Research
PhD
Since October 2012
Thesis: Usability of nuclear single-copy genes for phylogenetic analyses of grasslike families of the order Poales. Supervisor: Prof. Martin Röser
The mainly wind-pollinated order Poales comprises with around 20,000 taxa more than one third of the monocots and dominates many vegetation types worldwide. Grasses, sedges and their relatives originated probably towards the end of the Cretaceous period more than 65 million years ago in wet, nutrient-poor, sunny habitats of South America.
The order is divided into three basal families (Rapateaceae, Typhaceae and Bromeliaceae) and four major clades:
1. graminids (Poaceae, Ecdeiocoleaceae, Joinvilleaceae and Flagellariaceae)
2. restiids (Restionaceae, Centrolepidaceae and Anarthriaceae)
3. xyrids (Mayacaceae, Eriocaulaceae and Xyridaceae)
4. cyperids (Cyperaceae, Juncaceae and Thurniaceae).
Many of these groups are dominant in their representative habitats, for example, the grasses in savannas and steppes, the sedges in wet grasslands and the Bromeliaceae in parts of tropical South America. Current families of Polaes occur in nearly all non-marine areas, between the equator and the poles, from floating plants to desert plants and on most, if not all, soil types. The grasslike families are of vital economic and ecological significance.
Poaceae play the most important role for the daily sustenance of humans and animals. These are ensured mainly by cereal grasses (such as rice, wheat and corn), whose starchy fruits (caryopsis) provide a direct source of carbohydrate. Fresh fodder, hay, grains, silage and bran form the food base for animal production.
The grasses are one of the largest families of flowering plants consisting of approximately 10,000 species classified in 600–700 genera. Subfamilies Anomochlooideae, Pharoideae and Puelioideae form the early diverging lineages as sister to a monophyletic group, which split into the two major clades:
1. BEP clade (Bambusoideae, Ehrhartoideae and Pooideae)
2. PACMAD clade (Panicoideae, Arundinoideae, Chloridoideae, Micrairoideae, Aristidoideae and Danthonioideae).
Up to now questions of molecular evolution were limited by the enormous size of this lineage, so only few genera have been analysed and the focus is still on traditional morphologic studies. Intensively conducted molecular investigations on cultivated grasses (cf. rice and wheat genome) are based on interests of breeding progress in agriculture. In contrast, there is a much lower state of knowledge in wild grasses. These offer a genetic pool of vital importance (e.g. stress tolerance, pest- and disease-resistance) for applied lines of research (green genetic engineering, development assistance, sustained and biological agriculture). Molecular biological analyses are of key importance in research on grasslike families and wild grasses, their biological properties and investigations on phylogenetic differentiation processes (e.g. polyploidization, hybridization, introgression). The import of genetic resources from wild grasses and closely related taxa of Poales-families into the breeding efforts of modern elite varieties could contribute to food security of a steadily increasing world population.