Influence of nitrogen on root morphology
Nitrogen (N) is the quantitatively most important nutrient in cropping systems. However, a considerable N fraction is lost through runoffs with detrimental consequences for the environment and human health. Increasing the plant N uptake by optimizing the degree of root branching for exploring a larger soil volume in search of the mobile nitrate resource may contribute to limit soil leaching. Arabidopsis model species and rapeseed parented crop are studied. Our aim is to understand the genetic control of root morphology and how it is impacted by N nutrition. We are identify genomic regions associated to root morphological traits by performing association mapping with large diversity panels and linkage mapping with experimental populations issued from biparental crosses. That information is complemented with root transcriptome sequencing data which will allow detecting gene copies differentially expressed between accessions and between N nutrition conditions.
Natural variation of the ionome
The ionome is the mineral nutrient and trace element composition of an organism. Ionomics is a high-throughput elemental profiling approach to study the molecular mechanistic basis underlying the ionome (Molecular Plant 9 : 787-797). The model plant species Arabidopsis thaliana has a broad geographical distribution and offers a great opportunity to unravel variation in adaptive evolutionary responses to the environment. This research focuses on naturally occurring genetic variability of the ionome.
The plant material is a unique collection of 210 Arabidopsis accessions, which we have collected in Belgium and the Netherlands. A special emphasis was put on the urban environment of Brussels city (Belgium) and the Texel island (the Netherlands). During a ‘common garden’ experiment carried on agar plates, we have measured the elemental profiles and root morphological traits. Our goal is to establish and understand correlations between the soil physico-chemical characteristics of harvesting sites and phenotypic traits measured under controlled laboratory conditions. A genome wide association study is conducted to identify genes and alleles that regulate phenotypic traits. This fundamental knowledge gained in the model species Arabidopsis could help defining strategies to optimize root morphology and to improve the nutritional value, through the marker assisted selection of cultivated plants with more complex genomes (e.g., rapeseed).
Cesium toxicity
Cesium is a rare chemical element that has physical and chemical properties like that of potassium. That element is not essential for plant growth. Cesium has only one stable isotope (133Cs) and several radioisotopes (e.g., 137Cs). In 2011, the accident at the Fukushima Daiichi nuclear power plant released radioactive nuclides in agricultural areas of Japan. Therefore, there is an urgent need to elucidate the absorption and transport mechanisms of cesium in plants, to develop strategies for reducing environmental pollution and contamination of agricultural products.
The research aims at characterizing, under laboratory conditions, the impact of cesium toxicity on the physiology of the model plant Arabidopsis and of the poplar tree. The first objective is to intoxicate plants with cesium and to perform a global transcriptome sequencing to compare gene expression in roots and leaves. The second objective is to characterize a few candidate genes to demonstrate the involvement of these in the absorption and transport of cesium.