity studies on both species in its current distribution area are required for understanding global genetic variability and evolutionary characteristics of the parasitism.The study was partially funded by Fundación Ramón Areces, Madrid, Spain. R. Pineda-Martos was the recipient of a Ph.D. fellowship from the Spanish National Research Council (CSIC) (JAEPre_08_00370).Peer Reviewe

Genetic studies in sunflower broomrape

Much research has been conducted to identify sources of genetic resistance to sunflower broomrape (Orobanche cumana Wallr.) and to study their mode of inheritance. However, studies on the parasite have been scarce. This manuscript reviews three genetic studies in sunflower broomrape. First, the inheritance of the absence of pigmentation in a natural mutant of this species with yellow plant color phenotype was studied. In a first stage, lines from the unpigmented mutant and a normally pigmented population were developed by several generations of self-pollination. Plants of both lines were crossed and the F1, F2, and F3 generations were evaluated. The results indicated that plant pigmentation is controlled by a partially dominant allele at a single locus. Second, the unpigmented mutant was used to evaluate outcrossing potential of the species. Two experiments in which single unpigmented plants were surrounded by normally pigmented plants were conducted under pot and field conditions. The cross-fertilization rate was estimated as the percentage of F1 hybrids in the progenies of unpigmented plants, which averaged 21.5% in the pot and 28.8% in the field experiment. The results indicated that, under the conditions of this study, the species was not strictly self-pollinated. Finally, the inheritance of avirulence was studied in crosses of plants from lines of O. cumana races E and F, developed by several generations of self-pollination. The F1 and F3 generations were evaluated on the differential line P-1380 carrying the race-E resistance gene Or5. The results suggested that race E avirulence and race F virulence on P-1380 are allelic and controlled by a single locus, which confirmed the gene-for-gene theory for the O. cumana-sunflower interaction.The manuscript reviews research partially funded by Fundación Ramón Areces, Madrid. The contribution of Dr. Enrique Quesada Moraga, entomologist from the University of Córdoba, Spain, to taxonomic classification of pollinators is gratefully acknowledged. R. Pineda-Martos was the recipient of a PhD fellowship from the Spanish National Research Council (CSIC) (JAEPre_08_00370)Peer Reviewe

Challenges, gaps, and opportunities

UID/AGR/04129/LEAF UIDB/04647/2020 UIDP/04647/2020Urban agriculture (UA) plays a key role in the circular metabolism of cities, as it can use water resources, nutrients, and other materials recovered from streams that currently leave the city as solid waste or as wastewater to produce new food and biomass. The ecosystem services of urban green spaces and infrastructures and the productivity of specific urban agricultural technologies have been discussed in literature. However, the understanding of input and output (I/O) streams of different nature-based solutions (NBS) is not yet sufficient to identify the challenges and opportunities they offer for strengthening circularity in UA. We propose a series of agriculture NBS, which, implemented in cities, would address circularity challenges in different urban spaces. To identify the challenges, gaps, and opportunities related to the enhancement of resources management of agriculture NBS, we evaluated NBS units, interventions, and supporting units, and analyzed I/O streams as links of urban circularity. A broader understanding of the food-related urban streams is important to recover resources and adapt the distribution system accordingly. As a result, we pinpointed the gaps that hinder the development of UA as a potential opportunity within the framework of the Circular City.publishersversionpublishe

Towards a Cross-Sectoral View of Nature-Based Solutions for Enabling Circular Cities

A framework developed by the COST Action Circular City (an EU-funded network of 500+ scientists from 40+ countries; COST = Cooperation in Science and Technology) for addressing Urban Circularity Challenges (UCCs) with nature-based solutions (NBSs) was analyzed by various urban sectors which refer to different fields of activities for circular management of resources in cities (i.e., reducing use of resources and production of waste). The urban sectors comprise the built environment, urban water management, resource recovery, and urban farming. We present main findings from sector analyses, discuss different sector perspectives, and show ways to overcome these differences. The results reveal the potential of NBSs to address multiple sectors, as well as multiple UCCs. While water has been identified as a key element when using NBSs in the urban environment, most NBSs are interconnected and also present secondary benefits for other resources. Using representative examples, we discuss how a holistic and systemic approach could facilitate the circular use of resources in cities. Currently, there is often a disciplinary focus on one resource when applying NBSs. The full potential of NBSs to address multifunctionality is, thus, usually not fully accounted for. On the basis of our results, we conclude that experts from various disciplines can engage in a cross-sectoral exchange and identify the full potential of NBSs to recover resources in circular cities and provide secondary benefits to improve the livelihood for locals. This is an important first step toward the full multifunctionality potential enabling of NBSs

Caracterización de una colección de Orobanche cumana (jopo de girasol) recogida en la península Ibérica durante 20 años

Resúmenes del XIII Congreso de la Sociedad Española de FitopatologíaPeer reviewe

Identification, characterisation and discriminatory power of microsatellite markers in the parasitic weed Orobanche cumana

