NON-TECHNICAL SUMMARY: The primary problem we are studying is Fusarium head blight of wheat and barley. We are also incorporating useful genetic variation into cultivated barley; examining the control of tiller number in barley; and developing a system for barley genomics studies. My lab is primarily focused on utilizing molecular genetics to improve the efficiency and productivity of wheat and barley.

OBJECTIVES: There are five objectives for this project including: (1) develop transgenic wheat and barley with resistance to Fusarium head blight; (2) study the molecular interactions between wheat/barley and Fusarium graminearum; (3) use Hordeum vulgare subsp. spontaneum to identify useful genetic variation in barley; (4) study the genetics of tillering in barley; and (5) develop barley into a model system for genomics studies.

APPROACH: The general approaches we will take are to utilize molecular genetics, genomics and bioinformatics. We will develop transgenic wheat and barley plants with a variety of genes with the potential to provide resistance to Fusarium head blight (FHB). These lines will be tested in the greenhouse and field for resistance to FHB. We will use the barley and wheat Affymetrix GeneChip to examine gene expression patterns in barley and wheat infected with F. graminearum. We will also identify regions of the barley genome through genetic mapping and association genetics that contain disease resistance, and beneficial agronomic and domestication traits in wild barleys. Regions of the wild barley genome carrying beneficial traits will be incorporated into cultivated barley. We will isolate a gene that controls tiller number in barley and use the barley1 GeneChip to examine gene expression in a set of low tillering barley mutants. We will also use wheat-barley addition lines in combination with the barley1 GeneChip to study barley gene expression in a wheat genetic background and to conduct high throughput genetic mapping of the barley genome.

KEYWORDS: barley; wheat; fusarium graminearum; tillering; bioinformatics; molecular genetics; head blight; fusarium; fungus diseases (plants); molecular biology; plant improvement; transgenic plants; wild plants; genomes; plant genetics; plant disease resistance; crop varieties; genetic variance; quantitative genetics; gene loci; traits; bacteria; artificial chromosomes; genetic mapping

PROGRESS: 2006/01 TO 2006/12
Projects conducted included: (1) investigating the interaction between small grains (wheat and barley) and Fusarium graminearum during infection; (2) developing and characterizing transgenic wheat carrying antifungal protein genes; (3) studying the molecular genetics of axillary meristem development and tillering in barley; (4) examining the usefulness of wild barleys in barley improvement; (5) developing F. graminearum genomics resources; and (6) developing barley genomics resources. We developed a genomics approach to characterize QTL for FHB resistance and to investigate the interactions between small grains and F. graminearum during infection. We used Affymetrix GeneChips for barley and wheat to examine gene expression profiles in pairs of near-isogenic lines (NILs) in barley and wheat for FHB resistance QTL. In addition, we examined gene expression in the susceptible barley cultivar Morex during F. graminearum infection with a trichothecene producing and non-producing strains of the fungus. The analysis are ongoing and we are beginning to conduct a meta analysis of these experiments. We developed transgenic wheat lines that exhibited reduced FHB severity in the greenhouse and field. We used the Barley1 GeneChip to identify genes that are up and down regulated in four low-tillering barley mutants compared to wildtype and the analysis is ongoing. We integrated the map position of three low tillering barley mutants to the molecular genetic map. We mapped QTL controlling morphological traits that differentiate wild from cultivated barley. We identified 421 F. graminearum genes that are specifically expressed during barley infection. We physically mapped 1,258 genes to barley chromosome arms. Finally, we are participating in the development of a 3,000 marker single nucleotide polymorphism (SNP) map of barley.

IMPACT: 2006/01 TO 2006/12
We are identifying the molecular interactions between the small grains wheat and barley and Fusarium graminearum. We are also developing the molecular genetic tools for enhancing FHB resistance in wheat and barley. In addition, we are describing the regulatory pathways controlling axillary meristem development and tillering in barley. Furthermore, we identified QTL controlling morphological traits in barley. We identified F. graminearum genes that are specifically expressed during barley infection. Moreover, we physically mapped 1,258 genes on the barley genome. Participated in the development of a barley SNP map.

