Abiotic stress tolerance and resource efficiency
The aim of our research is to contribute to the development of new varieties with improved adaptation to stressful environments. We approach this goal through basic research on the genetic and physiological basis of stress adaptation. In collaboration with institutions in the developing world we subsequently transfer our research findings to crop breeding and other applied sciences.
Focus
At present we focus mainly on work with rice as this is the most important food crop worldwide. It is also the crop with the best genetic/genomic resources available and can therefore serve as a model crop for other cereals such as barley, wheat or sorghum. At present we focus on abiotic stresses that limit crop yields in many parts of the world, investigating genetic and physiological causes of:
- tolerance to phosphorus deficiency and iron toxicity
- tolerance to drought and salinity
- enhanced root development under stress
In addition, we collaborate with partners on developing rice with improved nutritional quality, namely with increased zinc (Zn) concentrations in the rice grain. Such Zn biofortified rice is being developed and tested in Madagascar where Zn malnutrition is a national concern.
With the move to the University of Bonn we started work on resource capture and root development in maize in collaboration with the group of Peng Yu (INRES - Root Functional Biology).
Approach
We target natural genetic variation for abiotic stress tolerance within rice germplasm in order to identify novel tolerance alleles present within gene banks, association panels or QTL mapping populations. After mapping of loci associated with tolerance, candidate genes are identified and characterized and tolerance mechanisms are investigated physiologically. At various stages findings are confirmed by field experiments to assure results have practical relevance. A successful project would conclude with the development of molecular markers and their application in the marker assisted introgression of tolerance alleles into modern varieties with high yield potential but poor adaptation to target stresses.
Projects
Tolerance to phosphorus deficiency and iron toxicity
P deficiency: Research focuses on genotypic differences in tolerance to P deficiency, targeting mechanisms/genes that enhance internal P utilization efficiency (PUE) or P uptake from low-P soils (sites are located in Japan, South-East Asia, and Madagascar). Within P uptake we differentiate between root growth/architecture and P acquisition efficiency (PAE). We further investigate whether P loading into the grain can be reduced to improve P balances through lower P removal from fields at harvest. Work focuses on rice and in Madagascar has had a very applied variety selection and release component.
Fe toxicity: Together with collaborators at AfricaRice and LRI (Madagascar), QTLs associated with tolerance are being mapped and fine mapped. We further try to understand interactions between genotype and site-specific effects that affect the severity of Fe toxicity on one hand and efficacy of tolerance mechanisms on the other. Molecular studies are geared towards identification of candidate genes controlling such tolerance mechanisms.
Improved root development under stress
Whether we are concerned with the uptake of deficient or toxic nutrients, root properties are likely a key factor for observed genotypic differences. We are therefore focusing on root architectural properties and on the interaction of rice roots with their rhizosphere. Both aspects are investigated through modeling, experimental and genetic approaches. Allocation of resources (assimilates or limiting nutrients such as P) between shoot and root is a further topic of interest as we observed a more rapid re-allocation of resources for root growth in varieties adapted to low soil fertility.
Tolerance to drought and salt stress
A relatively new project that tries to exploit synergisms from the above projects. Donors with improved root development bring these traits into breeding populations that we test under water deficit or salt stress in the field in Madagascar. We focus primarily on rapid root development and the suitability of breeding lines for direct sowing in wet rice cultivation.
Rice with increased zinc content in the grain
Zinc (Zn) malnutrition is a global problem causing infant mortality, delaying infant development and reducing immune system function. Developing crops with higher Zn concentrations in edible parts, a process termed Zn biofortification, is seen as one of the most efficient ways to alleviate Zn malnutrition, especially for rural populations. With partners in Madagascar (FOFIFA, CIRAD) we test high-Zn breeding lines developed by HarvestPlus breeding programs elsewhere, and search for new high-Zn donor to initiate a local breeding program.