Quantitative Crop Genetics

Research topics of the Quantitative Crop Genetics Group

    1. Quantitative genetics:

Most traits that are important for fitness and agricultural value of plants are quantitative traits. Such traits are affected by many genes, the environment, and interactions between genes and the environment. The basic questions of quantitative genetics are:

• Is phenotypic variance due to genetics or environment?
• What are the forces that maintain variation within populations?
• What is the relative importance of existing variation vs. new mutations?
• Is genotypic variation caused by a few loci of large effects or many loci with small effects?
• How do alleles at different loci interact?

We are developing new genetic materials for barley and rapeseed as well as biometrical methods to find answers to these questions.

2. Iron homeostasis in graminaceous monocots

Iron (Fe) is involved in many essential metabolic processes of plants such as hormon synthesis, DNA synthesis, chlorophyll biosynthesis, and various other fundamental redox reactions. Therefore, insufficient Fe uptake of plants leads to chlorosis but also significant reductions in yield. Worldwide, this problem occurs on about one third of the arable land, illustrating both, the importance but also the potential of improving the Fe supply of plants.

Fe is the fourth most abundant element in the earth crust. However, under aerobic conditions it exists mainly in forms of oxyhydrates with a low solubility and consequently low plant availability. Therefore, the main problem with which plants have to cope is not the Fe abundance but its solubility.

Throughout the evolution process, plants evolved two distinct adaptation mechanisms for Fe acquisition. Strategy I plants encompass dicots and nongraminaceous monocots that mainly respond to Fe limited growth conditions with three major processes that take place at the root plasma membrane: (a) activation of the plasma membrane H+-ATPase, (b) an enhanced reduction capacity of Fe(III), and (c) increased uptake capacity for Fe2+. Graminaceous monocots, such as wheat, barley, and maize are strategy II plants. In response to Fe deficiency, strategy II plants produce chelating substances, so called phytosiderophores and secret them into the rhizosphere. Phytosiderophores are hexadentate ligands that coordinate Fe(III) with their amino and carboxyl groups. In the plasma membrane of root cells, a specific transport system which is activated under Fe limiting conditions, exists for ferrated phytosiderophore-complexes. Studies with double-labeled-Fe-phytosiderophore complexes revealed that Fe(III)-phytosiderophores are mainly taken up as undissociated Fe chelate molecules in apical root zones.

Fe is not only involved in many important metabolic processes of plants but is also an essential micronutrient for human beings. Worldwide, as many as 3 billion people are affected by Fe deficiency. It has negative impacts on human health and well-being, such as decreasing work capacity and slowing the cognition development of iron-deficient children. For developing countries, Fe deficiency causes long-term costs of about 2 - 8 % of their respective gross national product. Therefore, the improvement of the Fe supply of human populations is respected as one of the major tasks.

Africa, Latin America, and the developing countries in Asia are the regions in the world in which the proportion of the population affected by Fe deficiency is very high. In those regions, the consumption of cereals covers between 35 and 60 % of the daily calories. Therefore, the increase of the Fe concentration in the kernels of cereals has the potential to dramatically improve the Fe supply of the human population. However, the first step is to improve the understanding of the Fe uptake and translocation in plants. We are applying genetic, quantitative genetic, and genomic approaches to understand the iron homeostasis of graminaceous monocots on the molecular level.

The successful work on the above mentioned topics requires the collaborative efforts of skilled researchers from many different fields.

As a productive group, we are always interested in attracting talented scientists. Candidates with an excellent training background in Genomics, Molecular Biology, Plant Breeding, Quantitative Genetics, or Statistical Genetics are encouraged to contact us at stich[a]mpipz.mpg.de to discuss the possibilites for joining the group as visitor, PhD student, or Postdoc.