Summary: Orobanche cumana is an obligate root parasite of sunflower. It represents a major agricultural problem in many countries of southern and eastern Europe. Information on O. cumana population genetics, structure and dynamics is scarce, particularly due to the lack of suitable molecular markers for such studies. The objective of this study was to identify and characterise simple sequence repeat (SSR) markers for O. cumana. Four thousand two hundred SSR-containing candidate sequences were obtained from O. cumana using next-generation sequencing, from which 298 SSR primer pairs were designed and 217 of them used for validation. Seventy nine SSR primers produced reproducible, high quality amplicons of the expected size that were polymorphic among 18 O. cumana populations from different geographical locations and hosts (sunflower, wild hosts from the Compositae family). The number of alleles per locus ranged from 2 to 10, with an average polymorphism information content value of 0.37. The O. cumana SSR markers were highly transferable to the closely related species Orobanche cernua. SSR markers showed high resolving power; UPGMA cluster analysis allowed proper classification of Orobanche spp. samples into species (O. cumana and O. cernua), geographical origin and host. The functional SSR markers reported in this study constitute a valuable tool for genetic analyses in O. cumana and related species and will contribute insights into the biology and genetics of this parasitic weed. © 2013 European Weed Research Society.The study was partially funded by Fundación Ramón Areces, Madrid. R. Pineda-Martos was the recipient of a PhD fellowship from the Spanish National Research Council (CSIC) (JAEPre_08_00370).Peer Reviewe

Genetic diversity of Orobanche cumana and Orobanche cernua populations as revealed by variability of Internal Transcribed Spacers1/2 of ribosomal cistron and ribulose-bisphosphate carboxylase pseugene

Kirilova, Ina et al.-- Trabajo presentado en el Third Internacional Symposium on broomrape (Orobanche spp.) in Sunflower, celebrado en Córdoba (España) del 3 al 6 de junio de 2014.The sunflower broomrape - Orobanche cumana (Wallr) parasitizes on roots of sunflower plants and is a serious constraint on sunflower production, causing yield losses of up to 60%. The variability of Internal Transcribed Spacers1/2 of ribosomal cistron (ITS1/2) and ribulose-bisphosphate carboxylase pseugene (RbcL) in 32 samples of O. cumana and 4 samples O. crenata collected from different European locations were studied. The results showed that O. cumana can be differentiated from O. cernua, by single C/T transition located in ITS2 (rel. position 423). Rubisco large subunit in O cumana differs from O. cernua with two transversion: T/G (rel. position 15) and A/C (rel. position 84). The genetic diversity observed in O. cumana was lower than in O. cernua. When comparing the ITS and rbcL sequences isolated from O. cernua two single SNPs were found that can discriminate different origins. Both ITS1/2 and rbcL sequences isolated from O. cumana however were completely homogeneous, despite the fact that samples were collected form very distant locations: from Volgograd, Russia to the East to Spain to the West. This observation is in favor of hypothesis that the move of O. cumana from wild hosts on sunflower was a single act that occurred once and all invasive races are descendants from ancient Caucasus population. Probably genes related to O. cumana aggressiveness should be identified and used for molecular markers to determine genetic relationships within and among O. cumana populations.N

Indigenous highly virulent accessions of the sunflower root parasitic weed Orobanche cumana

10 pages; 5 tables; 2 figuresOrobanche cumana (broomrape) is a severe constraint to sunflower production in southern and eastern Europe and the Middle East. Races A to E of this parasitic weed controlled by genes Or1 to Or5 have been described. A study of 38 seed accessions of O. cumana collected from different locations in Spain between 1983 and 2003 investigated the effect of long-term storage in the laboratory on germination and infectivity and assessed their virulence on a number of sunflower cultivars. Only 18 infected the susceptible cultivar B117. Infectivity was maintained for up to 17 years of storage, but with a greatly decreased vigour as compared with that of recently collected seed. The 12 oldest viable accessions overcame the resistance of the gene Or5 (in resistant line NR5). Seven out of them, in particular those collected in 1988 and 1989, were identified as race F. Three accessions were identified as race E allegedly holding components of higher virulence. Our results show evidence of the occurrence of race F prior to the use of sunflower hybrids resistant to race E, suggesting the former as indigenous to the country. This finding suggests the necessity of a continuous breeding of sunflower for resistance to O. cumana. The effectiveness and sustainability of genetic resistance must rely on the knowledge of the diverse virulence characteristics of O. cumana accessions.Ramón Areces Foundation (Madrid, Spain). Pioneer Hi-Bred SL (Sevilla, Spain), PR64A71Peer reviewe

Genetic diversity of wild Orobanche cernua L. populations from Southeastern Spain

Ponencia presentada en el 11th World Congress on PArasitic Plants, celebrado en Martina Franca (Italia) del 7 al 12 de junio de 2011.Peer Reviewe