The project aims to control the Fusarium Head blight (FEB) or scab disease (Fusarium graminearum and F. culmorum) of wheat and to decrease toxins of Fusarium preventively while using the genetic resistance to this pathogen. This project has for goal to characterize the genetic components of this resistance. The scab disease of the ear is currently a problem of food security of the Walloon, Belgian and European agriculture. Damages caused by the different types of Fusarium are since several years in increase and seen the importance of problems bound to the presence of mycotoxins (trichothecenes: deoxynivalenol-DON, nivalenol-NIV) causing human diseases. Watch networks have been established. Different types of struggle exist against the Fusarium Head blight; the genetic resistance is one of the more efficient and economic means to fight against this pest. However, known sources of resistance were present in the unadapted germplasms in our regions. The creation and the release of resistant Walloon varieties (Centenaire and Fourmi) recently on the market permit to consider their generalized application in molecular markers assisted plant selection.
Objectives
Our project is aiming at localization of loci implied in the adult resistance to the wheat scab disease. Links between molecular markers and the quantitative loci (QTL) implied in the resistance to the Fusarium Head blight have to be found. The development of detailed genetic maps and the utilization of the most recent molecular markers (microsatellites, RFLP, AFLP, EST, SNP) as well as the statistical tools permit the localization of loci involved in the quantitative characters (QTL). We will study and locate on chromosomal maps putative gene candidates (ABC carriers…) involved in the various mechanisms of plant defence. It will permit to analyze the genetic determinism of the complex quantitative characters of the adult resistance and to determine the genetic origin of this European resistance. The discovery of molecular markers bound to these genes will permit to follow their introgression during the creation of new varieties and so, to shorten the necessary time to produce a commercial resistant variety to this disease.
Expected results
We will use different molecular markers: microsatellites, EST, AFLP and RFLP. These markers will be analyzed on parents of populations and those revealing a a polymorphism will be analyzed on the different members of populations. Genetic maps will be raised with the software Mapmaker and the QTL will be investigated. Segregation data of the molecular markers and of the quantitative characters evaluated will be treated according to different methods. The softwares Mapmaker QTL and QTL cartographers will be used as well as the classic tests (ANOVA, regression). The map of the chromosomal zones implied in the considered characters will be refined in order to better define the localization of the QTL put in evidence. Specific probes for gene candidates involved in mechanisms of resistance will be produced by PCR and will be also positioned on the maps One can analyze the program of research in the different steps: 1. Creation and fixation of different populations implying parents resistant to the scab disease 2. Genetic analyses of these populations with different molecular markers 3. Research of genes candidates involved in the resistance to the scab disease 4. Establishment of genetic maps regrouping the different markers 5. Assessment of the quantitative characters of resistance to the scab disease 6. Research of QTL and links between the molecular markers and genes involved in the resistance 7. Development of new plant material and molecular markers assisted selection
Results obtained
1. Creation and fixing of populations Two varieties, Centenaire and Fourmi, selected respectively by Jorion et Fils and by the CRA-W, present a resistance to the Fusarium Head blight in conditions of fields infection. From these 2 varieties, crossings have been done implying a sensitive and a resistant parent in order to permit a genetic analysis of the resistance components. We have at our disposal F3 populations produced by Jorion et Fils: S266 (Centenaire X Ordeal), S 269 (Centenaire X UNBR 39) as well as of F2 populations: T257 (Centenaire X Agami). We also possess populations established by the CRA-W: 28.0.1 (Inuit X 63.04.5), 27.0.1 (Jade X Fourmi) and 25.0.1 (Inuit X Centenaire). 2. Observations of the resistance and material selection. During the year 2004, the hereover described populations have been planted in parcels in the fields (Jorion et fils in Frasnes-lez-Buissenal and CRA-W in Gembloux). Phytopathological observations have been done during the year 2004 at various stages of the plant growth, the Fusarium Head blight was diagnosed and the resistance of plants repeatedly evaluated by a global quotation. On the other hand, a genetically representative sample consisting of 250 plants, picked up at random, was constituted within each populations. These plants will be sowed (6-10 grains coming from one ear) in lines in test field parcels in order to continue the phytopathological assessment of plant samples, by evaluation of the Fusarium resistance, on basis of the global value of the resistance. This material will also permit us to proceed to the populations fixation and to raise the genetic maps of populations. Finally, we have isolated from the populations S266 (F3) and 28.0.1 (F2), 25 resistant plants and 25 sensitive plants. This material will be used in the so-called in mixture or BSA (Bulk Segregeant Analysis) molecular analyses, permitting to determine the molecular markers bound to resistance genes.
Partners
This work is realized in collaboration with Ducourouble M. (V. Jorion et Fils) and Dekeyser A., Chandelier A., Detrixhe P. (CRA-W).