PUBLICATIONS (not previously reported): 2006/01 TO 2006/12
1. Mammadov, J.A., Liu, Z., Biyashev, R.M., Muehlbauer, G.J. and Saghai Maroof, M.A. 2006. Cloning, genetic and physical mapping of resistance gene analogs in barley (Hordeum vulgare). Plant Breeding 125:32-42.
2. Mackintosh, C.A., Garvin, D.F., Radmer, L.E., Heinen, S.J. and Muehlbauer, G.J. 2006. A model wheat cultivar for transformation to improve resistance to Fusarium Head Blight. Plant Cell Reports 25:313-319.
3. Boddu, J., Cho, S., Kruger, W.M. and Muehlbauer, G.J. 2006. Transcriptome analysis of the barley-Fusarium graminearum interaction. Mol. Plant-Microbe Interact. 19:407-417.
4. Yun, S.J., Gyenis, L., Bossolini, E., Hayes, P.M., Matus, I., Smith, K.P., Steffenson, B.J., Tuberosa R. and Muehlbauer, G.J. 2006. Validation of quantitative trait loci for multiple disease resistances using advanced backcross lines developed with a wild barley (Hordeum vulgare subsp. spontaneum). Crop Sci. 46:1179-1186.
5. Cho, S., Garvin, D.F. and Muehlbauer, G.J. 2006. Transcriptome analysis and physical mapping of barley genes in wheat-barley chromosome addition lines. Genetics 172:1277-1285.
6. Muehlbauer, G.J., Bhau, B.S., Syed, N.H., Heinen, S., Cho, S., Marshall, D., Pateyron, S., Buisine, N., Chalhoub, B. and Flavell, A.J. 2006. A hAT superfamily transposase domesticated by the cereal grass genome. Mol Gen Genomics 275:553-563.
7. Guldener, U., Seong, K., Boddu, J., Cho, S., Trail, F., Xu, J-R., Adam, G., Mewes, H-W., Muehlbauer, G.J. and Kistler, H.C. 2006. Development of a Fusarium graminearum Affymetrix GeneChip for profiling fungal gene expression in vitro and in planta. Fungal Genetics and Biology 43:316-325.
8. Druka, A., Muehlbauer, G.J., Druka, I., Caldo, R., Baumann, U., Schreiber, A., Rostoks, N., Wise, R., Close, T., Kleinhofs, A., Graner, A. Schulman, A., Langridge, P., Sato, K., Hayes, P., McNicol, J., Marshall, D. and Waugh, R. 2006. An atlas of gene expression from seed to seed through barley development. Funct. Integr. Genet. 6:202-211.
9. Wenzl, P., Li, H., Carling, J., Zhou, M., Raman, H., Paul, E., Hearnden, P., Maier, C., Xia, L., Caig, V., Ovesna, J., Cakir, M., Poulsen, D., Wang, J., Raman, R., Smith, K.P., Muehlbauer, G.J., Chalmers, K.J., Kleinhofs, A., Huttner, E and Kilian, A. 2006. A high-density consensus map of barley linking DArT markers to SSR, RFLP and STS loci and phenotypic traits. BMC Genomics 7:206.
10. Mackintosh, C.A., Lewis, J., Radmer, L.E., Shin, S., Heinen, S.J., Smith, L.A., Wyckoff, M.N., Dill-Macky, R., Evans, C.K., Kravchenko, S., Baldridge, G.D., Zeyen, R.J. and G.J. Muehlbauer, G.J. 2006. Overexpression of defense response genes enhances the resistance of wheat to Fusarium Head Blight. Plant Cell Reports (in press)

PROJECT CONTACT:
Name: Muehlbauer, G. J.
Phone: 612-625-6228
Fax: 612-625-1268
Email: muehl003@umn.edu