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New ways to improve genetic resistance against sunflower broomrape

For many decades, sunflower broomrape has been damaging crops in Europe. It appeared in 2009 in France since when more regions have become infested. As members of a project funded by Promosol, INRA scientists in Toulouse and their partners are exploring the interactions between sunflower and broomrape in order to improve management of the risk induced by this parasitic weed.

Uninfected (3 on the left) and infected (3 on the right) sunflower plants susceptible to broomrape.The plants were grown in a S2 confinement glasshouse. The broomrape seeds were harvested on 9 September 2015 in an infected field in Bourret (Tarn et Garonne, France). © INRA
Updated on 09/14/2016
Published on 06/23/2016

Sunflower broomrape (Orobanche cumana), a parasitic weed

Sunflower (Helianthus annuus L.) is cultivated for its seeds that are used for human foods, livestock feeds and lipid chemistry.  In both Europe and Asia, this crop has become a victim of infestation by broomrape (Orobanche cumana), a parasitic plant that can cause yield losses of up to 80%. Spreading rapidly, its seeds can survive in the soil for more than ten years. To control this infestation, the selection of resistant sunflower varieties appears to be the most efficient and sustainable option.

Evaluation of the resistance of sunflower lines during the broomrape life cycle

The life cycle of broomrape counts four main stages, the first three occurring underground: (1) germination, (2) fixation-penetration of the parasite in the roots of the host (formation  of the haustorium), (3) formation of the tubercle, and (4) emergence of the stem, ending with flowering and seed production. 101 consanguinous and recombinant lines of sunflower from the French collection of genetic resources maintained by INRA in Toulouse have been tested for their resistance to several sources of O. cumana during stages (2), (3) and (4). The experiments were carried out  in a rhizotron system, in containers and in the field in Cordoba (Spain) by artificial inoculation.  Resistance to broomrape was evaluated by phenotyping at stages (2) to (4) of the parasite's development.  All the lines were also genotyped at INRA's Gentyane platform (see insert) using a high-throughput genotyping array developed in the context of the SUNRISE project (see: For more information).

Analysis of the genetic control of resistance in the H. annuus / O. cumana pathosystem

The expression of resistance is complex.  Major resistance genes were mapped but overall resistance, already introduced in certain hybrids, has since been circumvented by the parasite in some European regions.  In order to ensure the sustainability of resistance, the scientists mapped quantitative resistant trait loci (QTLs) that could block the parasite at different stages in its life cycle.  The strategy of coupling major resistance genes with quantitative resistance is able to prevent the risk of circumvention.
Phenotyping revealed three profiles for the lines: resistant, susceptible and partially resistant.  By combining these data with those from the genotyping of sunflower (21,200 polymorphous markers), 17 QTLs controlling resistance to the different life cycle stages of broomrape were mapped.  Two QTLs seemed promising: one controls the early stage of interaction, while the other concerns the number of above-ground broomrape shoots during the final stage.  The attachment of parasitic radicles to the sunflower root is an important mechanism in establishing the interaction and allows the parasite to grow.  Browning was observed at the attachment point on the host root in some sunflower lines endowed with a mechanism that rapidly rendered the interaction incompatible. Similarly, at the tubercle formation stage, the degree of resistance could be seen from the contrast between the presence of healthy tubercles (yellow) and those that were necrotic (brown).

Opportunities for new breeding programmes

To better characterise the interaction between the host plant and its parasite, and to develop sustainable resistance, new routine phenotyping tools will be necessary.  Field experiments need to be pursued in order to analyse the environmental factors involved: soil composition, the effect of rainfall on the expression of symptoms, or the contribution of weeds and soil microflora.  It will thus be possible to obtain a broader view of the dynamics of this astonishing interaction. As for the QTLs that control the number of above-ground broomrape shoots, these could rapidly be used in future breeding programmes.

reference

  • Louarn J., Boniface M.-C., Pouilly N., Velasco L., Pérez-Vich B., Vincourt P., Muños S., Sunflower Resistance to Broomrape (Orobanche cumana) Is Controlled by Specific QTLs for Different Parasitism Stages, Frontiers in Plant Science, 2016 May 10;7:590. DOI: 10.3389/fpls.2016.00590. eCollection 2016.

