Research Training Fellowship Program Bioeconomy Foci
Research focus: Monolignol biosynthesis genes in maize – molecular switches for bioethanol conversion of stover
Primary advisor: Dr. Thomas Lübberstedt Thomas.Lubberstedt@agrsci.dk
Description of the research opportunity: Digestibility of cell walls was recognized as major target for improving the feeding value of silage maize, and will likely be crucial for ethanol production from stems and leaves, which is depending on accessibility of celluloses and hemicelluloses in cell walls. Brown-midrib (bm) mutants show significantly reduced lignin content, altered lignin composition, and a significantly higher cell-wall digestibility. Of the four known bm loci, bm3 exhibits the strongest effect on the plant phenotype and codes for caffeic O-methyltransferase (COMT), a key enzyme involved in biosynthesis of lignin precursors (monolignols). Several feeding studies have proven the positive impact of bm3 on digestibility of forage maize. We studied the nucleotide diversity and linkage disequilibrium (LD) across 2.3 kb of the COMT locus in 42 inbred lines (Zein et al. 2007) and found associations between cell wall digestibility and genetic variation at the COMT locus, as well as for other “lignin genes” such as CCoAOMT-2. Thus, by association analysis, causative polymorphisms have been identified as prerequisite towards development of diagnostic “functional” markers. The goal of this project is to evaluate, whether OMT or other lignification genes are crucial for development of “high ethanol conversion” genotypes, and to understand the nature of allelic variation at these genes at the molecular level. Knowledge on the molecular causes behind the effect of these polymorphisms on digestibility and other traits will allow targeted development of optimal alleles for modulation of cell-wall structure, also in other grass species.
Description of the training opportunity: The project will involve scientists within the Agronomy Department and other departments working in the area of bio-energy. Training will be multidisciplinary in the areas of agronomy, plant breeding, genomics, bioinformatics, and plant physiology. An essential part of the training is the development of personal and scientific skills, the latter including presentation of results on conferences and publication in refereed journals. The project will be conducted at a newly established chair in close collaboration with European research institutions.
Desired skill set: : Student(s) involved in this projects should have a documented strong interest to work at the interface between plant breeding and plant genomics. Experience in either or both fields, as well as in bioinformatics are desirable.
Funding plan: Start-up money is available at the newly established chair to support funding. In addition, funding and collaboration opportunities will be sought with breeding and energy-related companies. If successful, the latter will provide excellent job opportunities after completion of the Ph.D.
Relevant citations:
Andersen, J.R., Lübberstedt, T. (2003) Functional markers in plants. Trends in Plant Sciences 8: 554-560
Andersen, J.R., Zein, I., Krützfeldt, B., Eder, J., Ouzunova, M., Wenzel, G., Lübberstedt, T. (2007) Polymorphisms at the Phenylalanine Ammonia-Lyase locus are associated with forage quality in European maize (Zea mays L.). Theor. Appl. Genet. 114: 307-319
Lübberstedt, T., Melchinger, A.E., Schön, C.C., Utz, H.F., Klein, D. (1997) QTL mapping in testcrosses of European flint lines of maize: I. Comparison of different testers for forage yield traits. Crop Sci. 37, 921-931
Lübberstedt, T., Melchinger, A.E., Klein, D., Degenhardt, H., Paul, C. (1997) QTL mapping in testcrosses of European flint lines of maize: II. Comparison of different testers for forage quality traits. Crop Sci. 37, 1913-1922
Lübberstedt, T., Melchinger, A.E., Fähr, S., Klein, D., Dally, A., Westhoff, P. (1998) QTL mapping in testcrosses of flint lines of maize: III. Comparison across populations for forage traits. Crop Sci. 38, 1278-1289
Lübberstedt, T. (2005) Objectives and benefits of molecular breeding in forage species. In: Molecular breeding for the genetic improvement of forage crops and turf, M.O.
Humphreys (ed.), Wageningen Academic Publishers, Wageningen, 19-30
Lübberstedt, T., Zein, I., Andersen, J.R., Wenzel, G., Krützfeldt, B., Eder, J., Ouzunova, M., Shi, C. (2005) Development and application of functional markers in maize. Euphytica 146:101-108
Lübberstedt, T. (2007) Application of genomics in forage crop breeding. In: Genomics assisted crop improvement: Vol. 2: Genomics applications in Crops, R.K. Varshney und R. Tuberosa (eds.), Springer, Heidelberg 281-305
Shi, C., Koch, G., Ouzunova, M., Wenzel, G., Zein, I., Lübberstedt, T. (2006) Comparison of maize brown-midrib isogenic lines by cellular UV-microspectrophotometry and comparative transcript profiling. Plant Mol. Biol. 62: 697-714
Shi, C., Uzarowska, A., Ouzunova, M., Wenzel, G., Lübberstedt, T. (2007) Association between cell wall digestibility and candidate gene expression profiles by application of genetical genomics to a Flint Flint maize recombinant inbred line population. BMC Genomics 8:22
Wollenweber, B., Porter, J., Lübberstedt, T. (2005) Need for multidisciplinary research towards a second green revolution. Curr. Opin. Plant Biol. 8: 1-5
Zein, I., Wenzel, G., Andersen, J.R., Lübberstedt, T. (2007) Low level of linkage disequilibrium at the COMT (Caffeic acid O-methyltransferase) locus in European maize (Zea mays L.). Gen Res & Crop Evol. 54: 139-148
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