Toward solving the mysteries of quantitative resistance of wheat to Fusarium graminearum, the causal agent of head blight

Beschreibung

Resistance is a new hope to effectively control Fusarium head blight (FHB), one of the major constraints to the quality of wheat products. Since minute amounts of the fungal toxin deoxynivalenol (DON) and its derivatives nivalenol (NIV) and zearalenone (ZON) render wheat grains and flour poisonous to humans and animals, breeders are aiming at increasing the cereal´s resistance to this by conventional means difficult-to-control disease. The natural base of quantitative resistance introgressed from the Japanese resource Sumai 3 is not known and the inheritance of reduced susceptibility is complex, as has been revealed by crossing and genetic mapping of QTLs. Within a project funded by the Austrian genome program (GENAU) we are applying genomics approaches to elucidate mechanisms, key genes and their timed response during the interaction of wheat with elicitors of Fusarium graminearum. The resistant line CM carrying genes of Sumai 3 was crossed to the susceptible variety Remus and FHB resistant and susceptible progenies were selected. A single, highly resistant progeny line, E2, was then used for the generation of embryonic callus and cell suspensions. A suppressive subtractive cDNA library was generated from mRNA of callus following challenge by F. graminearum culture filtrate. Of the library´s 1200 single clones of low redundancy, 182 resulted overexpressed in response to the challenge treatment, and the expression level of 43 was reduced compared to their expression within water-treated control calli. Quantitative real time PCR was applied to confirm differential expression levels of several genes. All differentially expressed genes (clones) were sequenced. Database searches for similarity with known plant genes and for presence of similar sequences in specific cDNA and EST libraries revealed that the major part of our genes are highly similar or identical to entries within the TIGR wheat gene database. Most (x%) genes may encode proteins involved in protein synthesis, such as elongation factors and ribosomal proteins. Other prominent fractions of genes have been characterized in processes of plant defense (resistance and stress tolerance). About 15% of the genes and their respective proteins have, at present, no known function. One hundred and fifty of the differentially expressed genes were selected for further use in microarray-based studies of timed response of several resistant and susceptible wheat lines to challenge by single mycotoxins and fungal strains varying for aggressiveness.

Zeitraum	11 Juli 2004 → 16 Juli 2004
Ereignistitel	3. Plant Genomics European Meetings (GEMS), Sept. 22-25, 2004, Lyon, France, P162, p. 252.
Veranstaltungstyp	Sonstiges
Bekanntheitsgrad	International