Find out more

The following partners are involved in this research programme:

  • Promosol (funder of the project): an association grouping the UFS (French Seed Companies Association), Terres Univia (the interprofessional body for plant oils and proteins), Terres Inovia and INRA.
  • Université de Nantes (Plant Pathology Laboratory)
  • CSIC Cordoba (Consejo Superior de Investigaciones Cientificas  - Instituto de Agricultura Sostenible) Spain.

more about

High throughput genotyping and sequencing platform: GENTYANE

platform genotyping and sequencing

http://gentyane.clermont.inra.fr/

Gentyane is a genotyping and sequencing platform accredited by IBISA (Infrastructures for Biology, Health and Agronomy) and belongs to a network of platforms set up by INRA's Plant Biology and Breeding Division (BAP). Attached to the INRA Centre for Auvergne Rhône-Alpes in Clermont-Ferrand, it forms part of the INRA-Université Blaise Pascal (UBP) Joint Research Unit for the Genetics, Diversity and Ecophysiology of Cereals (UMR GDEC, 1095). Initiation of the platform benefited from funding from the INRA Scientific Division for Plants and Plant Products (DSPPV), the Auvergne-Rhône Alpes Regional Council, the IBISA Scientific Interest Group) and the European FEDER fund.

Scientific objectives of the platform:

  1. To support research carried out by different teams in UMR GDEC;
  2. To provide genotyping and sequencing services for other INRA teams or other public and private organisations;
  3. To ensure technology watch that will enable the installation of new tools that can respond better, more rapidly and at lower cost to the needs of users.

Services proposed: DNA extraction, Genotyping (Microsatellite, SNP Kaspar, SNP Axiom), Sequencing (Illumina MiSeq).

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PROMOSOL is an association that promotes the breeding of oilseed plants.  Its members include Terres UNIVIA (the interprofessional body for plant oils and proteins), Terres INOVIA (the technical institute for the producers of oilseed, protein and hemp crops and their different sectors), INRA (National Institute for Agricultural Research) and the UFS (French Seed Companies Association).  

The aim of PROMOSOL is to support the development of knowledge on the breeding of oilseed plants and encourage actions that will foster the dissemination of scientific advances.  To achieve this objective, the association draws on the quality of its network in terms of both the number of actors involved and the expertise of its members.

For 39 years, PROMOSOL has offered a model of collaboration between public and private research, the overall objective being to increase knowledge on the breeding of rapeseed and sunflower thanks to the implementation of numerous research programmes.

Contact: laetitia.authenac@ufs-asso.com
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Sunrise 

logo SUNRISE. © INRA
© INRA

Sunrise is an Investment for the Future (PIA) project funded for eight years (2012-2020) by the ANR and accredited by the Scientific Interest Group on Green Biotechnologies and the Agri-Sud-Ouest-Innovation competitiveness cluster.
Budget: €21.6 million, €7 million of which has come from the ANR.

Sunrise has three main objectives:

  • To improve the production of sunflower oil under conditions adapted to climate change and respectful of the environment.
  • To understand the genetic and molecular bases that control plant physiology and development in order to predict the characteristics of hybrids.
  • To develop for the entire sector the tools and methods that will improve control of the crop.

The SUNRISE project is being coordinated by the Joint Research Unit for Plant-Micro-organism Interactions (UMR LIPM, INRA Toulouse) and groups 16 public and private partners:

  • 9 public research units attached to INRA, Université Pierre et Marie Curie, Université Paris Sud, CNRS, Université Toulouse I and  Université de Bordeaux;
  • 6 seed companies: Biogemma, Caussade, Maïsadour, RAGT 2n, Soltis, Syngenta
  • 1 technical institute: Terres Inovia

www.sunrise-project.fr/en/